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Deep Learning Technology: Sebastian Arnold, Betty van Aken, Paul Grundmann, Felix A. Gers and Alexander Löser. Learning Contextualized Document Representations for Healthcare Answer Retrieval. The Web Conference 2020 (WWW'20)
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Despite extensive research, no agent has been approved for prevention and/or therapy of rhinovirus-induced diseases so far. Ruprintrivir selectively inhibits HRV 3C protease and shows potent, broad-spectrum anti-HRV activity in vitro . Ruprintrivir nasal spray (2% solution) prophylaxis reduced the proportion of subjects with positive viral culture by 26% and reduce viral titers, but did not decrease the frequency of colds. HRV RNA synthesis during replication can be blocked by deoxyribozymes, morpholino oligomers, and small interfering ribonucleic acids. The novel antiviral therapies that have been discovered recently, may one day add significantly to the armamentarium of antiviral agents, against respiratory viral infections in asthmatic children.
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Maternally-derived RSV neutralizing antibodies help to protect infants against RSV hospitalization. Palivizumab, a humanised monoclonal antibody against the RSV fusion protein is effective against RSV and wheezing in children and reduces hospitalization in high-risk individuals. RSV prophylaxis with palivizumab significantly reduced the relative risk of subsequent recurrent wheezing in nonatopic premature infants. Motavizumab is another monoclonal antibody against RSV, with an approximately 20-fold increase in ability to neutralize RSV and 100 fold increase in ability to reduce viral titers compared to palivizumab. Motavizumab was also found to be superior to palivizumab in reducing outpatient medically attended lower respiratory illness by 50%.
Infectious causes of respiratory disease are common in dogs; canine distemper virus, adenovirus 2, parainfluenza, influenza, herpesvirus, pneumovirus, respiratory coronavirus, Bordetella bronchiseptica, various Mycoplasma spp., and Streptococcus equi var. zooepidemicus are documented causes.1 Molecular diagnostic assays to detect viral and bacterial pathogens are available for these agents. In the United States, modified live vaccines (MLVx) for intranasal (IN) administration are currently available for adenovirus 2, B. bronchiseptica, and parainfluenza. These vaccines do not induce sterilizing immunity, and vaccinated dogs can still develop clinical signs of disease if exposed to virulent strains of the organisms.2 It is currently unknown if IN administration of MLVx against these agents results in positive molecular diagnostic assay results in dogs without previous vaccination. If transient positive molecular diagnostic assay results are common after vaccination, the positive predictive value of the diagnostic assays to predict disease caused by these agents in dogs would be decreased.
The purpose of this study was to determine the impact of administration of a single IN dose of a commercially available MLVx adenovirus 2, B. bronchiseptica, and parainfluenza containing vaccine,1 included as part of a facility standard initial vaccination series with a parenteral administration of MLVx containing adenovirus 2, canine distemper virus, and parvovirus, on the results of a commercially available polymerase chain reaction (PCR) panel that amplifies the RNA or DNA of the agents.2
The study was completed with Institutional Animal Care and Use approval. Beagle puppies housed at a commercial breeding facility were used.3 The puppies were housed in a closed facility without contact with other dogs and staff members followed facility barrier precautions over the course of the study. A sterile cotton swab was gently rubbed at the entrance to the external nares, and a second swab gently rubbed against the mucosa of the oropharynx in nonsedated puppies. The swabs were stored separately at 4°C in sterile plastic tubes and stored until shipped by overnight express on cold packs for performance of the molecular assays.2
A total of 12 puppies were screened twice as described, 1 week apart, and all were negative for nucleic acids of the target organisms. Eight puppies were randomly selected for the study and housed in a separate room at the breeding facility for the duration of the study. The puppies were approximately 9 weeks of age when samples were collected on Day 0 before the SQ administration of a MLVx containing adenovirus 2, canine distemper virus, and parvovirus4 and the IN administration of a MLVx1 containing adenovirus 2, B. bronchiseptica, and parainfluenza following manufacturer's instructions (approximately ½ mL per nares). Nasal and pharyngeal swabs were then collected on days 1, 2, 3, 4, 5, 6, 7, 10, 14, 17, 21, 24, and 28 for molecular analysis.2
Sneezing or coughing which have been associated with IN MLVx administration was not noted over the course of the study. Adverse effects associated with the collection of the nasal and oropharyngeal swabs were not noted. At the time the study was performed, the PCR panel utilized also included primers for canine distemper virus RNA; and none of the samples collected over the course of the study were positive. In contrast, nucleic acids of adenovirus 2, B. bronchiseptica, and parainfluenza were amplified from both sampling sites, from all 8 puppies, on multiple days after vaccine administration (Table 1). Because adenovirus 2 was administered in both vaccine types, source of that virus cannot be determined. Increasing numbers of positive samples after vaccination suggest local replication of the vaccinal strains. Decreasing numbers of positive samples over time suggest immune responses inhibiting organism replication. However, quantitative PCR assays normalized to total DNA/RNA on the swab would be needed to confirm or deny these hypotheses. The PCR laboratory adheres to standard operating procedures including use of positive and negative controls thus erroneous results are unlikely.
Agents considered most common for kennel cough syndrome include canine distemper virus, adenovirus 2, parainfluenza, and B. bronchiseptica. However, emerging pathogens include influenza, herpesvirus, respiratory coronavirus, pantropic coronavirus, pneumovirus, and others.1 All of these agents, as well as S. equi var. zooepidemicus and Mycoplasma spp., have been identified as causes of canine infectious respiratory disease. Determination of the agent is important for targeting treatment, particularly for dogs who fail to respond to standard treatment recommendations.2 In animal shelter environments, agent identification is critical for outbreak control and individual case management.3
Bacterial and viral shedding postvaccine administration complicates diagnostic testing and treatment. This is especially problematic in shelter environments as dogs are routinely vaccinated on intake. Viral shedding after vaccination has been detected in cats,4 people,5 cattle,6 pigs,7 and dogs.8 A vaccine strain of B. bronchiseptica was detected via nasal culture up to 4 weeks after IN vaccination of 2–week‐old puppies.9
Commercially available respiratory PCR panels are a relatively cost and time effective diagnostic method for identifying multiple respiratory pathogens. However, amplification of nucleic acids may inherently lead to inaccurate clinical diagnosis because small amounts can be amplified from some animals even though the agent may not be present in sufficient quantity to cause disease. In this study, nucleic acids of all 3 organisms contained in the IN vaccine were amplified from both sites on multiple days via PCR, although no clinical signs of respiratory disease were observed. Thus, interpretation of PCR panel results for diagnoses should include consideration of recent vaccination status and clinical signs of disease. Use of quantitative PCR and wild‐type sequence differences may be able to differentiate between vaccine and pathogenic agent shedding and may be used diagnostically in the future.
