Dataset: 11.1K articles from the COVID-19 Open Research Dataset (PMC Open Access subset)
All articles are made available under a Creative Commons or similar license. Specific licensing information for individual articles can be found in the PMC source and CORD-19 metadata.
More datasets: Wikipedia | CORD-19
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)
Funded by The Federal Ministry for Economic Affairs and Energy; Grant: 01MD19013D, Smart-MD Project, Digital Technologies
Clinical signs of classical swine fever usually appear 5–10 days after infection (occasionally longer). An individual pig may show one of four types of clinical effect; Peracute (sudden death, especially at the beginning of a farm outbreak), Acute (fever, depression, weakness, anorexia, conjunctivitis, diarrhoea or vomiting, purple discoloration of abdominal skin, or necrosis of the tips of extremities, and neurological signs), Chronic (weight loss, hair loss, dermatitis, discoloration of abdomen or ears) and subclinical. Affected pigs may recover or relapse, depending on the severity of the disease. Reproductive effects is also common; abortions, stillbirths, mummifications and also congenital tremor of piglets.
Clinical examinations were performed on Dogs 1 to 13 (Table 1); Dog 14 could not be examined because of aggressive behaviour. The clinical examinations revealed mucous, purulent or bloody ocular and/or nasal discharge (39 %), fever (31 %), coughing (31 %), inspiratory increased lung sounds (31 %), conjunctivitis (23 %), fluid-filled bowel loops (23 %), paleness (15 %), and lameness, tachypnoea, diarrhoea, dehydration, cachexia, otitis externa and vaginal discharge in single dogs (Table 1). The clinical examinations were unremarkable in Dogs 12 and 13.
Canine distemper (CD) is a highly contagious and fatal disease of dogs caused by the canine distemper virus (CDV), which is a single-stranded negative RNA virus belonging to the Morbillivirus genus within the Paramyxoviridae family. Other members of the genus include measles virus (MV) and rinderpest virus (RPV). The genome of CDV is approximately 15,690 nucleotides (nt) in length, containing several genes encoding N, P, M, F, H, and L proteins. Only one serotype has been characterized.
A large number of dogs, minks, foxes die from CDV infections every year, causing significant economic losses. Previous studies[3,4] have reported that vaccinated dogs were infected with CDV in Europe and Japan. Harder et al. also reported that there are marked differences between wild-type and vaccine strains of CDV, thus whether CDV vaccine strains are able to provide protection from the current strains of CDV remains a question. It is difficult and necessary to discriminate between wild-type and vaccine strains because the attenuated CDV vaccine is used widely in China. So a method to specifically detect the wild-type CDV strains is necessary. The multiplex reverse transcription-nested polymerase chain reaction (RT-nPCR) method could be used to effectively detect and differentiate between wild-type CDV-infected dogs from dogs which were vaccinated with CDV vaccine, which would make it useful in clinical diagnosis and epidemiological monitoring.
Feline herpesvirus type 1 (FHV-1; felid herpesvirus 1 (FeHV-1), family Herpesviridae, subfamily Alphaherpesvirinae, genus Varicellovirus) is an important pathogenic agent that causes feline viral rhinotracheitis, which is a highly infectious upper respiratory tract infection of felids. This infection is often fatal to kittens, but adult cats usually survive and exhibit lifelong latency. Since the first strain of FHV-1 was isolated in America, infected felids have been reported in many countries, including Canada, Switzerland, the United Kingdom, Holland, Hungary and Japan. There have been no documented reports on FHV-1 in the past few years, although the distribution in China was confirmed by serological survey and virus isolation in domestic cats.
The South China tiger (Panthera tigris amoyensis) is a tiger unique to China and is the most endangered tiger subspecies, as free ranging individuals have not been found in its historic distribution areas for many years. To aid in the recovery of wild populations, it is common to re-introduce captive individuals into their native range; however, there are fewer than 120 captive South China tigers in China. Furthermore, only a few captive tigers are suitable for reintroduction, and infectious diseases threaten captive tigers. Any sign of disturbance or trouble with the captive populations, in particular any risk of infectious disease, will greatly concern the stakeholders.
In June 2012, a South China tiger in Shenzhen Wildlife Zoo presented with sneezing, purulent rhinorrhea, which ended with its death, although treatment including antibiotics had been tried. In the present study, we used molecular methods, virus isolation, TEM examination and an animal challenge experiment to diagnose the cause of death of the South China tiger, and for the first time, we confirmed the infection with FHV-1 in the captive tiger population in China.
Border disease is an important disease in sheep, caused by infection of the foetus in early pregnancy. Surviving lambs are persistently viremic, and the virus is present in their excretions and secretions, including semen. Ruminants and possibly also pigs can be readily infected by contact with these persistent excretors or with acutely infected sheep. Acute infections in immunocompetent animals usually are transient and subclinical and result in immunity to challenge with homologous but not heterologous strains of virus. The disease is characterised by low birth weight and viability, poor conformation, tremor, and an excessively hairy birth coat in normally smooth-coated breeds. Kids may also be affected, and a similar condition occasionally occurs in calves. The disease has been recognized in most sheep-rearing areas of the world.
