Sequence analysis of divergent canine coronavirus strains present in a UK dog population

Genetic diversity of canine coronavirus identified in dogs in yulin city, southern China

The global outbreak of the novel coronavirus has renewed interest in related viral pathogens, including canine coronavirus (CCoV), which causes severe gastroenteritis, diarrhea, and vomiting in dogs worldwide. While cases of CCoV have been reported in China, specific instances in the Guangxi Zhuang Autonomous Region-a major center for dog breeding and consumption-have not been documented. In this study, we collected spleen tissue samples from dogs in Yulin city and conducted meta-transcriptomic sequencing. Bioinformatics analysis confirmed CCoV presence in these samples. Furthermore, virus screening and phylogenetic analyses identified the circulation of two CCoV genotypes within the dog population, revealing an overall prevalence of 14.2 %, with CCoV-IIb being the predominant genotype. Notably, two significant recombination events were detected among the analyzed strains. These findings provide valuable insights into the presence and genetic diversity of CCoV Yulin's dog populations, enhancing the understanding of its genetic variation and evolution.

A novel linear B cell epitope of the canine coronavirus nucleocapsid protein identified by a monoclonal antibody

The infection of canine coronavirus (CCoV) causes a highly contagious disease in dogs with acute gastroenteritis. The efficient serological diagnostics is critical for controlling the disease caused by CCoV. Nucleocapsid (N) protein of CCoV is an important target for developing serological approaches. However, little is known about the antigenic sites in the N protein of CCoV. In this study, we generated a monoclonal antibody (mAb) against the N protein of CCoV, designated as 13E8, through the fusion of the sp2/0 cells with the spleen cells from a mouse immunized with the purified recombinant GST-N protein. Epitope mapping revealed that mAb 13E8 recognized a novel linear B cell epitope in N protein at 294-314aa (named as EP-13E8) by using a serial of truncated N protein through Western blot and ELISA. Sequence analysis showed that the sequence of EP-13E8 was highly conserved (100 %) among different CCoV strains analyzed, but exhibited a low similarity (31.8-63.6 %) with the responding sequence in other coronaviruses of the same genus such as FCoV, PEDV and HCoV except for TGEV (95.5 % identity). Structural assay suggested that the epitope of EP-13E8 were located in the close proximity on the surface of the N protein. Overall, the mAb 13E8 against N protein generated and its epitope EP-13E8 identified here paid the way for further developing epitope-based serological diagnostics for CCoV.

Molecular Screening and Characterization of Canine Coronavirus Types I and II Strains from Domestic Dogs in Southern Italy, 2019-2021

Canine coronavirus (CCoV) is a common agent of gastroenteritis in dogs, although some variants have been found associated with systemic and often fatal diseases. Distinct genotypes (CCoV-I and CCoV-II) and subgenotypes (CCoV-IIa and CCoV-IIb) are worldwide distributed. In Italy, CCoV infections have been occasionally evaluated, but information about the molecular epidemiology and the genomic features of currently circulating strains is limited. This study reports the detection and molecular characterization of CCoV strains from samples collected from 284 dogs in Italy between 2019 and 2021. CCoV RNA was detected in 39 (13.7%) dogs, as a single viral agent (5 animals, 12.8%) or with other viral pathogens (canine parvovirus types 2a/2b/2c; canine adenovirus type 1; norovirus GIV.2) (34 animals, 87.2%). A total of 48 CCoV strains were detected either alone (CCoV-I: 51.3%, CCoV-IIa: 20.5%) or in copresence (CCoV-I and CCoV-IIa, 23.1%); surprisingly, CCoV-IIb was not identified in this study. Five clusters of CCoV-I were detected, and their spike gene sequences showed the highest nucleotide identities with CCoV-I strains collected from Greece in 2008/2009 and from China in 2021. CCoV-IIa spike gene sequences (three variants) had the highest nucleotide identities with CCoV-IIa strains collected in Greece in 2008/2009 and in Italy in 2009/2011. Given the high CCoV diversity and the variable pathogenicity potential, we underline the need of further surveillance studies to increase our understanding of the epidemiology and evolution of these viruses.