Real‐time reverse transcriptase PCR has been used to amplify canine distemper virus RNA in blood, urine, and conjunctival swabs after administration of SQ MLVx.10 In this study, the PCR panel did not amplify distemper virus RNA from nasal or pharyngeal swabs. Further studies are needed to determine whether the negative result is because this strain of vaccine virus does not reach the nasal or pharyngeal tissues or was present at levels below the detectable limit of the assay used.
RSV has three envelope proteins F, G, and SH. Both F and G are glycosylated and represent the targets of neutralizing antibodies. The RSV F protein emerged as a good vaccine candidate due to its conserved and vital role in cell attachment. Passive immunization is a direct approach to counter RSV (Figure 5). Initially, polyclonal antibodies from healthy human individuals resistant to RSV were successful in preventing RSV infection in high risk infants and these pooled and purified immunoglobins were popular as RespiGam. The monoclonal antibody specifically neutralizing F protein conferred effective protection against RSV as compared to RespiGam, and this licensed monoclonal antibody, palivizumab (Synagis), is now used to passively protect high risk infants from severe disease, thus replacing the RespiGam. The efficacy of the recombinant monoclonal antibody, palivizumab, has been tested for prophylaxis and therapy in immunocompromised cotton rats. Repeated doses of palivizumab were required to prevent rebound RSV replication. Palivizumab is administered alone or in combination with aerosolized ribavirin. Palivizumab cannot cure or treat serious RSV disease but neutralization of RSV can help in preventing serious RSV infections. Motavizumab has been found to neutralize RSV by binding the RSV fusion protein F after attachment to the host, but before the viral transcription. Viral entry was not inhibited by palivizumab or motavizumab when pretreated with RSV, but there was a reduction in viral transcription, thus inhibiting both cell-cell and virus-cell fusion most likely by preventing the conformational changes in the F protein needed for viral fusion.
The effective use of palivizumab is limited due to the cost and its use in infants with high risk of bronchiolitis based on the coverage by different healthcare systems. In spite of these restrictions on palivizumab, it has a wide societal impact on use in infants with chronic lung disease due to premature birth or those with haemodynamically significant cardiac disease. According to the modified recommendations of the Committee on Infectious Diseases of the Centers for Disease Control and Prevention of RSV, palivizumab is recommended for infants with congenital heart disease (CHD), chronic lung disease (CLD), and birth before 32 weeks. Minimum 5 doses are recommended irrespective of the month of the first dose for all geographical locations for infants with a gestational age of 32 weeks 0 days to 32 weeks 6 days without hemodynamically significant CHD or CLD. The new recommendations of the committee were aimed at the high risk groups including infants attending child care or one or more siblings or other children younger than 5 years living with the child. Also, the infants were qualified for receiving prophylaxis only until they reached 90 days of age. Palivizumab, although effective, is costly and thus is not beneficial to the recipients especially during the periods when RSV is not circulating. A cost effective means of producing RSV F neutralizing antibodies was experimented in phages and plants. Much success in this regard of palivizumab production was observed in the Nicotiana benthamiana plant system which offered glycosylation and high production at lower upstream and equivalent downstream cost, when compared to mammalian derived palivizumab. The efficacy of the plant derived palivizumab was more than the mammalian derived palivizumab or the plant derived human monoclonal antibodies in cotton rats.
Clinical signs observed including gasping, coughing or depression started to appear from three days post-challenge with APEC or a mixed APEC and IBV infection. Bacteriophage treatment delayed the onset of the clinical signs to 6 days post-challenge (dpc) and in addition markedly reduced their severity in both groups (Figure 3). Regarding IBV infection, clinical signs were observed from four-days post-challenge, with bacteriophage treatment leading to a reduction of their severity, but not delaying their onset (Figure 3).
Bacteriophage treatment was not associated with mortality in single APEC or mixed APEC and IBV infected groups. In contrast, birds challenged with APEC alone and mixed APEC and IBV infection without bacteriophage treatment showed a 16% and 29% mortality rate at 8 and 7 days post-infection respectively (Figure 4). Bacteriophage treatment in combination with single IBV infection did not reduce the mortality of 26% (Figure 4).
Bacteriophage treatment significantly reduced APEC shedding after single APEC or mixed APEC and IBV challenge, with a gradual decrease of bacterial loads in lung tissues over time. In contrast, a non-treated and challenged group showed a significantly higher APEC load with a gradual increase over time especially at 9 and 15 dpc (Figure 5). Interestingly, bacteriophage treatment significantly reduced IBV shedding in the mixed infected group but not in the IBV alone infected group comparing to the mixed infected group without bacteriophage treatment. The bacteriophage treated group infected with IBV showed relatively comparable results to the infected non-treated group. Groups with single IBV infection and mixed APEC and IBV infection with bacteriophage treatment showed a reduction, but not statistically significant, of IBV comparing to single IBV infection without bacteriophage treatment, with the reduction only becoming statistically significant at 15 dpc (Figure 6).
Currently, there is no vaccine or effective treatment against RSV, but the rapid and sensitive RSV detection is possible. The detection techniques are ameliorated by incorporating one or more methods and with the advancement in material science and biophysical capabilities, it has reinforced the development and design of RSV detection systems. However, an effective detection technique can be transformed into effective diagnosis by integrating it into the community health monitoring program at a reasonable cost. Prevention of RSV infection at present is limited to only high risk individuals with a limited efficacy. New preventive measures research like DNA vaccines, subunit vaccines, and nano-vaccines have reached animal trials. On the other hand, the RSV treatment approaches using antisense oligomers, fusion inhibitors, and benzimidazole drug have proceeded into clinical trials. The challenges associated with RSV management are categorically numerous. However, at the current pace of scientific research and development and with the implementation of scientific, commercial, and program recommendations to develop epidemiological strategies, it seems optimistic to have an effective diagnosis, prevention, and treatment solution for RSV in near future.
The intranasal route of drug administration has been frequently used to treat local conditions such as nasal congestion and allergy. Intranasal administration is characterized by easy administration, rapid onset of action and avoidance of first-pass metabolism. The needle-free administration route is non-invasive and can avoid the risk of spreading blood-borne infections, which is a particular problem in developing countries. These desirable features lead to the exploration of the systemic delivery of polar drugs or biomolecules including vaccines that are not feasible in other administration routes.