Haematology and blood biochemistry results were available for 13 dogs (Tables 2 and 3), 11 of which were CDV-PCR positive (Dogs 1 to 11, see below). At initial presentation, anaemia (9/13, 69 %), leucocytosis (8/13, 62 %), eosinophilia (8/11, 73 %), neutrophilia (6/11, 55 %) and monocytosis (5/12, 42 %) were common (Table 2). Dogs 3 and 4 showed severe pancytopenia and moderate bicytopenia, respectively; both were CDV PCR-positive, co-infected with Babesia spp. (Dog 3) or positive for anti-Leishmania infantum antibodies (Dog 4, see below), and they exhibited fever, increased inspiratory lung sounds, purulent ocular and nasal discharge and radiographic signs that were compatible with bronchopneumonia (Tables 1 to 5). Dog 8 showed slight anaemia and leucopenia (Table 2); this animal was co-infected with CDV and Babesia spp. (Tables 4 and 5). Dog 13 showed a pronounced eosinophilia (Table 2); this animal was CDV-PCR negative but Dirofilaria immitis positive (Tables 4 and 5). Blood biochemistry results revealed only unspecific changes in the dogs (Table 3).
Canine adenovirus (CAV) can be grouped into two distinct but related serotypes, CAV-1 and CAV-2, based on serological tests and molecular analyses [2–4]. Two types of Canine adenovirus (CAVs), Canine Adenovirus type 1 (CAV-1), the virus which causes infectious canine hepatitis, and Canine Adenovirus type 2 (CAV-2), which causes canine infectious laryngotracheitis, have been found in dogs. CAVs belong to the genus Mastadenovirus of the family Adenoviridae. Virus enters the host via direct contact with contaminated saliva, urine, and faeces. The incubation period is 4–7 days. CAV-1 replicates in vascular endothelial cells and causes a generalized infection characterized by hepatitis, whereas CAV-2 has an affinity for respiratory tract epithelium and is mainly associated with outbreaks of respiratory disease in kenneled dogs. CAV-1 causes fever, often above 40°C, apathy, anorexia, abdominal pain, blood in faeces, acute/chronic hepatitis and interstitial nephritis, tenderness, vomiting, and diarrhoea. Dogs may develop bronchopneumonia, conjunctivitis, photophobia, and a transient corneal opacity, “blue eye”, which may occur after clinical recovery as result of anterior uveitis and oedema [9, 10]. CAV-2 is characterized by respiratory disorders, with clinical signs that include tonsillitis, pharyngitis, tracheitis, and bronchitis [11–13]. Confirmation of diagnosis and identification of CAV-1 and CAV-2 infections are usually based on virus isolation, electron-microscopic observation and serological tests. There are distinct differences in structure, antigenicity, and pathogenicity between the two CAVs. Serological tests such as haemagglutination inhibition (HI), serum neutralization (SN), and enzyme-linked immunosorbent assay (ELISA) have been used detection of CAVs [15, 16]. The ELISA was found to be a highly efficient and rapid test to determine the immune status of dogs to infectious canine hepatitis virus and canine adenovirus type 2. The ELISA is a sensitive, reliable and fast method for the detection of anti-adenovirus antibody. When compared with SN test, the ELISA has several advantages. It does not require cell culture, the risk of contamination is less and the optimization is easier than other serological test methods. With the advent of molecular techniques, restriction endonuclease analysis (REA) of the viral genome has been said to differentiate between the two viruses [11, 14, 17].
The objective of this study was to determine the presence of antigen and the prevalence of CAV type 1 and 2 exposure in shelter-housed and household dogs in several regions of Turkey.
The caliciviruses (family Caliciviridae) are non-enveloped, positive sense, single-stranded RNA viruses with diameters ranging from 27 to 40 nm. Caliciviruses cause a wide range of significant diseases in human and animals. At present, there are five recognized genera, i.e., Norovirus, Sapovirus, Lagovirus, Vesivirus, and Nebovirus with several additional candidate genera or species proposed and under evaluation by the International Committee on Taxonomy of Viruses (ICTV) [1, 2] (http://www.caliciviridae.com/unclassified/unclassified.htm). In the Vesivirus genus, Vesicular exanthema of swine virus (VESV) and Feline calicivirus (FCV) are two species currently approved by ICTV. Several canine caliciviruses (CaCV) isolates have been identified and shown to be phylogenetically related to vesiviruses with features distinct from both VESV and FCV in phylogeny, serology and cell culture specificities. CaCV is a probable species in the Vesivirus genus, as stated by ICTV. It is still unclassified to date and the evidence presented herein should facilitate the classification and acceptance of CaCV as a species of vesivirus.
Many viruses found in human and other animal species can also infect dogs asymptomatically or cause respiratory, digestive, neurologic and genital diseases with mild to severe symptoms. In response to the use of dogs in military services and laboratory studies, etiological studies of canine diseases were conducted in 1963–1978 at the Walter Reed Army Institute of Research (WRAIR) [3, 4]. In addition to several known canine viral pathogens [5, 6], four unidentified viruses were recovered in Walter Reed Canine Cells (WRCC) producing similar cytopathic effects (CPE). The isolates were not recognized by available human and dog reference virus antisera. Studies of their physicochemical properties and electron microscope observations identified the isolates as likely caliciviruses. Our recent whole genome sequencing of these canine isolates clearly identified them as vesiviruses and elucidated their genetic relationships to the other members of the Caliciviridae family. We herein report the viral isolation and characterization results, which were made in 1963–1978 canine diseases etiological study but were not published, and additional genomics analysis supporting the serological diversity of CaCV strongly suggesting that these isolates and similar CaCV are a unique species within Vesivirus genus [7–9].
Canine enteritis can be caused by a number of viral, bacterial or parasitic agents. The most common viral entero-pathogens are canine parvovirus (CPV) and coronavirus (CCoV),, although other agents, such as canine adenovirus (CAdV) type 1, canine distemper virus (CDV), rotaviruses, reoviruses, and caliciviruses, have been associated with enteric disease in dogs. In recent years, novel viruses have been discovered from dogs with enteritis, namely noroviruses, sapoviruses, astroviruses, and kobuviruses,.