Investigation of circulating infectious agents in experimental Beagle dogs of a production colony and three research facilities in China from June 2021 to May 2022

To understand the epizootiologic characteristics of pathogens and opportunistic infections in one Beagle dog production colony and three research facilities, viruses and mycoplasma were detected in 1777 samples collected from Beagle dogs in China by polymerase chain reaction/reverse transcription polymerase chain reaction, and bacteria were isolated and identified by 16S rRNA sequence analysis. In addition, genotyping of the major circulating viruses was carried out by amplification of gene fragments and homology analysis. Canine coronavirus (CCoV), Escherichia coli, canine parvovirus (CPV), Bordetella bronchiseptica, Clostridium perfringens, Mycoplasma cynos, Klebsiella pneumoniae, Streptococcus canis, canine astrovirus (CaAstV), canine kobuvirus (CaKV), Pseudomonas aeruginosa, Proteus mirabilis, Macrococcus canis, Pasteurella canis, canine bocavirus (CBoV) and canine adenovirus (CAdV) were detected in the samples. Single, double, triple and quadruple infections accounted for 6.6%, 1.4%, 1.2% and 0.96% of samples, respectively. CCoV strains in 81 samples included three genotypes, CCoV-I, CCoV-IIa and CCoV-IIb, by analysis of S gene. The rate of single infection of CCoV-I, CCoV-IIa or CCoV-IIb was 19%, 38% or 7.4% respectively. The double and triple infection rates of CCoV were 32.8% and 2.5% respectively. All CPV strains in 36 samples belonged to CPV-2c. There were three amino acid differences in the Fiber protein of CAdV-positive sample QD2022, compared with the reference strain Toronto A26/61 and the vaccine strain YCA-18. These results suggest that CCoV and CPV are primary infectious agents, and that these two viruses were often identified in mixed infections, or coinfections alongside mycoplasma or other bacteria. These results will provide the basis for improvements in prevention and control of naturally occurring infectious diseases in Beagle dog production colonies and research facilities.

Epidemiology and Molecular Characterizations of Coronavirus from Companion Animals Living in Chengdu, Southwest China

The recent COVID-19 pandemic has once again caught the attention of people on the probable zoonotic transmission from animals to humans, but the role of companion animals in the coronavirus (CoV) epidemiology still remains unknown. The present study was aimed to investigate epidemiology and molecular characterizations of CoVs from companion animals in Chengdu city, Southwest China. 523 clinical samples from 393 animals were collected from one veterinary hospital between 2020 and 2021, and the presence of CoVs was detected by end-point PCR using pan-CoV assay targeting the RdRp gene. Partial and complete S genes were sequenced for further genotyping and genetic diversity analysis. A total of 162 (31.0%, 162/523) samples and 146 (37.2%, 146/393) animals were tested positive for CoVs. The positive rate in rectal swabs was higher than that in eye/nose/mouth swabs and ascitic fluid but was not statistically different between clinically healthy and diseased ones. Genotyping identified twenty-two feline enteric coronavirus (FCoV) I, four canine enteric coronavirus (CECoV) I, fourteen CECoV IIa, and one CECoV IIb, respectively. Eight complete S genes, including one canine respiratory coronavirus (CRCoV) strain, were successfully obtained. FCoV strains (F21071412 and F21061627) were more closely related to CECoV strains than CRCoV, and C21041821-2 showed potential recombination event. In addition, furin cleavage site between S1 and S2 was identified in two strains. The study supplemented epidemiological information and natural gene pool of CoVs from companion animals. Further understanding of other functional units of CoVs is needed, so as to contribute to the prevention and control of emerging infectious diseases.

Prevalence and genetic diversity of canine coronavirus in northeastern China during 2019-2021

Canine coronavirus (CCoV) is associated with diarrhea in dogs, with a high incidence and sometimes even death. However, there is currently limited information about its prevalence and molecular characterization in northeastern China. Therefore, in this study, we examined 325 canine fecal specimens in four provinces in northeastern China from 2019 to 2021. PCR results revealed that 57 out of 325 (17.5%) samples were found to be positive for CCoV, and the positive rate varies obviously with city, season, age and so on. High incidence (65%) of viral co-infection was detected in the diarrhea samples and mixed infection of distinct CCoV genotypes occurs extensively. More importantly, sequence analysis showed that the S gene has a strong mutation. Phylogenetic analysis demonstrated that CCoV-I and CCoV-II strains has different origins. In particular, we found the CCoV-IIa strains of S gene sequenced and the reference strain B906_ZJ_2019 were highly clustered, and the reference strain was a recombinant strain of CCoV-I and CCoV-II. Our findings provide useful orienting clues for evaluating the pathogenic potential of CCoV in canines, and point out more details on characterization in northeastern China. Further work is required to determine the significance and continuous genetic evolution of CCoV.