Intranasal vaccination has been investigated for over a decade. The majority of currently available vaccines are administered by intramuscular, subcutaneous or intradermal injection. Although these parenteral routes of administration are effective in inducing systemic immune responses, they are ineffective in inducing local immunity at mucosal sites. As many as 70% of pathogens infect human through the mucosal surfaces. Mucosal vaccination could provide better protection than injectable vaccines against infectious diseases by inducing both systemic and mucosal immunity. Since the strongest immune response is usually induced at the vaccination site and the adjacent mucosal sites, intranasal immunization is able to elicit protective immune response effectively in the lungs and the upper respiratory tract. Nasal mucosa appears to be an appropriate site of vaccine administration against respiratory infectious diseases, not only because the nasal cavity is the first site of contact with inhaled macromolecules and a common site of infection by respiratory pathogens, it can also stimulate respiratory mucosal immunity by interacting with the NALT. Current, licensed intranasal vaccines include FluMist®, a live-attenuated vaccine that targets influenza types A and B; and NASOVAC®, a live-attenuated vaccine that targets H1N1 influenza virus. Apart from live-attenuated vaccine, intranasal route of administration is also favorable to protein-based vaccination, as evidenced by many studies including the intranasal pneumococcal protein immunization against pneumonia, and a recent study on the intranasal respiratory syncytial virus (RSV) vaccine based on a recombinant fusion protein. With the success of intranasal live-attenuated virus vaccine and the promising effect of protein-based vaccine, it is highly plausible that DNA vaccines can adopt the same delivery route to achieve efficient immunization.
Some cats with mucopurulent nasal discharge maintain normal appetite and attitude and experience spontaneous resolution of illness within 10 days without antimicrobial treatment. The Working Group recommends that antimicrobial treatment be considered within the 10‐day observation period only if fever, lethargy, or anorexia is present concurrently with mucopurulent nasal discharge.
If antimicrobial treatment is chosen for a cat with acute bacterial URI, the optimal duration of treatment is unknown and so this recommendation is based on experiences of the Working Group members that are clinicians. The Working Group recommends empirical administration of doxycycline (Tables 1 and 2) for 7–10 days to cats with suspected acute bacterial URI as the first‐line antimicrobial option.27, 28 The Working Group believes that doxycycline is a good first choice because it is well tolerated by cats; most B. bronchiseptica isolates from cats are susceptible to doxycycline in vitro (by unapproved standards for testing), despite resistance to other agents such as beta‐lactams and sulfonamides,29, 30, 31 and doxycycline is effective in vivo for the treatment of cats with C. felis infections,27, 32, 33, 34 and Mycoplasma spp. infections.35 Doxycycline is also effective for the treatment of a variety of chlamydial and mycoplasma infections in cats and other mammalian host species. It also has activity against many opportunistic bacterial pathogens that are components of the normal microbiota of the respiratory tract. Of the 17 reviewers, 16 (94%) agreed with this Working Group recommendation and 1 disagreed because there is no breakpoint data for this antimicrobial for B. bronchiseptica or other bacteria in cats and there are no pharmacokinetics, controlled clinical trials, susceptibility data, or pharmacodynamic data on which to base the recommendation.
Due to delayed esophageal transit time for capsules and tablets, cats are prone to drug‐induced esophagitis and resultant esophageal strictures.36, 37 Although any table or capsule could cause this problem, doxycycline hyclate tablets and clindamycin hydrochloride capsules have been reported most frequently to cause problems.38, 39, 40 Thus, tablets and capsules should be given coated with a lubricating substance, followed by water, administered in a pill treat, concurrently with at least 2 mL of a liquid, or followed by a small amount of food.37 Doxycycline formulated and approved for use in cats is available in some countries and should be used if available. The use of compounded suspensions of doxycycline should be avoided because marketing of such formulations is in violation with regulations in some countries, including the USA. In addition, compounded aqueous‐based formulations of doxycycline are associated with a variable loss of activity beyond 7 days.41 Minocycline pharmacokinetics are now available for cats and this tetracycline should be evaluated further for efficacy against infectious disease agents in cats.42
The Working Group considers amoxicillin to be an acceptable alternate first‐line option for the treatment of acute bacterial URI when C. felis and Mycoplasma are not highly suspected. This is based on evidence that cats administered amoxicillin for the treatment of suspected secondary bacterial infections in shelter cats with acute bacterial URI often have apparent clinical responses.20, 43 Cats administered amoxicillin and clavulanate potassium (amoxicillin–clavulanate) had apparent clinical responses in 1 study of shelter cats with acute bacterial URI and so this drug also could be considered as an alternative to doxycycline in regions where a high prevalence of beta‐lactamase‐producing organisms has been identified (eg, based on regional antibiograms).44
In 1 study of shelter cats with suspected bacterial URI, the injectable cephalosporin, cefovecin was inferior to doxycycline or amoxicillin–clavulanate.44 One limitation of this study was the lack of a negative control group.44 Thus, it is the opinion of the Working Group that more evidence is needed before cefovecin can be recommended for the treatment of bacterial URI in cats (Table 2).
Focussing on upper respiratory tract samples (nasal and tonsillar swabs), viral nucleic acids were detected in 31 of 214 diseased dogs (14.5%). Sixteen dogs tested positive for CRCoV (7.5%), 14 dogs for CPiV (6.5%) and one of these dogs additionally for CAV‐2‐specific nucleic acid (0.5%). One single dog tested positive for CDV‐specific nucleic acid (0.5%). In none of the obtained samples from the upper respiratory tract was CIV‐specific nucleic acid detected. Of those 31 positive dogs, 21 were privately owned (group A), and 10 kept in shelters (group B). They consisted of five puppies, 12 adolescent dogs and 14 adult dogs. Twenty‐seven of the 31 positive dogs (87.1%) showed acute onset of signs, three suffered from chronic disease (9.7%) and for one diseased dog this information was not available (Table 2).
Furthermore, upper respiratory tract samples from two dogs (4.0%) of the clinically healthy control group C tested positive for CRCoV‐specific nucleic acid (Table 2).
Nine dogs from group A (5.2%) and seven dogs out of group B (17.0%) tested positive for CRCoV in either nasal, tonsillar or both samples at one time. One of these dogs belonged to the subgroup of puppies; nine dogs were from the adolescent subgroup and six animals from the subgroup of adult dogs. With one exception, all these animals showed acute onset of CIRD (93.7%).
Fourteen diseased dogs (6.5%) tested positive for CPiV. From those, 11 belonged to group A and three to group B. They all harboured CPiV‐specific nucleic acid in sample material from the nose and one dog concurrently from the tonsils. Four of these dogs were classified as puppies; three dogs were from the adolescent subgroup and seven dogs were adults. Twelve out of these 14 animals showed acute onset of clinical signs (85.7%), one dog was chronically ill, and for another dog this information was not available. Seven dogs (50.0%) were regularly vaccinated‐including against CPiV.