More recently, a dog circovirus (DogCV) was detected in dogs with vasculitis and/or hemorrhagic diarrhoea in the US (13). Circoviruses (family Circoviridae, genus Circovirus) are non-enveloped, spherical viruses with a small monomeric single-strand circular DNA genome of about 2 kb in length. According to the most recent release of the Universal Virus Database of the International Committee on Taxonomy of Viruses, the genus Circovirus consists of eleven recognized species, including Porcine circovirus 1 (PCV-1), Porcine circovirus 2 (PCV-2), Canary circovirus (CaCV), Beak and feather disease virus (BFDV), and other viruses of domestic and wild birds (http://ictvdb.bio-mirror.cn/Ictv/fs_circo.htm). Porcine and avian circovirus infections are characterized by clinical courses that may vary from asymptomatic infections to lethal disease.
Two independent studies have shown that, similar to other animal circoviruses, DogCV possesses an ambisense genomic organization with 2 major inversely arranged ORFs encoding for the replicase and capsid proteins, respectively,. The canine virus, firstly detected in serum samples, was later recognized as causative agent of necrotizing vasculitis and granulomatous lymphadenitis.
The aim of this paper is to report the detection and molecular characterisation of DogCV in dogs with acute gastroenteritis in Italy. The full-length genome of the Italian prototype strain was determined and analyzed in comparison with American strains and other circoviruses.
In canine disease, viral diarrhea has a high incidence because of etiology complexity, which causes serious harm to the canine industry and dogs. At present, several viral pathogens are related to canine diarrhea in China, including canine parvovirus (CPV) (1, 2), canine coronavirus (CCoV), canine bocavirus, canine kobuviruses (CaKVs), and canine distemper virus (CDV). CPV is an important cause of mortality and morbidity in dogs, especially puppies, in China and the rest of the world (3–5). Variation, recombination, and coinfection have been shown to aggravate clinical symptoms and challenge the prevention and control of CPV infections (6–9). Dogs that become infected by CPV show illness within 3–7 days, presenting with severe gastroenteritis, lethargy, vomiting, fever, and diarrhea (usually bloody) (10–12).
CPV belongs to the genus Parvovirus, family Parvoviridae, and causes a highly contagious and fatal disease in dogs (1). The original viral strain, designated as CPV-2 to distinguish it from CPV-1 which is also known as canine minute virus and was believed to be non-pathogenic until 1992 (13). CPV-2 is a non-enveloped DNA virus with a linear single-stranded DNA genome (5.2 kb), containing two major open reading frames (ORFs). One ORF encodes the two non-structural proteins (NS1 and NS2), and the other encodes the two capsid proteins (VP1 and VP2) (14). The VP2 protein of CPV-2 is known to affect antigenic properties, playing important roles in controlling viral host ranges and tissue tropisms (15–17).
The main method for controlling the virus in domestic animals is by vaccination, antibody therapy, and traditional Chinese medicine therapy (18, 19). However, the virus is widely distributed in nature, and the morbidity and mortality of CPV-2-infected animals remain high (20). Furthermore, because of vaccine formulations, a dramatic increase in the number of dog or other factors potentially promote the spread of different CPV-2 antigenic variants, increasing disease complexity (21–23). In previous studies, researchers have investigated CPV-2 genetic evolution (5, 24–27), providing important reference information for the prevention and control of the CPV-2 infections. However, the molecular epidemiology and genetic diversity of CPV-2 need to be updated in China. In this review, we have summarized contemporary data on the progression of CPV-2 epidemiology in China, including the virus origin, prevalence, coinfection, and evolution. The aim is to unravel CPV-2 epidemiology and provide new information on virus infections, not only for Chinese dogs and their owners but also for all dog owners across the world.
Pet dogs play an important role in humans’ daily lives. Recently, the emergence of new pathogens and the continuous circulation of common etiological agents in dog populations have complicated canine diseases. Among these diseases, canine infectious respiratory diseases (CIRD) and viral enteritis pose notable threats to dog health.
CIRD are complex and include canine adenovirus type 2 (CAV-2), canine distemper virus (CDV), canine influenza virus (CIV), canine parainfluenza virus (CPIV), canine herpesvirus (CHV), canine reovirus, Bordetella bronchiseptica and other pathogenic agents [2–4]. Among these, CAV-2, CDV or CPIV have frequently been detected in dogs with CIRD, according to previous studies [5, 6]. Avian-origin H3N2 CIV has been detected in domestic dogs in South Korea and China since 2007 [7, 8]. H3N2 CIV is now circulating in dog populations in China, South Korea, Thailand, and even the United States [9–11]. Distinguishing these pathogens can be challenging, because dogs often show similar clinical signs of infection with these viruses, such as low-grade fever, nasal discharge and cough. These respiratory symptoms are flu-like and difficult to diagnose.
Canine viral enteritis is common in dogs with acute vomiting and diarrhea. Canine parvovirus (CPV) is one of the major viruses leading to acute gastroenteritis in dogs; CPV infection is characterized by fever, severe diarrhea and vomiting, with high morbidity. Puppies tend to be intolerant of CPV infection and have higher mortality than adult dogs because of myocarditis and dehydration [14, 15]. Canine coronavirus (CCoV) is characterized by high morbidity and low mortality. Dogs infected with CCoV alone are likely to have mild diarrhea, whereas the disease may be fatal when coinfection by CCoV and CPV, CDV or canine adenovirus type 1 (CAV-1) occurs [16, 17]. CAV-2 is associated with mild respiratory infection and episodic enteritis [18, 19]. Canine circovirus (CanineCV), a newly discovered mammalian circovirus, was first reported by Kapoor et al. in 2012. CanineCV has been detected in dogs with severe hemorrhagic diarrhea, and it is more common in puppies than in adults [21, 22]. Coinfection of CanineCV with other intestinal pathogens (CPV or CCoV) is closely related to the occurrence of intestinal diseases [23, 24]. Dogs with intestinal diseases are often infected with one or more viruses, and their clinical symptoms are similar [17, 25, 26], making clinical differential diagnosis difficult. To date, no multiplex PCR (mPCR) method has been developed to detect CanineCV and other enteropathogens.
