Molecular characterization of canine parvovirus strains in Argentina: Detection of the pathogenic variant CPV2c in vaccinated dogs

Comparative genomics of canine parvovirus in South America: Diversification patterns in local populations

Canine parvovirus (CPV) is a significant pathogen in domestic dogs worldwide, causing a severe and often fatal disease. CPV comprises three antigenic variants (2a, 2b, and 2c) distributed unevenly among several phylogenetic groups. The present study compared genetic variability and evolutionary patterns in South American CPV populations. We collected samples from puppies suspected of CPV infection in the neighboring Argentina and Uruguay. Antigenic variants were preliminarily characterized using PCR-RFLP and partial vp2 sequencing. Samples collected in Argentina during 2008-2018 were mainly of the 2c variant. In the Uruguayan strains (2012-2019), the 2a variant wholly replaced the 2c from 2014. Full-length coding genome and vp2 sequences were compared with global strains. The 2c and 2a strains fell by phylogenetic analysis into two phylogroups (Europe I and Asia I). The 2c strains from Argentina and Uruguay clustered in the Europe I group, with strains from America, Europe, Asia, and Oceania. Europe I is widely distributed in South America in the dog population and is also being detected in the wildlife population. The 2a strains from Uruguay formed the distinct Asia I group with strains from Asia, Africa, America, and Oceania. This Asia I group is increasing its distribution in South America and worldwide. Our research reveals high genetic variability in adjacent synchronic samples and different evolutionary patterns in South American CPV. We also highlight the importance of ancestral migrations and local diversification in the evolution of global CPV strains.

Detection and genetic characterization of circulating canine parvovirus from stray dogs in Shanghai, China

Canine parvovirus (CPV) is the main cause of viral diarrhea in dogs. CPV became a global disease in 1978 and was endemic all over the world. CPV-2 was the first strain to be identified, but with genetic mutations, new genotypes such as CPV-2a/2b/2c/new-2a/new-2b have emerged. In this study, 128 fecal samples of stray dogs suspected of CPV-2 infection were collected from January to March 2021 in Shanghai, China. All samples were screened by PCR and further analyzed by VP2 gene. The positive rate of CPV-2 was 9.4% (12/128), of which 6 CPV-2 isolates were successfully isolated. Phylogenetic tree analysis showed that 4 isolates were CPV-2c genotype and 2 were new-CPV-2b genotype. VP-2 is a key protein that determines the antigenic properties, host range and receptor binding of cpv-2. The results of VP2 amino acid sequence analysis in this study showed that the CPV-2c isolated strain was the same as the previous strains reported in China, including F267Y, Y324I, Q370R and A5G mutations in addition to the typical N426E mutations. Similarly, in addition to the conventional N426D, S297A, F267Y and Y324I mutations, the new CPV-2b isolate also had a new mutation of T440A. This study further confirmed the prevalence of CPV-2c and new-CPV-2b in Shanghai, and also found a new mutation site of new-CPV-2c, which provided a theoretical basis for further enriching the epidemiological data of CPV-2 in Shanghai, as well as the development of vaccines and the prevention and control of the disease.

Old and Novel Enteric Parvoviruses of Dogs

Parvovirus infections have been well known for around 100 years in domestic carnivores. However, the use of molecular assays and metagenomic approaches for virus discovery and characterization has led to the detection of novel parvovirus species and/or variants in dogs. Although some evidence suggests that these emerging canine parvoviruses may act as primary causative agents or as synergistic pathogens in the diseases of domestic carnivores, several aspects regarding epidemiology and virus-host interaction remain to be elucidated.

Molecular Characterization of Canine Parvovirus Variants CPV-2a and CPV-2c, Associated with Vaccinated Dogs at Libreville, Gabon

The first detection of canine parvovirus type-2 (CPV-2) was in the early 1970s, when it was known to cause severe gastroenteritis in dogs. However, it has evolved over the years into CPV-2a within 2 years, into CPV-2b after 14 years, into CPV-2c after 16 years and more recently CPV-2a-, 2b- and 2c-like variants reported in 2019, with a global distribution. Reports on the molecular epidemiology of this virus are missing in most African countries. The report of clinical cases among vaccinated dogs in Libreville in Gabon triggered the execution of this study. The objective of this study was to characterize circulating variants from dogs showing clinical signs suggestive of CPV that were examined by a veterinarian. A total of eight (8) fecal swab samples were collected, and all had positive PCR results. Sequencing, Blast analysis and assembly of two whole genomes and eight partial VP2 sequences were performed, and the sequences submitted to GenBank. Genetic characterization revealed the presence of CPV-2a and CPV-2c variants with predominance of the former. Phylogenetically, the Gabonese CPVs formed distinct groups similar to Zambian CPV-2c and Australian CPV-2a sequences. The antigenic variants CPV-2a and CPV-2c have not yet been reported in Central Africa. However, these CPV-2 variants circulate in young, vaccinated dogs in Gabon. These results suggest additional epidemiological and genomic studies are required in order to evaluate the occurrence of different CPV variants in Gabon and effectiveness of the commercial vaccines used against protoparvovirus in the country.