In one of these 14 CPiV‐positive dogs, CAV‐specific nucleic acid was detected concurrently. This dog was privately owned (group A) and tested positive for CAV in both nasal and tonsillar swabs and CAV‐2 strain (Toronto) was confirmed by DNA sequencing. Belonging to the subgroup of adults this dog had been irregularly vaccinated and received its latest vaccine 45 days before sample collection. It presented with a several week history of clinical signs including severe coughing, nasal and ocular discharge, dyspnoea and fever. Apart from that case, in no other dog was viral nucleic acid of two or more different viruses detected. In addition, no other proband of the study tested positive for CAV.
One dog from group A tested positive for CDV‐specific nucleic acid in a sample retrieved from the tonsils. RNA sequencing enabled the identification of a CDV vaccine strain (Onderstepoort). The dog was an adult and presented with chronic respiratory disease but no other signs consistent with CDV infection. The vaccination status of this dog was unknown.
Additional information regarding all PCR‐positive dogs is summarised in Table 3.
All BALF samples collected from 31 chronically ill dogs revealed negative PCR results.
For detection of antibodies against betacoronaviruses, 30 acute serum samples as well as the corresponding sera (obtained 2 to 3 weeks later) of the convalescent dogs were examined by an indirect immunofluorescence test. Madin‐Darby bovine kidney cells were disseminated on 96‐well microtitre plates (100 μL/well) and then incubated at 37°C in a humid 5% CO2‐atmosphere overnight. After washing the plates with phosphate‐buffered saline (PBS) solution, the adherent cells were infected with BCoV strain 15317/82 and incubated at 37°C for 48 hours. Subsequently cells were washed with PBS again and fixed with 100 mL of 96% ethanol.
The sera underwent twofold serial dilutions from 1:20 to 1:5120 with PBS and immunofluorescence test was performed as follows:
Ethanol was discharged, and the 96‐well microtitre plates were washed three times with PBS; 50 μL of the previously diluted sera per well were added and incubated at 37°C for 30 minutes. Thereafter, the plates were washed three times with PBS and 50 μL of 1:40 diluted fluorescein isothiocyanate (FITC)‐conjugate (anti‐dog IgG, Jackson) was added to each well. After incubation at 37°C for another 30 minutes and three washing cycles with PBS, 50 μL/well Eriochrome black T indicator (diluted 1:200 with PBS) was filled in each well of the 96‐well microtitre plate to reduce background fluorescence. Plates incubated for 5 minutes at room temperature before cells were washed three times with PBS once more. Finally, wells were filled with 50 μL/well of glycerine buffer solution to prevent the cells from drying.
For evaluation of the microtitre plates an inverse ultraviolet microscope was used. The highest dilution with a clear cytoplasmatic fluorescence was equivalent to the specific antibody titre of each serum sample. Samples that showed no fluorescence in dilution 1:20 were regarded as negative (no antibodies present). Each assay included a positive and a negative control serum.
About 70% of microbial agents causing outbreaks of emerging infectious diseases in humans originate directly from animals. Among respiratory virus infections, the influenza A viruses H5N1 and H7N9 from avian species, and the severe acute respiratory syndrome coronavirus from bats have caused large epidemics–. Atypical bacterial pathogens causing community-acquired pneumonia include Chlamydophila psittaci from psittacine birds and Coxiella burnetti from livestock and other animals. However, human outbreaks due to zoonotic bacteria associated with the emergence of a novel animal virus in the animal host were not previously documented.
In November 2012, an outbreak of human psittacosis affecting six staff members occurred at the New Territories North Animal Management Centre (NTNAMC) in Hong Kong. The human outbreak was preceded by an outbreak of avian chlamydiosis among the detained Mealy Parrots (Amazona farinose). Although birds in the tropical and sub-tropical areas are commonly infected with C. psittaci, most infected birds are asymptomatic,. Large human outbreaks are rare even among bird handlers. Although co-infection of C. psittaci and viruses has been reported in outbreaks of avian species–, no virus-bacterium co-infection of implicated avian species has ever been reported in outbreaks of human psittacosis. In this study, we sought to investigate viruses that cause avian co-infection, which may have led to this outbreak of psittacosis.
A case was defined as a staff member working at the NTNAMC who was hospitalized for respiratory tract infection between November 1 and November 30, 2012, and confirmed to have C. psittaci infection by polymerase chain reaction (PCR) and/or a four-fold rise in serum microimmunofluorescent antibody titer against C. psittaci (Focus Diagnostics, Cypress, California, USA).
Canine infectious respiratory disease complex (CIRDC) is a major cause of respiratory illness and morbidity. It is a complex condition for disease occurrence, involving multifactorial etiologies. Overcrowding, stress, age and other underlying factors result in interference with the dog's immune response and play a role in disease predisposition [2, 3, 4, 5, 6]. Infectious agents serve as a key factor in promoting the severity of a clinical symptom. The CIRD viruses (CIRDVs) that are commonly associated with CIRDC are canine parainfluenza (CPIV), canine distemper (CDV), canine adenovirus type 2 (CAdV-2), canine herpesvirus 1 (CaHV-1), canine respiratory coronavirus (CRCoV), and canine influenza virus (CIV) [1, 7, 8, 9].
During the last decade, novel viruses, such as canine pneumovirus (CnPnV) [10, 11] and pantropic canine coronavirus, which induce respiratory problems in dogs, have also been discovered. In addition, canine bocavirus [13, 14], canine hepacivirus and canine circovirus have been detected in respiratory tract samples of dogs showing respiratory illness, but the pathogenic roles of those viruses are poorly determined. Although new viruses have emerged, the common CIRDVs are still important contributors to respiratory disease [17, 18]. Additionally, current core vaccines that are routinely used in dogs prevent some CIRDVs, such as CPIV, CDV, and CAdV-2, but not CaHV-1, CRCoV and CIV. This lack of a vaccine for CaHV-1, CRCoV, and CIV is likely to allow the spread of infection.
Hospital-associated infection (HAI) has recently been described as an “ever-present risk”. The current literature includes reported outbreaks of CPIV and CaHV-1 in animal healthcare facilities, where these nosocomial infections worsened any ongoing disease and enhanced the morbidity and mortality rates. In addition, infections among communities are documented and serve as a source for disease dissemination. Community-acquired infections (CAIs) are those that are acquired without exposure to hospitals or with limited regular exposure with a health care center or both. Currently, CAIs with CIRDVs are believed to have a concomitant effect in respiratory disease [1, 21, 22, 23, 24].