An effective diagnostic tool is important for the prevention, control and treatment of CIRD and viral-enteritis-related viral diseases. Although many methods exist to detect CIRD and canine viral enteritis, most can detect only 2 or 3 pathogens, and the current lack of systematic and comprehensive detection methods makes diagnosis impractical and time consuming [4, 27, 28]. Because mPCR can simultaneously detect multiple pathogens in a timely and inexpensive manner, this technique has become increasingly popular. Therefore, in this study, two new mPCR methods were developed for the detection of canine respiratory viruses (CRV, including CAV-2, CDV, CIV and CPIV) and canine enteric viruses (CEV, including CAV-2, CanineCV, CCoV and CPV), and we indicated that the mPCR methods established here are simple and effective tools for detecting the viruses of interest.
The recent epidemic of Ebola virus in Africa as well as the emergence of a hitherto unknown virus known as Middle East respiratory syndrome coronavirus (MERS-CoV), Bas-Congo virus in central Africa or of severe fever with thrombocytopenia syndrome virus (SFTSV) in China have repeatedly shown the global impact of emerging infectious diseases (EIDs) on economics and public health. These EIDs, more than 60% of which are of zoonotic origin, are globally emerging and re-emerging with increased frequency. Surveillance and monitoring of viral pathogens circulating in humans and wildlife and the identification of EIDs at an early stage is challenging. Many potential emerging viruses of concern might already be infecting humans or wildlife but await their detection by disease surveillance. In remote and underdeveloped regions of the world, often no attention is paid towards possible infectious disease cases until a threshold of serious cases and deaths appears in a cluster and certain epidemic properties are reached. Some viruses might just be overlooked at population levels until they spread or re-emerge and become epidemic in another region or time. An effective strategy in virus surveillance would need to survey simultaneously a wide range of viral types in a large number of human and wildlife individuals in order to detect viruses before spreading. For example, the EcoHealth Alliance within the surveillance program PREDICT seeks to identify new EIDs before they emerge or re-emerge. Therefore, wildlife animals that are likely to carry viruses with zoonotic potential, e.g., bats, rodents, birds and primates, are sampled frequently. However, collecting swabs or blood from sufficient numbers of wildlife individuals and the subsequent identification of viruses is challenging. The solution for overcoming this challenge might be presented by the disease vector itself. Blood feeding arthropods feed on blood from a wide range of hosts including humans, mammals and birds. Therefore, they act as “syringes”, sampling numerous vertebrates and collecting the viral diversity over space, time and species. Xenosurveillance and vector-enabled metagenomics (VEM) are surveillance approaches that can exploit mosquitoes to capture the viral diversity of the animal, human or plant host the mosquito has fed on (Figure 1). Xenosurveillance, a term introduced by Brackney et al., refers to the identification of viral pathogens from total nucleic acids extracted from mosquito blood meals, either by next-generation sequencing (NGS) or conventional PCR assays. Recent developments in NGS and viral metagenomics, which is the shotgun sequencing of viral nucleic acids extracted from purified virus particles, offer great opportunities for the characterization of the complete viral diversity in an organism or a population. VEM, a technique used to sequence purified viral nucleic acids directly from insect vectors, has already been used to detect both animal and plant viruses circulating in vectors. This review summarizes findings from xenosurveillance efforts as well as VEM studies using mosquitoes, since both approaches combine sampling of multiple individuals of blood-feeding arthropods with the high-throughput properties of NGS.
Contagious upper airway infections in dogs occur regularly and are most commonly caused by canine parainfluenza virus (CPIV) or Bordetella bronchiseptica, amongst other agents. This clinical syndrome has also been named infectious tracheobronchitis (ITB), canine infectious respiratory disease (CIRD), “kennel cough” or “kennel croup”, so named due to its occurrence in environments where many dogs live or stay close together for shorter periods of time. Characteristic clinical signs include a self-limiting paroxysmal cough lasting for up to two weeks, which usually resolves without treatment. In Norway, immunisation against CIRD is performed using live attenuated viruses, annually with CPIV and every third year against canine adenovirus type 2 (CAV-2). However, in spite of vaccination, outbreaks of CIRD remain common. Some dogs with CIRD will develop serious pneumonia due to an immature immune system or other causes of immunodeficiency. Occasionally, bacteria such as Streptococcus equi subsp. zooepidemicus can cause fatal pneumonia.
This case-report describes the first canine outbreak of haemorrhagic pneumonia in the Nordic countries caused by S. equi subsp. zooepidemicus. Most of the animals in the pack of athletic sled dogs showed symptoms of CIRD with three dogs demonstrating symptoms of severe peracute infection. One sled dog died while two were successfully treated, rehabilitated and returned to competition. To the author’s knowledge, this is the first report documenting the chronology from onset of clinical signs, through convalescence to complete recovery for peracute haemorrhagic pneumonia in dogs. The vaccination regimen related to season and extreme training will also be discussed.