Study on the Canine Adenovirus Type 1 (CAdV-1) Infection in Domestic Dogs in Southern Italy

Canine adenovirus type 1 (CAdV-1) is the causative agent of a systemic and potentially fatal viral disease of domestic and wild canids. In Italy, CAdV-1 infection has also been occasionally described in dogs, but information on the epidemiology and its genomic features is still limited. A study was conducted on 291 dogs suspected of infectious gastrointestinal disease. Samples collected from dogs in southern Italy between 2017 and 2020 were analyzed. Virological and histopathological assays were carried out. The presence of CAdVs and other canine viral enteropathogens was investigated, and sequence and phylogenetic analyses were performed. CAdV-1 was detected in six (2.1%) dead stray dogs alone or in mixed infections with other viruses. Gross lesions and histopathological findings referred to CAdV infection were observed, also involving the central nervous system tissues. All inoculated samples were successfully isolated. Sequence analysis evidenced divergences with the circulating strains previously described in Italy and a closer relation with older CAdV-1 strains collected from other countries, suggesting a genetic heterogeneity of CAdV-1 in Italy. The evidence of the circulation of CAdV-1 and its genomic features allows us to have more in-depth knowledge of the epidemiology and evolution of the CAdV-1 genomic variants.

Detection and Molecular Characterization of Canine Alphacoronavirus in Free-Roaming Dogs, Bangladesh

Canine coronavirus (CCoV) is widespread among the dog population and causes gastrointestinal disorders, and even fatal cases. As the zoonotic transmission of viruses from animals to humans has become a worldwide concern nowadays, it is necessary to screen free-roaming dogs for their common pathogens due to their frequent interaction with humans. We conducted a cross-sectional study to detect and characterize the known and novel Corona, Filo, Flavi, and Paramyxoviruses in free-roaming dogs in Bangladesh. Between 2009-10 and 2016-17, we collected swab samples from 69 dogs from four districts of Bangladesh, tested using RT-PCR and sequenced. None of the samples were positive for Filo, Flavi, and Paramyxoviruses. Only three samples (4.3%; 95% CI: 0.9-12.2) tested positive for Canine Coronavirus (CCoV). The CCoV strains identified were branched with strains of genotype CCoV-II with distinct distances. They are closely related to CCoVs from the UK, China, and other CoVs isolated from different species, which suggests genetic recombination and interspecies transmission of CCoVs. These findings indicate that CCoV is circulating in dogs of Bangladesh. Hence, we recommend future studies on epidemiology and genetic characterization with full-genome sequencing of emerging coronaviruses in companion animals in Bangladesh.

Molecular survey of parvovirus, astrovirus, coronavirus, and calicivirus in symptomatic dogs

Gastrointestinal disorders caused by enteric viruses are frequently reported in dogs worldwide, with significant mortality rates in unvaccinated individuals. This study reports the identification and molecular characterization of Canine parvovirus (CPV-2), Canine coronavirus (CcoV), Canine astrovirus (AstV), and Canine calicivirus (CcaV) in a panel of dogs showing severe enteric clinical signs sampled in a typical Mediterranean environment (Sardinia, Italy). At least one of these viral species was detected in 92.3% samples. CPV-2 was the most frequently detected virus (87.2%), followed by AsTv (20.5%), CCoV-IIa (18%), and CCoV-I (10.3%). CCoV-IIb and CaCV were not detected in any sample. Single infection was detected in 24 samples (66.7%), mainly related to CPV-2 (91.7%). Coinfections were present in 33.3% samples with constant detection of CPV-2. Canine coronavirus was present only in coinfected animals. The VP2 sequence analysis of CPV-2 positive samples confirmed the presence of all variants, with CPV-2b most frequently detected. Phylogeny based on the CcoV-IIa spike protein (S) gene allowed to identify 2 different clades among Sardinian isolates but failed to distinguish enteric from pantropic viruses. Study on presence and prevalence of enteroviruses in dogs increase our knowledge about the circulation of these pathogens in the Mediterranean area and highlight the need for dedicated routine vaccine prophylaxis. Molecular analyses of enteric viruses are fundamental to avoid failure of vaccines caused by frequent mutations observed in these enteroviruses.