Predominance and first complete genomic characterization of canine parvovirus 2b in Turkey

Viral enteritis is a significant threat to domestic dogs. The two primary pathogens that cause viral enteritis in dogs are canine coronavirus (CCoV) and canine parvovirus (CPV). In this study, we investigated the occurrence of CPV-2, CCoV, and canine circovirus coinfection by characterizing circulating subtypes of CPV-2 in faecal samples from symptomatic dogs admitted to veterinary clinics located in Ankara, Elazığ, Kayseri, and Kocaeli provinces of Turkey, between 2019 and 2022. Virus detection by PCR and RT-PCR revealed that CPV-2 was present in 48 (77.4%) samples, and no other agents were detected. Based on the occurrence of the codon GAT at positions 1276 to 1278 (coding for aspartate at residue 426) of VP2, all CPV-2 isolates were confirmed to be of the CPV-2b subtype. The complete genome sequences of two CPV-2b isolates showed a high degree of similarity to and phylogenetic clustering with Australian and East Asian strains/isolates. The predominant CPV strain circulating in the three different regions of Turkey was found to be a CPV-2b strain containing the amino acid substitutions at Y324I and T440A, which commonly contribute to immune escape. This is the first report of complete genomic analysis of CPV-2 isolates circulating in symptomatic domestic dogs in Turkey. The evolution of CPV-2 has raised questions about the efficacy of current vaccination regimes and highlights the importance of monitoring the emergence and spread of new CPV-2 variants.

Emerging Parvoviruses in Domestic Cats

Parvovirus infections in cats have been well known for around 100 years. Recently, the use of molecular assays and metagenomic approaches for virus discovery and characterization has led to the detection of novel parvovirus lineages and/or species infecting the feline host. However, the involvement of emerging parvoviruses in the onset of gastroenteritis or other feline diseases is still uncertain.

Epidemiology and molecular characterization of Carnivore protoparvovirus-1 infection in the wild felid Leopardus guigna in Chile

Landscape anthropization has been identified as one of the main drivers of pathogen emergence worldwide, facilitating pathogen spillover between domestic species and wildlife. The present study investigated Carnivore protoparvovirus-1 infection using molecular methods in 98 free-ranging wild guignas (Leopardus guigna) and 262 co-occurring owned, free-roaming rural domestic cats. We also assessed landscape anthropization variables as potential drivers of infection. Protoparvovirus DNA was detected in guignas across their entire distribution range, with observed prevalence of 13.3% (real-time PCR) and 9% (conventional PCR) in guignas, and 6.1% (conventional PCR) in cats. Prevalence in guigna did not vary depending on age, sex, study area or landscape variables. Prevalence was higher in juvenile cats (16.7%) than in adults (4.4%). Molecular characterization of the virus by amplification and sequencing of almost the entire vp2 gene (1,746 bp) from one guigna and five domestic cats was achieved, showing genetic similarities to canine parvovirus 2c (CPV-2c) (one guigna and one cat), feline panleukopenia virus (FPV) (one cat), CPV-2 (no subtype identified) (two cats), CPV-2a (one cat). The CVP-2c-like sequence found in a guigna clustered together with domestic cat and dog CPV-2c sequences from South America, suggesting possible spillover from a domestic to a wild species as the origin of infection in guigna. No clinical signs of disease were found in PCR-positive animals except for a CPV-2c-infected guigna, which had haemorrhagic diarrhoea and died a few days after arrival at a wildlife rescue centre. Our findings reveal widespread presence of Carnivore protoparvovirus-1 across the guigna distribution in Chile and suggest that virus transmission potentially occurs from domestic to wild carnivores, causing severe disease and death in susceptible wild guignas.