Canine diarrhea is one of the most common illnesses treated by veterinarians with many possible causes of canine diarrhea, including bacteria, parasites, and viruses. One of the most important dog enteric viruses is canine parvovirus 2 (CPV-2) in the Carnivore protoparvovirus species 1. Parvoviruses are small, icosahedral, nonenveloped, single-stranded DNA viruses that are pathogenic to a variety of mammals. The vertebrate-infecting parvoviruses are classified in the subfamily Parvovirinae in the Parvoviridae family (which also includes the insect infecting subfamily Densovirinae). The Parvovirinae subfamily is currently subdivided into eight officially recognized genera (Dependoparvovirus, Copiparvovirus, Bocaparvovirus, Amdoparvovirus, Aveparvovirus, Protoparvovirus, Tetraparvovirus, and Erythroparvovirus). The recently proposed genus Chapparvovirus is currently comprised of a rat parvovirus 2 (KX272741), Eidolon helvum fruit bat parvovirus 1 (MG693107.1), and E. helvum bat parvovirus 2 (JX885610), Desmodus rotundus bat parvovirus (NC032097.1), simian parvo-like virus 3 (KT961660.1), Turkey parvovirus TP1-2012/Hun (KF925531), porcine parvovirus 7 (KU563733), murine chapparvovirus (MF175078), Tasmanian devil-associated chapparvovirus strains 1–6 (MK513528-MK53533), red-crowned crane-associated parvovirus (KY312548, KY312549, KY312550, KY312551), and chicken chapparvovirus 1 and 2 (MG846441 and MG846642). A close relative of murine chapparvovirus, initially reported in the feces of a wild Mus musculus from New York City, called murine kidney parvovirus (MH670588) was recently shown to cause nephropathy in immunocompromised laboratory mice. A recent survey of eukaryotic genomes for chapparvovirus sequences has also shown the presence of a likely exogeneous chapparvovirus genome in a fish (Gulf pipefish or Syngnathus scovelli) and of mostly defective germline sequences in another fish (Tiger tail seahorse or Hippocampus comes) as well as in multiple invertebrates, indicating an ancient origin for chapparvoviruses. A phylogenetic analysis of NS1 also indicated chapparvoviruses fall outside the traditional vertebrate-infecting Parvovirinae subfamily clade and closer to that of a subset of members of the subfamily Densovirinae.
Here an unexplained diarrhea outbreak among dogs was analyzed using viral metagenomics after diagnostic tests were negative for common canine enteric pathogens. The genome of a novel chapparvovirus was characterized and used to perform an epidemiological study to measure its prevalence and possible clinical significance.
Canine infectious respiratory disease (CIRD) is a multifactorial disease affecting dogs of all ages, which is typically induced by simultaneous viral and bacterial infections. Apart from well-known canine respiratory pathogens, such as canine adenovirus type 2, canine herpesvirus, canine distemper virus, and canine parainfluenza virus, novel viruses are being continuously associated with CIRD occurrence in dogs. These include canine influenza virus, canine respiratory coronavirus, canine pantropic coronavirus–, canine bocaviruses, and canine hepacivirus.
Pneumoviruses (family Paramyxoviridae, subfamily Pneumovirinae, genus Pneumovirus) are enveloped, single-strand negative-sense RNA viruses that are associated with respiratory disease in mammals and birds. Apart from the prototype species human respiratory syncytial virus (HRSV) and its ruminant relative bovine respiratory syncytial virus (BRSV), a murine pneumovirus (MPV), also known as pneumonia virus of mice, is included in the genus Pneumovirus
. This virus, which is only distantly related to human and ruminant RSVs, is a natural rodent pathogen circulating among research and commercial rodent colonies.
Recently, a pneumovirus was associated to respiratory disease in canine breeding colonies in the United States–. The virus, designated as canine pneumovirus (CnPnV), was found to be very closely related to MPV, displaying 95% nucleotide identity with the MPV prototype isolate J3666. Experimental infection of mice with the canine isolate demonstrated that CnPnV is able to replicate in the mouse lung tissue inducing pneumonia. Although the virus was discovered more than 4 years ago, to date there is no complete genomic sequence, which prevents a comprehensive comparative study with other members of the Pneumovirinae subfamily.
The aim of the present manuscript is to report the detection and molecular characterisation of this emerging virus in dogs with respiratory disease in Italy. The full-length genome of a prototype strain was determined and analysed in comparison with American strains and other pneumoviruses.
For the IG group cats, positive results appeared on the 6th day post-inoculation. PCR was used to detect FHV-1 DNA extracted from the specimens, which included nose washing fluid, eye swabs and swallow swabs. Positive results were found on the 10th day and 16th day for the EG group cats and the control cat, respectively (Table 1). These results revealed a baseline of virus shedding in the infected cats after they were inoculated or were exposed to FHV-1.
The incubation period of FHV-1 infection as indicated by this challenge test is approximately 6 days, which is consistent with that reported previously. Additionally, clinical signs, including pyrexia, inappetence, and serous ocular and nasal discharge, were observed in the cats, and a long period of virus shedding was observed.
On December 3, 2014, an eight-year old giant panda named Chengcheng presented with jaw trembling and violent convulsions of the limbs. Over the ensuing fourteen weeks, four additional giant pandas housed in the same room or adjacent rooms began to display clinical signs including mucopurulent ocular discharge, nasal and footpad hyperkeratosis, and violent convulsions of the limbs (clinical onset dates are listed in Table 1). Nucleic acids isolated from nasal swabs, urine, feces and blood collected from affected pandas at the time of clinical presentation all tested positive for CDV by RT-PCR. PCR-based tests were negative for other virus previously isolated from giant pandas (canine coronavirus) or viruses regarded as a potential threat to giant pandas (canine adenovirus, canine herpesvirus, and canine parainfluenza virus)41617. CDV-positive giant pandas were monitored and treated with antiserum therapy.