Etiology and genetic evolution of canine coronavirus circulating in five provinces of China, during 2018-2019

As the outbreaks of COVID-19 in worldwide, coronavirus has once again caught the attention of people. Canine coronavirus is widespread among dog population, and sometimes causes even fatal cases. Here, to characterize the prevalence and evolution of current circulating canine coronavirus (CCoV) strains in China, we collected 213 fecal samples from diarrheic pet dogs between 2018 and 2019. Of the 213 samples, we found 51 (23.94%) were positive for CCoV. Co-infection with canine parvovirus (CPV), canine astrovirus (CaAstV), canine kobuvirus (CaKV), Torque teno canis virus (TTCaV) were ubiquitous existed. Mixed infection of different CCoV subtypes exists extensively. Considering the limited sequences data in recent years, we sequenced 7 nearly complete genomes and 10 complete spike gene. Phylogenetic analysis of spike gene revealed a new subtype CCoV-II Variant and CCoV-IIa was the most prevalent subtype currently circulating. Moreover, we identified strain B906_ZJ_2019 shared 93.24% nucleotide identifies with previous strain A76, and both of them clustered with CCoV-II Variant, which were not well clustered with the known subtypes. Recombination analysis of B906_ZJ_2019 indicated that strain B906_ZJ_2019 may a recombinant variant between CCoV-I and CCoV-II, which is consistent with strain A76. Furthermore, amino acid variations widely existed among current CCoV-IIa strains circulating in China and the classic CCoV-IIa strains, in spite of the unknown functions. In a word, we report a useful information as to the etiology and evolution of canine coronavirus in China based on the available sequences, which is urgent for the devise of future effective disease prevention and control strategies.

A fast and simple one-step duplex PCR assay for canine distemper virus (CDV) and canine coronavirus (CCoV) detection

The one-step polymerase chain reaction (one-step PCR) detection assay is an innovative PCR detection method, eliminating nucleic acid extraction steps, in which samples can be directly added to PCR reagents for testing. For simultaneous detection of CDV and CCoV, a sensitive and specific one-step duplex PCR (one-step dPCR) assay was developed with two pairs of primers that were designed based on H and M gene sequences of CDV and CCoV, respectively. The one-step dPCR with optimized detection conditions has high specificity and sensitivity; independent sequencing assays further verified these results.

Molecular characterization of canine parvovirus and canine enteric coronavirus in diarrheic dogs on the island of St. Kitts: First report from the Caribbean region

Although canine parvovirus (CPV) and canine enteric coronavirus (CCoV) are important enteric pathogens of dogs and have been studied extensively in different parts of the world, there are no reports on these viruses from the Caribbean region. During 2015–2016, a total of 104 diarrheic fecal samples were collected from puppies and adult dogs, with or without hemorrhagic gastroenteritis, on the Caribbean island of St. Kitts (KNA). By PCR, 25 (24%, n = 104) samples tested positive for CPV. Based on analysis of the complete deduced VP2 amino acid sequences, 20 of the KNA CPV strains were assigned to new CPV-2a (also designated as CPV-2a-297A). On the other hand, the VP2 genes of the remaining 5 strains were partially characterized, or could not be sequenced. New CPV-2a was the predominant CPV variant in St. Kitts, contrasting the molecular epidemiology of CPV variants reported in most studies from nearby North and South American countries. By RT-PCR, CCoVs were detected in 5 samples (4.8%, n = 104). Based on analysis of partial M-protein gene, the KNA CCoV strains were assigned to CCoV-I genotype, and were closely related to CCoV-I strains from Brazil. To our knowledge, this is the first report on detection and genetic diversity of CPV and CCoV in dogs from the Caribbean region, and underscores the importance of similar studies in the other Caribbean islands.

Genetic and antigenic characterization of recombinant nucleocapsid proteins derived from canine coronavirus and canine respiratory coronavirus in China

To characterize the antigenicity of nucleocapsid proteins (NP) derived from canine coronavirus (CCoV) and canine respiratory coronavirus (CRCoV) in China, the N genes of CCoV (CCoV-BJ70) and CRCoV (CRCoV-BJ202) were cloned from swabs obtained from diseased pet dogs in Beijing and then sequenced. The recombinant NPs (rNPs) were expressed in Escherichia coli and purified by nickel-affinity column and size exclusion chromatography. Sequencing data indicated that the N genes of CCoV-BJ70 and CRCoV-BJ202 belonging to two distinctly different groups were relatively conserved within each subgroup. Sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) results showed that rNPs of CCoV and CRCoV were expressed efficiently and isolated with a final purity of over 95%. Western blot analysis revealed the rNP from CRCoV could cross-react with mice antisera against human coronavirus (HCoV-229E, NL63, OC43, HKU1), while rNP of CCoV had cross-reactivity with only anti-sera against viruses belonging to the same group (HCoV-229E and NL63). In summary, CCoV and CRCoV rNPs were successfully expressed in E. coli and showed antigenic cross-reactivity with antisera raised against human coronaviruses. These findings indicate that further serologic studies on coronavirus infections at the animal-human interface are needed.