The identification of multiple-viral-induced CIRDC involves the simultaneous rapid nucleic acid-based detection, typically by the reverse transcription polymerase chain reaction (RT-PCR) for RNA viruses and PCR for DNA viruses. These detection methods have led to an increased and better realization of the prevalence of CIRDC worldwide [3, 25, 26]. However, whether the severity of the respiratory disease depends on the number of viral infections is equivocal. Although epidemiological evidence of CIRDC has been reported periodically, the classification among HAIs and CAIs has largely not been evaluated [7, 24].
A comprehensive understanding of the source of infection (HA or CA) and other associated risk factors may help guide the successful implementation of preventive strategies. To emphasize this point, this study focused on the associations between the incidence of all six common CIRDVs, source of infection and the possible related risk factors of the dog's age, sex and vaccine status. Moreover, the relationship between clinical severity and number of viral infections was also evaluated in respiratory-ill dogs during 2013–2016 in Thailand.
All ethical issues including plagiarism, Informed Consent, misconduct, data fabrication and/or falsification, double publication and/or submission, redundancy, etc have been completely observed by the authors.
The bovine respiratory syncytial virus (BRSV) has been recognized as a pathogen in cattle responsible of an acute respiratory disease syndrome in beef and dairy calves since the early 1970s. The impact of BRSV infection on the cattle industry results in economic losses due to the morbidity, mortality, treatment and prevention costs that eventually lead to loss of production and reduced carcass value.
BRSV is an enveloped, non-segmented, negative-stranded RNA virus belonging to the Pneumovirus genus within the subfamily Pneumovirinae, family Paramyxoviridae. The BRSV virion consists of a lipid envelope containing three surface glycoproteins (glycoprotein [G], the fusion protein [F] and the small hydrophobic protein [SH]) (Figure 1). The envelope encloses a helical nucleocapsid composed by the nucleoprotein (N), the phosphoprotein (P), the viral RNA-dependent polymerase protein (L) the M protein and a transcriptional anti-termination factor known as M2-1. The genomic RNA (~15,000 nucleotides in length) also encodes an RNA regulatory protein M2-2 and two non-structural proteins, NS1 and NS2.
BRSV is closely related to human RSV (HRSV), and the epidemiology and pathogenesis of infection between these two viruses share some similarities and also many differences. The similarities between the two viruses have facilitated the unveiling of some of the mechanisms by which BSRV can cause disease. However, the means used by the virus to warrant transmission among individuals within and between herds have remained elusive.
Understanding of the global epidemiology and molecular epidemiology of BRSV has significantly improved over recent years. In this review, we discuss various aspects of the epidemiology and molecular epidemiology of BRSV as well as their relationship with viral evolution.
In order to determine at which stage AEBSF treatment blocks RSV A2 infection, we divided the treatment into three stages. At each stage, the medium was changed (Fig. 4a). Pre-inoculation treatment was limited to a treatment of 1 h before inoculation in DMEM without inactivated fetal bovine serum (iFBS) in order to block pre-existing active proteases. Peri-inoculation treatment was comprised of treatment during the 2 h inoculation phase which would inhibit proteases needed for attachment, fusion and uncoating. The post-inoculation phase started when the inoculum was removed 2 h post inoculation and replaced with complete medium. AEBSF was administered to the culture in a final concentration of 0.3 mM in each phase separately or in multiple phases. These time-of-addition experiments indicated that treatment only during the pre-inoculation phase did not result in a significant decrease of the RSV infection. Minor, but significant decreases were observed in the peri-inoculation only treatment, and the post-inoculation treatment only, as well as the combined treatment comprised of pre- and peri-inoculation treatment. Treatment that combines the post-inoculation phase with either the pre- or the peri-inoculation phase did result in a larger significant decrease of RSV infection. The combined peri- and post-inoculation treatment resulted in a nearly complete block that was comparable to the block observed in earlier experiments in which the treatment was comprised of pre-, peri- and post-inoculation treatment.
Given these results, we hypothesized that AEBSF needed to be present during the entry phase of RSV. In order to test this, we adapted the previous setup of the time-of-addition experiments to inoculation for 2 h at 4 °C to induce a more synchronized entry of the virion when the culture was shifted to 37 °C (Fig. 4b). Cells were placed at 4 °C 1 h prior to RSV infection to ensure a completely cooled culture. Cold inoculum was placed on the cells, followed by incubation at 4 °C for 2 h to allow attachment of the virus. Afterwards, the inoculum was removed, the cells were washed once with cold medium to remove unbound particles and complete medium at 37 °C was added to the cells to induce a temperature shift to 37 °C. Cells were further incubated at 37 °C for 18 h, fixed, stained and analyzed by fluorescence microscopy. Treatment during the peri-inoculation phase at 4 °C only did not result in a decrease in RSV infection which we considered normal since the cell metabolism is shut down at 4 °C and the virus particle only attaches at this temperature, however addition of AEBSF at the temperature change in the post-inoculation phase did result in a significant decrease of infected cells. This decrease is similar to the near complete block observed when AEBSF is present during combined peri-inoculation and post-inoculation treatment. These results confirm previous results and suggest that AEBSF treatment of RSV infection is most potent after the attachment of the virion to the host cell and before the start of replication.
The Paramyxoviridae family within the order of Mononegavirales includes a large number of human and animal viruses that are responsible for a wide spectrum of diseases. Measles virus (MV) is one of the most infectious human viruses known, and has been targeted by the World Health Organization for eradication through the use of vaccines. The paramyxovirus family includes several other viruses with high prevalence and public health impact in humans, like respiratory syncytial virus (RSV), human metapneumovirus (HMPV), mumps virus (MuV), and the parainfluenza viruses (PIV). In addition, newly emerging members of the Paramyxoviridae family – hendra and nipah virus – have caused fatal infections in humans upon zoonoses from animal reservoirs,,. In animals, Newcastle disease virus (NDV) is and Rinderpest virus (RPV) was among the viruses with the most devastating impact on animal husbandry. Members of the Paramyxoviridae family switch hosts at a higher rate than most other virus families and infect a wide range of host species, including humans, non-human primates, horses, dogs, sheep, pigs, cats, mice, rats, dolphins, porpoises, fish, seals, whales, birds, bats, and cattle. Thus, the impact of paramyxoviruses to general human and animal welfare is immense.