Each of the five CDV-infected giant pandas that displayed clinical signs of infection died 7–34 days following disease onset (Table 1). No CDV serum neutralizing (SN) antibodies were detected in the five infected giant pandas showing clinical signs of CDV infection prior to death (Table 1). However, CDV RNA was detected by RT-PCR in heart, liver, spleen, lung, kidney, intestines and brain of four deceased giant pandas (Table 2). In addition, CDV RNA was detected by RT-PCR from blood and nasal swab samples collected from an asymptomatic giant panda named Zhuzhu, who was previously vaccinated against CDV in 2012 and had high-titer SN antibodies (Table 1). None of the additional sixteen giant pandas in the Shanxi Rare Wild Animal Rescue and Research Center tested positive for CDV by RT-PCR. Uninfected pandas within the Shanxi Rare Wild Animal Rescue and Research Center were placed in isolation on December 26, 2014 and vaccinated with a canarypox-vectored CDV vaccine.
Blood serum samples belonging to 188 dogs, which had either been admitted to the Internal Medicine Clinic of Selcuk University, Faculty of Veterinary Medicine, with clinical symptoms or had been sampled at the dog shelters they were cared after in Isparta and Burdur provinces, were examined using the ELISA method. Of these samples, 103 (54.7%) were found to be positive for antibodies against CAV infection (Table 3).
Of the 108 female animals sampled in the study, 55 (50.9%) were determined to be positive for CAV antibodies, while 48 (60%) of the sampled 80 male animals were confirmed to be positive (Table 3). Of the 7 animals below 1 year of age, only 1 (14.2%; 2-month-old female puppy) was positive, and the remaining ones were found to be negative for CAV antibodies. Of the 53 animals aged 1-2 years, 22 (41.5%); of the 58 animals aged 2 years, 31 (53.4%); of the 64 animals aged 3 years, 44 (68.7%); and of the 6 animals aged >4 years, 5 (83.33%) were found to be positive (Table 2).
Blood leukocyte samples from dogs were processed and inoculated onto confluent monolayers of MDCK cells using standard virological techniques. The inoculated cells were incubated at 37°C and observed daily for the appearance of cytopathic effect (CPE). After third passage, cells were examined by immunofluorescence test for virus isolation. No morphological changes were observed in cell cultures, and a positive result was not detected by immunofluorescence test.
Clinical Findings. Blood samples were taken from 111 dogs showing clinical symptoms which were brought to the Internal Medicine Clinic of Selcuk University, Faculty of Veterinary Medicine. Seventy-seven dogs were sampled from Isparta and Burdur dog shelters by random sampling, regardless of the clinical findings. Dogs showed a systemic disease, characterized by fever, diarrhea, vomiting, mucopurulent oculonasal discharge, mucopurulent conjunctivitis, severe moist cough, signs of pulmonary disease, and dehydration. Corneal opacity and photophobia were determined for two dogs.
Fluid replacement, systemic antibiotic administration, antinausea medicines, antidiarrhea medicines, and a rigorous diet combined with monoclonal antibodies are the main treatment methods for CPV-2-infected dogs; however, the recovery rates vary from 27.8 to 93.5% (39, 53, 55, 56, 64, 65). Both disease and pathology of the infected animal differ depending on the age. CPV-2 infection in adult dogs results in temporary panleukopenia or lymphopenia; CPV-2 infection in neonatal animals causes myocarditis (12, 66). CPV-2 monoclonal antibodies are highly therapeutic in a short period of time and have treatment well effect (53). The cure rate for a CPV-2 single infection is higher than that of a coinfection with other viruses (41). With improvements in medical treatments, CPV-2 cure rates have been improved using specific drugs or other treatments.
Over the past few years, efforts have been made towards a better understanding of the health status of animal populations, particularly regarding viral infections. Due to their high mutation rate and replication strategies, viruses are responsible for recently recognized emerging diseases, posing a danger not only to domestic and wild animals, but also to humans.
The high density of domestic and stray animals in urban areas enables viral dissemination and maintenance in these populations. Consequently, these animals can act as reservoirs of diseases, with the possibility of transmission to wildlife populations through occasional contact.
Canine parvovirus (CPV) was first identified in the late 1970s and was responsible for severe hemorrhagic gastroenteritis and myocarditis in dogs. Parvoviruses are extremely stable in the environment and indirect transmission assumes a critical role in spreading and maintenance of the virus in animal populations, especially in wild carnivores, in which contact rates between animals are lower. Shortly after its initial detection, CPV-2 was replaced by two antigenic variants, CPV-2a and CPV-2b and more recently a third variant was described CPV-2c.
Canine distemper virus (CDV) is the etiological agent of canine distemper, a highly contagious disease, responsible for high mortality rates in dogs worldwide. Sequence analysis of CDV strains originated in different geographical areas from several animal species, showed that the hemagglutinin gene has undergone a genetic drift according to the geographic location. Phylogenetic analysis based on this gene revealed the existence of at least nine strains in different geographical areas, namely America-1, America-2, Asia-1, Asia-2, Europe-1/South America 1, European wildlife, Arctic-like, South America 2 and Southern Africa.
Canine coronavirus (CCoV) causes a mild to moderate enteritis in dogs and its infection is characterized by high morbidity and low mortality. CCoV is transmitted by faecal-oral route and spreads rapidly through a group of susceptible animals. Stressful environments with large concentrations of animals and poor hygienic conditions, often seen in kennels, favour the development of this disease. Although a higher mortality rate is observed in animals with multiple infections with other pathogens such as CPV-2, canine adenovirus type 1 and CDV, CCoV represents per si a major infectious agent responsible for several epidemics.
Virological surveys are conducted throughout the world, allowing the detection and analysis of a large variety of viruses in different animal populations. In Cape Verde archipelago to our knowledge, no similar study had been conducted so far. In order to detect the presence of canine viruses on Maio island, samples collected from stray dogs from Vila do Maio were tested for canine parvovirus (CPV), canine distemper virus (CDV) and canine coronavirus (CCoV), to estimate the viral prevalence in this population and investigate the role of these animals in the maintenance and potential spread of common viral pathogens.