Co-Circulation of Canine Coronavirus I and IIa/b with High Prevalence and Genetic Diversity in Heilongjiang Province, Northeast China

To trace the evolution of canine coronavirus (CCoV), 201 stool samples from diarrheic dogs in northeast China were subjected to reverse transcription-polymerase chain reactions (RT-PCRs) targeting the partial M and S genes of CCoV, followed by an epidemiological analysis. M gene RT-PCRs showed that 28.36% (57/201) of the samples were positive for CCoV; of the 57 positive samples, CCoV-I and CCoV-II accounted for 15.79% (9/57) and 84.21% (48/57), respectively. A sequence comparison of the partial M gene revealed nucleotide homologies of 88.4%-100% among the 57 CCoV strains, and 88.7%-96.2% identity between the 57 CCoV strains and the Chinese reference strain HF3. The CCoV-I and CCoV-II strains exhibited genetic diversity when compared with reference strains from China and other countries. The 57 CCoV strains exhibited high co-infection rates with canine kobuvirus (CaKV) (33.33%) and canine parvovirus-2 (CPV-2) (31.58%). The CCoV prevalence in diarrheic dogs differed significantly with immunization status, regions, seasons, and ages. Moreover, 28 S genes were amplified from the 57 CCoV-positive samples, including 26 CCoV-IIa strains, one CCoV-IIb strain, and one CCoV-I strain. A sequence comparison of the partial S gene revealed 86.3%-100% nucleotide identity among the 26 CCoV-IIa strains, and 89.6%-92.2% identity between the 26 CCoV-IIa strains and the Chinese reference strain V1. The 26 CCoV-IIa strains showed genetic diversity when compared with reference strains from China and other countries. Our data provide evidence that CCoV-I, CCoV-IIa, and CCoV-IIb strains co-circulate in the diarrhoetic dogs in northeast China, high co-infection rates with CaKV and CPV-2 were observed, and the CCoV-II strains exhibited high prevalence and genetic diversity.

Molecular Characterization of Canine Coronavirus

Canine coronavirus (CCoV) is usually the cause of mild gastroenteritis in dogs and is known to have spread worldwide. In the last decade, as a consequence of the extraordinary large RNA genome, novel recombinant variants of CCoV have been found that are closely related to feline and porcine strains. Moreover highly virulent pantropic CCoV strains were recently identified in dogs. The molecular characterization of the CCoV circulating in canine population is essential for understanding viral evolution.

Prevalence of canine coronavirus (CCoV) in dog in Japan: detection of CCoV RNA and retrospective serological analysis

We collected rectal swabs from dogs in Japan during 2011 to 2014, and canine coronavirus (CCoV) nucleocapsid gene was detected by RT-PCR. The relationship between CCoV infection and the manifestation of diarrhea symptoms was investigated, and a correlation was noted (df=1, χ²=8.90, P<0.005). The types of CCoV detected in samples from CCoV-infected dogs were CCoV-I in 88.9% and CCoV-II in 7.4%, respectively. We retrospectively investigated the seroprevalence of CCoV-I in dogs in Japan during 1998 to 2006. The sera were tested with a neutralizing antibody test. In the absence of CCoV-I laboratory strain, we used feline coronavirus (FCoV)-I that shares high sequence homology in the S protein with CCoV-I. 77.7% of the sera were positive for neutralizing anti-FCoV-I antibodies.

Detection of canine astrovirus in dogs with diarrhea in Japan

Canine astrovirus (CAstV) is the causative agent of gastroenteritis in dogs. We collected rectal swabs from dogs with or without diarrhea symptoms in Japan and examined the feces for the presence of CAstV by RT-PCR with primers based on a conserved region of the ORF1b gene. The ORF1b gene of CAstV was not detected in the 42 dogs without clinical illness but was present in three pups out of the 31 dogs with diarrhea symptoms. Based on the full-length capsid protein, the CAstV KU-D4-12 strain that we detected in this study shared high homology with the novel virulent CAstV VM-2011 strain.