The Paramyxoviridae family consists of two subfamilies, the Paramyxovirinae and the Pneumovirinae. The subfamily Paramyxovirinae includes five genera: Rubulavirus, Avulavirus, Respirovirus, Henipavirus and Morbillivirus. The subfamily Pneumovirinae includes two genera: Pneumovirus and Metapneumovirus
. Classification of the Paramyxoviridae family is based on differences in the organization of the virus genome, the sequence relationship of the encoded proteins, the biological activity of the proteins, and morphological characteristics,. Virions from this family are enveloped, pleomorphic, and have a single-stranded, non-segmented, negative-sense RNA genome. Complete genomic RNA sequences for known members of the family range from 13–19 kilobases in length. The RNA consists of six to ten tandemly linked genes, of which three form the minimal polymerase complex; nucleoprotein (N or NP), phosphoprotein (P) and large polymerase protein (L). Paramyxoviruses further uniformly encode the matrix (M) and fusion (F) proteins, and – depending on virus genus – encode additional surface glycoproteins such as the attachment protein (G), hemagglutinin or hemagglutinin-neuraminidase (H, HN), short-hydrophic protein (SH) and regulatory proteins such as non-structural proteins 1 and 2 (NS1, NS2), matrix protein 2 (M2.1, M2.2), and C and V proteins,.
Routine diagnosis of paramyxovirus infections in humans and animals is generally performed by virus isolation in cell culture, molecular diagnostic tests such as reverse transcriptase polymerase chain reaction (RT-PCR) assays, and serological tests. Such tests are generally designed to be highly sensitive and specific for particular paramyxovirus species. However, to detect zoonotic, unknown, and newly emerging pathogens within the Paramyxoviridae family, these tests may be less suitable. Development of virus family-wide PCR assays has greatly facilitated the detection of previously unknown and emerging viruses. Examples of such PCR assays are available for the flaviviruses, coronaviruses, and adenoviruses. For the Paramyxoviridae, Tong et al. described semi-nested or nested PCR assays to detect members of the Paramyxovirinae or Pneumovirinae subfamily or groups of genera within the Paramyxovirinae subfamily. Although these tests are valuable for specific purposes, nesting of PCR assays and requirement for multiple primer-sets are sub-optimal for high-throughput diagnostic approaches, due to the higher risk of cross-contamination, higher cost, and being more laborious.” Here, a PCR assay is described that detects all genera of the Paramyxoviridae with a single set of primers without the requirement of nesting. This assay was shown to detect all known viruses within the Paramyxoviridae family tested. As the assay is implemented in a high-throughput format of fragment analysis, the test will be useful for the rapid identification of zoonotic and newly emerging paramyxoviruses.
Two new polyomaviruses were identified in 2007 in respiratory tract samples following large scale molecular screening using high throughput DNA sequencing of random clones and have been named after the institutes where they were found: KI (Karolinska Institute) polyomavirus (KIPyV) and WU (Washington University) polyomavirus (WUPyV). Data on seroprevalence indicate that infection is widespread ranging from 54.1 and 67% for KI and from 66.4% and 89% for WU in North American and German blood donors. Since their first identification, KI and WU viral sequences have been confirmed worldwide in respiratory samples from children with respiratory tract disease ranging from 0.2% to 2.7% and from 1.1 to 7%, respectively. However WUPyV and KIPyV were found at similar frequencies in control groups without respiratory diseases so the link between these polyomaviruses and acute respiratory diseases remains speculative.
Careful analysis is complicated by high co-infection rates with other well-characterized viral respiratory pathogens. A co-detection rate of 74% has been observed for KIPyV and rates ranging from 68 to 79% for WUPyV. Therefore, in a recent study in Southern China, hospitalized children with WUPyV infection displayed predominantly cough, moderate fever, and wheezing, but were also diagnosed with pneumonia, bronchiolitis, upper respiratory tract infections and bronchitis. As in most of infected children a single WUPyV infection was detected, it was suggested that the newly described polyomavirus can cause acute respiratory tract infection with atypical symptoms, including severe complications. Nevertheless these data have to be confirmed in further studies.
The presence of WUPyV and KIPyV in samples from children but not from immunocompetent adults suffering from LRTIs suggests that these viruses primarily infect the young population. A correlation between immunosuppression and reactivation of the two novel polyomaviruses has been suggested in immunocompromised patients and in AIDS patients at the molecular level, but no evidence of a role of these viruses as opportunistic pathogens has been given.
Overall, these data support the hypothesis that, in analogy with BK and JC polyomaviruses, KIPyV and WUPyV can establish persistent infection, and that virus replication may increase in immunocompromised hosts. However, in a recent study on immunocompetent and immunocompromised adult patients, real-time PCR detected KIPyV and WUPyV in 2.6% and 4.6% of HIV-1–infected patients respectively and in 3.1% and 0.8% of blood donors respectively, while no association was found between CD4+ cell counts in HIV-1 positive patients and infection with KIPyV or WUPyV.
KIPyV and WUPyV are also incidentally detected in adults with community acquired pneumonia, in immunocompromised hosts, and in patients with lung cancer; they are more often found in patients suffering an underlying medical condition and coinfections with KIPyV and WUPyV with other respiratory viruses are common. A recent study evaluating the prevalence and viral load of WUPyV and KIPyV in respiratory samples from immunocompromised and immunocompetent children showed that the prevalence of WUPyV and KIPyV is similar in hematology/oncology patients compared with that of the general pediatric population. High co-detection rates with other respiratory viruses, mainly RSV and enterovirus or rhinovirus, were found for WUPyV and KIPyV in both groups, in analogy with previous reports. However, higher viral loads for KIPyV in the immunocompromised group were detected, suggesting that there may be an increased replication of this virus in this population.
A similar association was not observed for WUPyV. Furthermore, in the immunocompromised group, infection with either virus occurred in older children compared with controls, which may indicate viral-reactivation Table 1.
As with other pathogenic infections, RSV initially activates the innate response and subsequently develops cellular and humoral immunity. The cellular immunity is needed to clear the infection, whereas the humoral immune response (antibody mediated) is required for protection from initial and subsequent RSV infections. During the 1960s, vaccinations performed with FI-RSV suggested that FI-RSV immunization leads to a predominant Th2 type allergic response. Whereas wild type RSV activates T helper type 1 (Th1) skewed immune providing protection against RSV disease. Thus, the Th1 type immune response is desired for protection against natural RSV infections. To understand the mechanism and type of immune responses for FI-RSV immunizations, different animal models such as monkeys, bovine, mice, and cotton rats [23, 32] were tested. All models challenged with wt RSV following the immunization with FI-RSV stimulated the Th2 type allergic response [23–25, 29–32]. In contrast, animals immunized and challenged with wt RSV developed Th1 type antibody protection against RSV. Likewise, natural RSV infection produces a Th1 mediated immune response against RSV. However, the most desirable immunity against any kind of pathogen is a balanced Th1/Th2 response. Even though the exact mechanism of FI-RSV mediated enhanced disease was not fully understood, Murphy et al. suggested that formalin treatment altered the protective epitopes of F and G proteins and failed to produce neutralizing antibodies against real RSV infections. They also reported that the sera from FI-RSV immunized recipients did not neutralize RSV in vitro due to the lack of RSV specific neutralizing antibodies compared to the sera from wt RSV immunized recipients. Consequently, the native form of RSV F is required to produce neutralizing antibodies and provide immunization against RSV infections. DNA vaccines are thought to be more advantageous due to the processing of antigens in their native forms by eukaryotic cells and due to the efficient presentation of antigens to antigen presenting cells. Thus, antibodies produced against the recombinant antigen expressed in the target host would easily recognize native nondenatured proteins of the pathogen and provide more efficient and specific protection against real pathogens compared to the recombinant protein vaccines expressed in bacteria. In a previous study, we developed a DNA vaccine containing a region of RSV F (412–524 amino acids) conjugated with a modified cholera toxin gene and used to immunize mice which resulted in higher immune response.