Canine infectious respiratory disease (CIRD), synonymous for infectious tracheobronchitis or “kennel cough,” is a disease caused by single or multiple infectious agents with a high worldwide prevalence. Apart from several viral and bacterial agents, the individual health and constitution, vaccination status and environmental influences including husbandry conditions (e.g. crowding of animals) may have an impact on the manifestation of clinical signs. Non‐complicated forms of typically self‐limiting character may be distinguished from complicated forms associated with, possibly fatal, pneumonia. A severe course of disease typically develops as a consequence of coinfections (Chalker et al. 2003, Chvala et al. 2007, Schulz et al. 2014a). However, even isolated viral infections [e.g. canine influenza virus (CIV)] may lead to clinically relevant and sometimes lethal respiratory disease (Crawford et al. 2005). Commonly recognised viral causes of CIRD are canine parainfluenza virus (CPiV), canine adenovirus type 2 (CAV‐2) and canine distemper virus (CDV) (Ford 2012).
However, according to more recent studies, the understanding of this disease complex has changed. New viral pathogens have been detected within the past two decades. In 2003, canine respiratory coronavirus (CRCoV) emerged as a cause of CIRD in a rehoming centre in the UK (Erles et al. 2003). Further studies from several countries detected CRCoV‐specific nucleic acid in dogs suffering from respiratory disease (Yachi & Mochizuki 2006, Decaro et al. 2007, Spiss et al. 2012, Schulz et al. 2014a, Viitanen et al. 2015).
In association with an outbreak of respiratory disease in racing greyhounds in Florida, CIV types closely related to influenza subtype H3N8, originally detected in horses were isolated (Crawford et al. 2005). Subsequently, several studies from different countries detected CIV isolates in respiratory samples and concurrent anti‐CIV antibodies in dogs with mild respiratory signs as well as cases of fatal respiratory disease (Yoon et al. 2005, Daly et al. 2008, Payungporn et al. 2008, Song et al. 2008, Kirkland et al. 2010, Li et al. 2010, Song et al. 2013). Furthermore, isolation of human‐related influenza strains from dogs was successful (Lin et al. 2012). To date, at least seven influenza virus subtypes showing different ability of interspecies and intraspecies transmission have been isolated from dogs. These subtypes are mainly prevalent in the USA (H3N8), Eastern China and South Korea (e.g. H3N2), but some of them have also been reported from European countries (Sun et al. 2013, Xie et al. 2016) supporting the hypothesis that dogs may play a role in transmission and spread of influenza virus among animal species and even humans.
Detection of further viral pathogens (e.g. canine herpesvirus, canine reovirus, canine pneumovirus (CnPnV), pantropic canine coronavirus, canine hepacivirus and canine bocavirus) has been associated with respiratory disease in dogs (Buonavoglia & Martella 2007, Decaro & Buonavoglia 2008, Kawakami et al. 2010, Renshaw et al. 2010, Decaro & Buonavoglia 2011, Kapoor et al. 2011, Kapoor et al. 2012, Mitchell et al. 2013b, Priestnall et al. 2014). However, these viruses are uncommonly detected in dogs with CIRD or their possible role as causative agents is not yet completely determined.
The aim of this study was to assess the prevalence of common CIRD‐associated viruses (CPiV, CAV‐2, CDV) in dogs in and around Vienna, Austria. Although there may be environmental factors specific to this location, our findings are likely to generalise to other locations within Western Europe and possibly further afield. It was further investigated whether emerging viruses (CRCoV and CIV) have a significantly higher prevalence in dogs with CIRD compared to dogs without respiratory disease.
Canine infectious respiratory disease (CIRD) may be associated with single virus infections or with a multifactorial etiology and are assigned to infectious agents that replicate sequentially or in synergy.1 The main viral agents involved in CIRD include Canine distemper virus (CDV), Canine parainfluenza virus (CPIV), Canine adenovirus type 2 (CAdV-2) and Canid herpesvirus 1 (CaHV-1).2
In Brazil, CDV infection is endemic in dog populations, is associated with respiratory and/or multisystemic disease, and causes thousands of deaths each year.3, 4 Due to its impact on animal health, CDV is one of the most important infectious diseases in dogs.2, 5 Similarly to CDV, CAdV-2 has a worldwide distribution and is a major agent of canine infectious tracheobronchitis (CIT) or “kennel cough”, a disease characterized by restricted infection of the respiratory system.6 CPIV has a wide distribution in canine populations with an estimated seroprevalence ranging from 30 to 70%.7 CPIV infection is related to high population density; the virus is highly transmissible and presents with rapid dissemination between animals.2 CaHV-1 has a worldwide distribution and is associated with respiratory and reproductive disease.8 Like other Alphaherpesviruses, CaHV-1 establishes latent infections in nerve ganglia and can periodically reactivate the infection.9 An estimated 30–100% of domestic dogs have antibodies to CaHV-1.10
The transmission of respiratory viruses occurs through direct or indirect contact between animals, primarily through contaminated nasal secretions and aerosols.1 CIRD may affect dogs of both genders and ages; puppies under 90 days old are more susceptible, as well as immunosuppressed dogs, animals without a history of vaccination; vaccination failures or maternal immunity may also contribute.11 The disease presents a seasonal pattern with a higher incidence in cold months.12
The diagnosis of CIRD is largely based on the epidemiology, clinical signs and response to therapy. However, an etiologic diagnosis requires the identification of the agent or its products (proteins or nucleic acids).4 Vaccination is largely used to prevent or control respiratory infections in dogs and helps minimize clinical disease; however, current vaccines are not always effective.11
In Brazil, despite the wide distribution of these infections and informal reports by veterinarians, very few reports describe viral respiratory disease in dogs.13, 14, 15, 16, 17, 18 Additionally, there is little information regarding these infections in local environments with high densities and constant animal movement such as dog shelters. The identification of the more common respiratory viruses in dogs in various epidemiological conditions is essential for developing efficient control and prevention measures.