New and Emerging Pathogens in Canine Infectious Respiratory Disease

Canine infectious respiratory disease is a common, worldwide disease syndrome of multifactorial etiology. This review presents a summary of 6 viruses (canine respiratory coronavirus, canine pneumovirus, canine influenza virus, pantropic canine coronavirus, canine bocavirus, and canine hepacivirus) and 2 bacteria ( Streptococcus zooepidemicus and Mycoplasma cynos) that have been associated with respiratory disease in dogs. For some pathogens a causal role is clear, whereas for others, ongoing research aims to uncover their pathogenesis and contribution to this complex syndrome. Etiology, clinical disease, pathogenesis, and epidemiology are described for each pathogen, with an emphasis on recent discoveries or novel findings.

Molecular characterization of canine coronavirus strains circulating in Brazil

To characterize canine coronavirus (CCoV) circulating in diarrheic puppies in Brazil, 250 fecal samples collected between 2006 and 2012 were tested. By using RT-PCR to partially amplify the M gene, CCoV RNA was detected in 30 samples. Sequence analysis of the M protein grouped eight strains with CCoV-I and another 19 with CCoV-II prototypes. To genotype/subtype the CCoV strains and assess the occurrence of single or multiple CCoV infections, RT-PCR of the S gene was performed, and 25/30 CCoV-positive strains amplified with one or two primer pairs. For 17/25 samples, single infections were detected as follows: six CCoV-I, nine CCoV-IIa and two CCoV-IIb. Eight samples were positive for more than one genotype/subtype as follows: seven CCoV-I/IIa and one CCoV-I/IIb. Sequence analysis revealed that the CCoV-I and IIa strains shared high genetic similarity to each other and to the prototypes. The Brazilian strains of CCoV-IIb displayed an aminoacid insertion that was also described in CCoV-IIb-UCD-1 and TGEV strains. Among the 25 CCoV-positive puppies, five had a fatal outcome, all but one of which were cases of mixed infection. The current study is the first reported molecular characterization of CCoV-I, IIa and IIb strains in Brazil.

Canine coronavirus, Greece. Molecular analysis and genetic diversity characterization

Canine coronavirus (CCoV) is an etiologic agent of diarrhea in dogs and is known to have spread worldwide. Mild disease or asymptomatic carriage are probably in many cases common outcomes of infection. To date, two different genotypes of CCoV are known, CCoV type I (CCoV-I) and CCoV type II (CCoV-II). CCoV type II is divided in two subtypes, CCoV-IIa (classical strains) and CCoV-IIb, with CCoV-IIb emerging as a result of a putative recombination between CCoV-IIa and transmissible gastroenteritis virus (TGEV). The aim of the present study was to investigate the presence of CCoV in Greece and to genetically analyze the circulating strains. Between December 2007 and December 2009, 206 fecal samples were collected from dogs with diarrhea from kennels, pet shops and veterinary clinics of different country regions. RT-PCR and real time RT-PCR assays were used for CCoV detection and characterization. CCoV was identified in 65.1% of the dogs presenting diarrhea, being more frequently detected in animals younger than 3 months old and in animals housed in groups. In 47% of the positive samples more than one CCoV genotype/subtype were detected, with triple CCoV-I/CCoV-IIa/CCoV-IIb infections being identified for the first time. Molecular and phylogenetic analysis revealed that CCoV-I Greek strains share low genetic relatedness to each other and to the prototype CCoV-I strains in the 5’ end of the S gene. Moreover, a divergent CCoV-IIa strain was identified. The circulation of highly variable CCoV-I and CCoV-IIb emerging strains, as well as the detection of the divergent strain, raise concerns on the importance of these new strains as primary pathogens of diarrhoeic syndromes diagnosed in dogs.

European surveillance for pantropic canine coronavirus

Highly virulent pantropic canine coronavirus (CCoV) strains belonging to subtype IIa were recently identified in dogs. To assess the distribution of such strains in Europe, tissue samples were collected from 354 dogs that had died after displaying systemic disease in France (n = 92), Hungary (n = 75), Italy (n = 69), Greece (n = 87), The Netherlands (n = 27), Belgium (n = 4), and Bulgaria (n = 1). A total of 124 animals tested positive for CCoV, with 33 of them displaying the virus in extraintestinal tissues. Twenty-four CCoV strains (19.35% of the CCoV-positive dogs) detected in internal organs were characterized as subtype IIa and consequently assumed to be pantropic CCoVs. Sequence and phylogenetic analyses of the 5' end of the spike protein gene showed that pantropic CCoV strains are closely related to each other, with the exception of two divergent French viruses that clustered with enteric strains.