As mentioned in the FI-RSV vaccine trial, the native form of the RSV F protein is very crucial in stimulating the protective immune response against RSV. Major structural changes in the RSV F protein may lead to disease exacerbation and allergic outcomes. The RSV F DNA vaccine is a preferred immunogen compared to the recombinant RSV F protein produced ex vivo. For DNA vaccinations, the intramuscular injection route is the best route that ensures antigen expression and native conformation. Besides the native structure, another advantage of DNA vaccination is that it elicits the Th1 biased immune response due to its endogenous expression and presentation to the immune cells, which is a favorable response for protection from pathogens [13, 34]. The Th1 immune system and the production of neutralizing antibodies are very important for protection from reinfection, which confers long term immunity by recruiting memory B cells. When the host encounters the same pathogen again, memory B cells abruptly produce pathogen specific neutralizing antibodies and immediately inactivate the pathogen before it enters into the host and starts infection. We tested the ability of serum collected from RSV F immunized mice to neutralize RSV in vitro. Previous studies have shown that serum from FI-RSV infected mice does not neutralize RSV infection due to the altered structure of the RSV F protein.
Based on previous studies, distinct administration routes of the DNA vaccine evoke different types of immune responses. Our study was designed based on the previous DNA vaccine study where intramuscular injection of a DNA vaccine stimulated a moderate T cell response and antibody production compared to the oral administration, which induced a strong T cell response and weak antibody response.
RSV vaccine development has been hampered by the failure of previous vaccine trials that led to death of children. The main immunological event responsible of failure of the vaccine was induction of a predominant Th2 response that enhanced RSV disease following natural infection. Our study aimed at developing a safe DNA vaccine that induced a Th1 mediated antibody response. This study provides a basis for future RSV vaccine development that could benefit from DNA vaccine designs and may consider combination of DNA vaccine immunizations followed by traditional recombinant vaccine immunizations for higher protection from RSV infections.
Indirect enzyme-linked immunosorbent assay test (ELISA) was done to analyze the serum samples. Commercially available ELISA kits (BioChek®, Reeuwijk, Netherlands) of ART, ORT, ILT, and IBV were used to detect the antibodies. Serum samples were diluted at 1:50 dilution in dilution buffer, followed by 1:10 dilution, and final dilution of 1:500 was used as working samples for respective ELISA. 100 μl of negative and positive controls was added into antibody coated plate wells A1, B1 and C1, D1, respectively, remaining 92 wells were filled with samples. After that, plate incubated at room temperature for 30 min in case of IBV and 60 min in case of ART, ORT, and ILT. Meanwhile, conjugate and wash solutions were prepared according to manufacturer’s instructions. After incubation, contents of wells were aspirated and washed four times with wash buffer (350 μl). Then, the plate was inverted and tapped firmly on absorbent paper to remove the moisture. Then, 100 μl conjugate reagents were added on each well. Again, the plate was incubated for 30 min at room temperature in case of IBV and 60 min in case of ART, ORT, and ILT, respectively. After incubation, washed the plate with wash buffer following the procedure described previously. Then, the wells of microtiter plate were filled with substrate and incubated for 15 min at 22°C–27°C in case of IBV and 30 min for ART, ORT, and ILT. After incubation, the reaction was stopped by adding 100 μl stop solutions. Finally, the optical density value of each sample was measured at 405 nm within 15 min after adding stop solution, and the results were recorded by calculating sample to positive (S/P) ratio and antibody titer.
With the emergence of new or antimicrobial-resistant bacteria and viruses, and the ease of transmission, especially the respiratory pathogens, respiratory infections are becoming serious threats to human health. Safe and effective vaccines are important to safeguard public health. Intranasal DNA vaccination appears to be a promising non-invasive approach to provide protection against various infectious diseases. Evidence shows that intranasal DNA vaccine could elicit strong and long-lasting humoral as well as cell-mediated immune responses in many animal models. DNA vaccines are already successfully used in veterinary products for protection against infections, but their immunogenicity needs to be further enhanced to make them suitable for human use. Improving DNA delivery and formulation is one of the several strategies to enhance the immune response. Various studies have demonstrated that significant improvement of immune response that could be achieved by the employment of DNA carrier system, or to target the DNA vaccines to APCs. DNA vaccines generally have good safety profile, but the potential toxicity associated with DNA delivery systems, especially when they are used at high concentration, must not be neglected. DNA vaccines may circumvent many problems associated with conventional vaccines such as high costs of protein vaccine purification and bacterial/viral inactivated or attenuated process, the incorrect folding of antigen and viral mutation risk, thereby offering a safer alternative to benefit humans. In addition, mass manufacture of DNA vaccine is easier and faster, and DNA product is usually highly stable. Once an effective intranasal DNA vaccine delivery system is identified and optimized, a delivery technology platform could be established to allow the development of DNA vaccine formulations for different infectious diseases in the future.
The Working Group discussed whether antimicrobial treatment should be delayed while waiting until the results of culture and antimicrobial susceptibility testing are available. However, as not all clients can afford the diagnostic procedures and pneumonia can be a life‐threatening disease, the consensus opinion was to provide empirical antimicrobial treatment while waiting for test results with potential for de‐escalation of treatment based on antimicrobial susceptibility testing. While hospitalized, parenteral antimicrobial treatment is generally recommended by the Working Group for the treatment of animals with pneumonia, regardless of the severity of disease. Once the animal is discharged, treatment can be continued by means of the oral route. It is the opinion of the Working Group that doxycycline is a reasonable empiric choice for dogs or cats with mild pneumonia that is suspected to be from infection with B. bronchiseptica or Mycoplasma spp. (eg, the animal is from a shelter or boarding environment) and no other systemic signs of disease like fever, dehydration, lethargy, or respiratory distress are present. This is based on the known susceptibility of these organisms to doxycycline (see Section on Canine Infectious Respiratory Disease Complex) and published case reports of successful treatment with doxycycline (Table 2).74, 75, 78 Fifteen reviewers (88%) agreed and 2 (12%) disagreed with this Working Group recommendation. One reviewer stated that they doubted that pneumonia would be present without fever and if pneumonia exists, it should be treated with bactericidal drugs. The other dissenting reviewer commented on the lack of breakpoint data for doxycycline and the bacteria from dogs and cats as well as the concern that doxycycline might not penetrate into the extracellular fluids of the lungs.