Thus, the objective of this study was to investigate respiratory viral infections in dogs in shelters. For this, three shelters located in Rio Grande do Sul state, Brazil, presenting diverse sanitary and nutrition conditions were included in an attempt to associate the occurrence of viral infections with the conditions observed. The viruses were detected in nasal secretions via polymerase chain reaction (PCR) and focused on the main agents involved in this condition (CDV, CPIV, CAdV-2 and CaHV-1).
Gastrointestinal disorders are frequently reported in companion animal clinics as leading to severe dehydration and death in South America.1, 2 They can have bacterial, parasitic or viral etiologies.3 Viruses associated with enteric illnesses in dogs are an important cause of mortality in nonprotected populations.2 Among these, canine parvovirus (CPV-2) and canine coronavirus (CCoV) are considered the most common viral enteric pathogens in dogs worldwide.4, 5, 6, 7, 8 Canine distemper virus (CDV) is endemic to South America and is frequently associated with enteric disorders.8, 9, 10, 11 Canine adenovirus type 1 (CAdV-1) is commonly linked to hepatitis but was also associated to severe gastroenteritis including vomiting and diarrhea.12 The canine rotavirus (CRV) is an unusual enteric pathogen in dogs but is important due to its zoonotic potential.13, 14
The search for multiple pathogens in fecal samples from dogs can mirror common exposure but can also show interactions between pathogens determining or aggravating disease.15, 16 Moreover, there is a lack of research searching for multiple viral pathogens in dogs, which could uncover the real etiology of canine gastroenteritis. Therefore, the present study aimed to verify the frequency of canine enteric viruses (CPV-2, CCoV, CDV, CAdV1 and CRV) in stool samples from dogs.
A newly described canine circovirus (CanineCV) was identified recently in serum from healthy dogs. Since then, several countries have reported the molecular detection of CanineCV in cases associated with clinical disease, ranging from sudden death of puppies with bloody diarrhea to respiratory syndromes [2–6]. Lesions found include necrotizing vasculitis, lymphoid necrosis, granulomatous inflammation and necrosis of intestinal crypts and Peyer’s patches. Some characteristics of the disease observed in dogs (enteritis, pneumonia, lymphadenitis) were also present in pigs infected with porcine circovirus 2 (PCV-2), which was found to be genetically related.
A number of case-control studies have been published, most of them describing significant association between diarrhea and CanineCV detection [8–11]. The role of this new virus in pathogenesis is however difficult to assess since it is also found in feces from healthy dogs. Furthermore, the first description was done from serum samples from six healthy animals and there have been recent reports of CanineCV in serum samples of dogs from Brazil and China [12, 13]. Additionally, coinfection with other viral pathogens, mainly canine parvovirus (CPV), but also canine distemper virus, canine coronavirus, and canine influenza virus is present in CanineCV positive dogs with clinical symptoms at rates between 50 to 100% [4, 6, 8–11]. Viral coinfection is also a main feature of PCV-2 infection [14, 15].
Circoviruses belong to the family Circoviridae, genus circovirus; they are small, non-enveloped virus with a circular single strand DNA genome of around 2000 bp. The genome contains two main (and opposite) transcription units which encode two ORFs, a replicase associated protein (Rep) and the capsid protein (Cap). CanineCV sequences submitted to Genbank are quite similar differing slightly from those identified in wildlife. Nevertheless, the division of CanineCV into two genotypes (CanineCV-1 and Canine CV-2) based on the cap gene sequence has been proposed very recently.
In this work, we present, to our knowledge, the first report of a complete full-length CanineCV genome sequence from South America.
Canine distemper is a contagious disease with multisystem infection caused by canine distemper virus (CDV), which affects the health of multiple species (1, 2). The disease is characterized by high fever, diarrhea, encephalitis, immunosuppression, and other symptoms. The high mortality and morbidity of dogs and fur animals result in serious economic losses. The emergence of canine distemper has been continuously reported in China (3). Therefore, controlling the spread of CDV still faces enormous challenges. CDV is an enveloped, non-segmented, single-stranded negative RNA virus with a genome size of ~15.7 kb. The genome encodes nucleocapsid protein (N), phosphoprotein (P), matrix protein (M), fusion protein (F), hemagglutinin protein (H), and large protein (L). The CDV envelope consists of two integral glycoproteins, fusion protein (F) and hemagglutinin protein (H) (4). The H gene contains 1,947 nucleotides, encoding 607 amino acids. The size of CDV H protein is ~78 kD. Embedded on the surface of the viral envelope, H protein can effectively induce the body to produce neutralizing antibodies and play an important role in antigenic recognition (5). Recently, many studies reported the application of H protein in vaccines and diagnosis (6, 7). The antigenic epitopes of CDV hemagglutinin protein have not been investigated clearly.
In this study, two B-cell epitopes in H protein were identified by using specific mAbs to react with a series of truncated peptides in ELISA test. The epitope F8 is highly conserved among different isolates of CDV, and the epitope F14-1 contains three mutant residues. The localization of two epitopes on the surface of H protein makes it easy for F8 and F14-1 to induce an immune response during CDV infection. Furthermore, the current work actually provides potential uses for the development of diagnostic methods to detect CDV.