Characterization of a recombinant canine coronavirus with a distinct receptor-binding (S1) domain

Canine alphacoronaviruses (CCoV) exist in two serotypes, type I and II, both of which can cause severe gastroenteritis. Here, we characterize a canine alphacoronavirus, designated CCoV-A76, first isolated in 1976. Serological studies show that CCoV-A76 is distinct from other CCoVs, such as the prototype CCoV-1-71. Efficient replication of CCoV-A76 is restricted to canine cell lines, in contrast to the prototypical type II strain CCoV-1-71 that more efficiently replicates in feline cells. CCoV-A76 can use canine aminopeptidase N (cAPN) receptor for infection of cells, but was unable to use feline APN (fAPN). In contrast, CCoV-1-71 can utilize both. Genomic analysis shows that CCoV-A76 possesses a distinct spike, which is the result of a recombination between type I and type II CCoV, that occurred between the N- and C-terminal domains (NTD and C-domain) of the S1 subunit. These data suggest that CCoV-A76 represents a recombinant coronavirus form, with distinct host cell tropism.

Cross sectional and longitudinal surveys of canine enteric coronavirus infection in kennelled dogs: a molecular marker for biosecurity

Previous studies have suggested that kennelled dogs are more likely to test positive for CECoV than household pets. Here we describe both cross sectional and longitudinal studies in two rescue kennels and two boarding kennels, together with molecular diagnostics, to provide a new insight into the epidemiology of CECoV. Prevalence of CECoV in the cross sectional studies tended to be higher in the rescue kennels (13.8% and 33.3%) than the boarding kennels (5.3% and 13.5%). In each kennel, type I CECoV was more prevalent than type 2 CECoV. The mean quantity of type I detected was equivalent to 6.3 × 10⁸ gc/gm (range = 5 × 10⁶, 8.5 × 10¹¹), compared to 1.3 × 10⁸ gc/gm (range = 3 × 10⁶, 2.4 × 10¹⁰) for type II. In one rescue shelter where dogs were followed longitudinally, infection was significantly associated with accommodation block as well as the length of stay (increased risk of CECoV per week in residence of ×1.9). Of those animals sampled on two or more occasions, none tested positive on arrival, and 54.5% later shed CECoV, suggesting that infection may have been acquired within the kennel. Shedding patterns and sequence analysis suggested both types I and II CECoV were maintained in this population by a combination of introductions into the shelter and within-shelter transmission. The findings suggest that some kennel environments may be important in maintaining CECoV infection in the population. We also propose that the diversity of viruses like CECoV in these populations may provide a novel surrogate marker for the success of biosecurity.

Feline and canine coronaviruses: common genetic and pathobiological features

A new human coronavirus responsible for severe acute respiratory syndrome (SARS) was identified in 2003, which raised concern about coronaviruses as agents of serious infectious disease. Nevertheless, coronaviruses have been known for about 50 years to be major agents of respiratory, enteric, or systemic infections of domestic and companion animals. Feline and canine coronaviruses are widespread among dog and cat populations, sometimes leading to the fatal diseases known as feline infectious peritonitis (FIP) and pantropic canine coronavirus infection in cats and dogs, respectively. In this paper, different aspects of the genetics, host cell tropism, and pathogenesis of the feline and canine coronaviruses (FCoV and CCoV) will be discussed, with a view to illustrating how study of FCoVs and CCoVs can improve our general understanding of the pathobiology of coronaviruses.

Isolation, tissue distribution and molecular characterization of two recombinant canine coronavirus strains

Canine coronavirus (CCoV) is an enveloped RNA virus, responsible for gastrointestinal infection in dogs. To date, two different CCoV genotypes have been recognized, CCoV type I and CCoV type II. Recently, CCoV type II strains of potential recombinant origin with transmissible gastroenteritis virus (TGEV) were detected and characterized as a new subtype (CCoV-IIb) of canine coronavirus, in order to be differentiated from the "classical" CCoV type II strains (CCoV-IIa). In the present study, two CCoV-IIb strains were detected in the faeces and internal organs of two puppies, which died after presenting gastrointestinal symptoms. Mixed infection of both subtypes (CCoV-IIa/IIb) was detected in the faeces, while only CCoV-IIb was detected in the organs. Puppies were also infected by canine parvovirus type 2 (CPV-2). Both CCoV-IIb strains were isolated on cell cultures and subjected to sequence analysis and phylogeny. By means of RT-PCR and real time RT-PCR assays, tissue distribution and quantitation of viral loads took place. These cases represent the first description of tissue distribution and quantitation of CCoV-IIb strains, detected in the organs. The detection of CCoV-IIa strains, which is restricted to the faeces, suggests that CCoV-IIb strains may have an advantage in disseminating throughout a dog with CPV-2 coinfection, in contrast to common enteric CCoV-IIa strains.