Azithromycin is used by some veterinarians empirically in dogs with uncomplicated pneumonia, but the Working Group believes that data supporting this recommendation are lacking.
Streptococcus equi subspecies zooepidemicus strains isolated from dogs are susceptible to penicillin, amoxicillin, and ampicillin. Administration of amoxicillin–clavulanate is unnecessary if this organism is suspected because streptococci are not known to produce beta‐lactamases.90
Not all dogs or cats with acute aspiration pneumonia have a bacterial infection. However, aspirated bacteria can cause infection secondary to the chemical inflammation associated with aspiration. If the dog or cat is acutely affected and has no evidence of systemic sepsis, the Working Group believes that either no treatment or parenteral administration of a beta‐lactam antimicrobial like ampicillin, ampicillin‐sulbactam, or the first‐generation cephalosporin cefazolin might be sufficient (Table 2). Thirteen reviewers (82%) agreed, 3 were neutral (18%), and 1 (6%) disagreed with this Working Group recommendation. The primary comments were that the risk of not treating a case was greater than the perceived benefit of withholding treatment or that oral medications could be adequate for this syndrome. However, if megaesophagus or other esophageal motility disorders exist, parenteral administration of the antimicrobial drug is indicated.
If clinical findings in dogs or cats with pneumonia suggest the existence of sepsis (eg, injected mucous membranes, hypoglycemia), the Working Group recommends concurrent parenteral administration of either enrofloxacin or marbofloxacin (available in injectable form in some countries) combined with a drug with Gram‐positive and anaerobic spectra until bacterial culture and antimicrobial susceptibility testing results return. In 1 study, most bacteria from the lower airways of dogs with respiratory disease were susceptible to enrofloxacin.91 Other drugs for parenteral use with a Gram‐negative spectrum might be indicated in lieu of enrofloxacin based on culture and antimicrobial susceptibility testing (Table 2). The Working Group states that common options for Gram‐positive and anaerobic bacteria include ampicillin or clindamycin administered parenterally (Table 2). Which of these drugs to choose while waiting on antimicrobial susceptibility test results will depend on the most likely infectious agent suspected, previously prescribed antimicrobials (if any), and historical antimicrobial resistance in the geographical region. Fourteen reviewers (82%) agreed and 3 (18%) disagreed with this Working Group recommendation. The primary comment was that if Bacteroides spp. were present, clindamycin could be ineffective and that metronidazole could be considered another option.
Drugs that could be administered PO for outpatient treatment of bacterial pneumonia should be selected on the basis of culture and antimicrobial susceptibility results for organisms isolated from the lower airways, de‐escalating whenever possible. If culture and antimicrobial susceptibility testing was not performed, the antimicrobial drug class or classes that were initially prescribed and associated with clinical response is/are chosen for continued oral treatment.
Inflammatory responses to bacterial pneumonia increase pulmonary pathology. Thus, glucocorticoids are used concurrently in some human patients with bacterial pneumonia.92, 93 However, it was the consensus opinion of the Working Group that further data are needed from dogs and cats before a definitive recommendation can be made in regard to the use of systemic or inhaled glucocorticoids, which have the potential to contribute to adverse outcomes due to immunosuppression.
To address whether our results would apply to clinical isolates as well as the RSV A2 lab strain, we tested HEp-2 cultures infected with RSV A1998 3–2 and RSV A2000 3–4 clinical isolates for their sensitivity to AEBSF treatment (Fig 5). Cells were infected for 2 h at 37 °C in the presence or absence of AEBSF. The inoculum was removed and replaced with complete DMEM with or without AEBSF in the treated and control conditions respectively. Both clinical isolates show a minor decrease in the number of RSV positive cells when treated with 0.1 mM AEBSF and a significant large decrease when treated with 0.3 mM AEBSF, indicating that inhibition is probably a general feature of RSV.
HRVs are currently classified in the Picornaviridae family, genus Enterovirus, that includes 3 species: HRV-A, HRV-B, and HRV-C. Within each species there are multiple HRVs designated as “serotypes”, “types”, or “strains”. Several recent epidemiological studies suggest that HRV-A and HRV-C are the predominant species associated with acute respiratory illnesses in hospitalized children and adults, compared to HRV-B which are rarely detected.
The new HRV lineage designated HRV-C has been identified using molecular methods and associated with severe clinical presentations in infants and immunocompromised adults. Symptoms of patients infected with this new strain were mainly bronchiolitis, wheezing, and asthmatic exacerbation in cases from Australia and Hong Kong, which peaked in fall and winter whereas in New York the new rhinovirus genotype was detected in cases of influenza like illness (ILI) that were clustered within an 8-week period from October to December. A recent study describes a clinical case of severe respiratory and pericardial disease in an infant infected by HRV-C suggesting tha viral tropism is not strictly restricted to the respiratory tract. A study focusing on the global distribution of novel rhinovirus indicates its association with community outbreaks and pediatric respiratory disease also in Africa and in symptomatic subjects living in remote locations having limited contacts with other human populations. Moreover evidence for a role of HRV-C in lower respiratory tract disease and febrile wheeze in infants and asthma exacerbations in older children was reported. Recent studies making comparisons between HRVs species, found the HRV Cs more so than As or Bs as the major contributors to febrile wheeze and asthma exacerbation in infants and children, respectively . However, the severity of clinical manifestations for HRV-C is comparable to that for HRV-A in children with community-acquired pneumonia. In HRV C studies so far, no clear clinical difference has been noted between patients with single or mixed HRV-C infection. In a study, monoinfection was observed in more than half of cases and was more common than RSV monoinfection in patients with upper RTD, however the duration of hospitalizations was not significantly different between the HRV-C monoinfection group, HRV-A or HRV-B monoinfection group and RSV group suggesting that HRV-C is an important etiological factor in children with RTI. Most HRV-C co-detections are with RSV, however in a large study HRVs were statistically the least likely virus of 17 examined to be associated with co-infections Table 1.