Immunogenicity and protective efficacy in dogs of an MF59™-adjuvanted vaccine against recombinant canine/porcine coronavirus

Recently, canine coronavirus (CCoV) strains with putative recombinant origin with porcine transmissible gastroenteritis virus (TGEV) were shown to be widespread in Europe. In this study, a killed vaccine against TGEV-like CCoV strains, included in the new subtype CCoV-IIb, was developed through inactivation with betapropiolactone and emulsification with MF59™ adjuvant. Safety, immunogenicity and efficacy of the developed vaccine were evaluated in vivo. Five 10-week-old beagle pups were administered (three weeks apart) two vaccine doses, whereas two animals served as unvaccinated controls. The vaccine was shown to be safe as no local neither systemic reactions were observed after first and second dose administration. Serum antibodies against CCoV were detected in vaccinates starting from study day 14 (by enzyme-linked immunosorbent assay) or 28 (by virus neutralisation test). Subsequent challenge with virulent CCoV-IIb resulted in the development of mild gastroenteric disease in control pups, whereas vaccinates did not display clinical signs. Faecal shedding of the challenge virus occurred in both treatment groups, but vaccinated dogs were found to shed very low viral titres in comparison to controls. The developed vaccine may help control the CCoV-IIb-induced disease (and active virus circulation) in environments, such as kennels and shelters, where the pathogenic potential of this virus is greater as a consequence of predisposing factors and concurrent infections.

Detection and genetic characterization of canine parvoviruses and coronaviruses in southern Ireland

Canine parvovirus (CPV) and canine coronavirus (CCoV) are considered the main pathogens responsible for acute gastroenteritis in dogs. From a collection of 250 samples, seven CPV strains and three CCoV strains were identified in symptomatic Irish dogs. Samples were screened for the viruses using polymerase chain reaction (PCR) and typed via DNA sequence analysis. Three CPV strains were characterized as CPV-2a, while four others were characterized as CPV-2b. To date, CPV-2c remains unreported in Ireland. Two CCoV strains were characterized as CCoV-II and one as CCoV-I. In the case of one sample, PH4/09/Ire, a mixed infection with CPV and CCoV was detected.

Detection and genotyping of canine coronavirus RNA in diarrheic dogs in Japan

To clarify the prevalence of canine coronavirus (CCoV) infection in Japan, faecal samples from 109 dogs with diarrhoea were examined for CCoV RNA together with canine parvovirus type 2 (CPV-2) DNA. The detection rates of CCoV and CPV-2 for dogs aged less than 1 year were 66.3% and 43.8%, while those for dogs aged 1 year or older were 6.9% and 10.3%, respectively, which were significantly different (p < 0.0001 and p = 0.0003, respectively), indicating not CPV-2 but CCoV is an important diarrhoea-causing organism in juvenile dogs. Among the CCoV-positive dogs, 65.5% and 72.7% showed to be positive for CCoV types I and II, respectively, and simultaneous detection rate of both types was high at 40.0%. Furthermore, transmissible gastroenteritis virus (TGEV)-like CCoV RNA was detected from 8 dogs. These findings indicate that CCoV type I and TGEV-like CCoV are already circulating in Japan, though no reports have been presented to date.

Recombinant canine coronaviruses in dogs, Europe

Subtype IIb originates from recombination with porcine transmissible gastroenteritis virus.

Coronaviruses of potential recombinant origin with porcine transmissible gastroenteritis virus (TGEV), referred to as a new subtype (IIb) of canine coronavirus (CCoV), were recently identified in dogs in Europe. To assess the distribution of the TGEV-like CCoV subtype, during 2001–2008 we tested fecal samples from dogs with gastroenteritis. Of 1,172 samples, 493 (42.06%) were positive for CCoV. CCoV-II was found in 218 samples, and CCoV-I and CCoV-II genotypes were found in 182. Approximately 20% of the samples with CCoV-II had the TGEV-like subtype; detection rates varied according to geographic origin. The highest and lowest rates of prevalence for CCoV-II infection were found in samples from Hungary and Greece (96.87% and 3.45%, respectively). Sequence and phylogenetic analyses showed that the CCoV-IIb strains were related to prototype TGEV-like strains in the 5′ and the 3′ ends of the spike protein gene.