Diagnostic Challenges in Canine Parvovirus 2c in Vaccine Failure Cases

In this study, three different diagnostic tests for parvovirus were compared with vaccination status and parvovirus genotype in suspected canine parvovirus cases. Faecal samples from vaccinated (N17) and unvaccinated or unknown vaccination status (N41) dogs that had clinical signs of parvovirus infection were tested using three different assays of antigen tests, conventional and quantitative PCR tests. The genotype of each sample was determined by sequencing. In addition to the suspected parvovirus samples, 21 faecal samples from apparently healthy dogs were tested in three diagnostic tests to evaluate the sensitivity and specificity of the tests. The antigen test was positive in 41.2% of vaccinated dogs and 73.2% of unvaccinated diseased dogs. Conventional PCR and qPCR were positive for canine parvovirus (CPV) in 82.4% of vaccinated dogs and 92.7% of unvaccinated dogs. CPV type-2c (CPV-2c) was detected in 82.75% of dogs (12 vaccinated and 36 unvaccinated dogs), CPV-2b was detected in 5.17% dogs (one vaccinated and two unvaccinated) and CPV-2a in 1.72% vaccinated dog. Mean Ct values in qPCR for vaccinated dogs were higher than the unvaccinated dogs (p = 0.049), suggesting that vaccinated dogs shed less virus, even in clinical forms of CPV. CPV-2c was the dominant subtype infecting dogs in both vaccinated and unvaccinated cases. Faecal antigen testing failed to identify a substantial proportion of CPV-2c infected dogs, likely due to low sensitivity. The faecal samples from apparently healthy dogs (n = 21) showed negative results in all three tests. Negative CPV faecal antigen results should be viewed with caution until they are confirmed by molecular methods.

Canine parvovirus vaccination and immunisation failures: Are we far from disease eradication?

Despite extensive vaccination, canine parvovirus (CPV) remains a leading infectious cause of canine mortality, especially among juveniles. This review provides an update on CPV vaccine types and vaccination protocols. The design of CPV prevention strategies and vaccination programs with a goal of herd immunity has been hampered by deficiencies of studies that model companion animal viral infections and inform an understanding of the basic reproduction number. However, the most important issue in eradication of CPV disease is represented by immunisation failures including: i) the presence of interfering titres of maternally-derived antibodies; ii) the presence of non-responders; and iii) possible reversion to virulence. In contrast, the role of the CPV variants in immunisation failures is widely debated. Taking into account the reduced circulation of canine distemper virus and canine adenovirus type 1 in countries where extensive vaccination is carried out, more effort should be made to aim for CPV eradication, including antibody testing to determine the optimal time for vaccinations of pups and adults and homogeneous vaccine coverage of dog population.

Risk, prognosis and causality of parvo viral enteritis in dogs in Sri Lanka

We studied the causal variation, prognosis and risk factors of parvo viral enteritis using both molecular and statistical analysis. A multivariate factor analysis was performed to see the effect of the breed, age, vaccination status and the leukocyte counts on disease severity and survival. Twenty PCR amplicons (partial VP2 gene) from vaccinated dogs were sequenced to identify the variants. A total of 109 samples were positive for parvo viral DNA, 71 of which were from dogs who have received at least one dose of CPV-2 vaccine. Over 90% were leukopenic on 2^nd and 3^rd day of diarrhoea. Age < 6 months was negatively correlated with leukocyte count and the leukocyte count was negatively correlated with survival. Dobermans and Labradors showed significant negative correlation with survival. All variants of parvovirus affected dogs with the 2c being the predominant (2c = 12, 2a = 7, 2b = 1). All 20 strains harboured three additional amino acid substitutions (i.e. Phe267Tyr, Ser297Ala and Tyr324Ile) and warrant further studies on potential changes of the antigenicity of the virus.

Molecular and restriction fragment length polymorphism analysis of canine parvovirus 2 (CPV-2) in dogs in southeast Anatolia, Turkey

Canine parvovirus-2 (CPV-2) is the aetiological agent of an infectious viral disease of dogs, characterised by diarrhoea and vomiting. Mutations of the CPV-2 genome have generated new variants circulating worldwide. This article reports the molecular analysis of CPV-2 variants collected in the dog population in southeast Anatolia, Turkey. Twenty blood samples previously taken for the laboratory diagnosis of dogs with suspected parvovirus were screened for CPV-2 by polymerase chain reaction (PCR). Of the 20 samples, 18 tested positive for CPV-2. Partial VP2 gene sequencing and restriction fragment length polymorphism (RFLP) analysis revealed CPV-2a (n = 1), CPV-2b (n = 16) and CPV-2c (n = 1) variants. Phylogenetic analysis based on the partial length VP2 gene showed that CPV-2b (n = 15) variants showed sequences clustering separately in the phylogenetic tree. The CPV-2c sample was phylogenetically related to Chinese strains and Indonesia strain, whereas the CPV-2a sample was phylogenetically related to the Portuguese strain. These results, which are the first to demonstrate the presence of CPV-2c in the dog population of southeast Anatolia, Turkey, indicate that CPV-2a/2b/2c variants co-exist in Turkey’s dog population.

Diagnostics and genotyping of Canine parvovirus type 2 (CPV-2) from disease cases in south-eastern Poland

Canine parvovirus type 2 is one of the most common causes of death among puppies. Despite preventive vaccination, the disease continues to be diagnosed. The aim of the study was to provide a molecular characterization of CPV-2 isolates found in southeastern Poland. Genetic CPV-2 material was isolated from the blood (n=10) and feces (n=50) of infected dogs. The presence of CPV-2 was confirmed by amplification of sequences coding both VP1 and VP2 protein. The products of the PCR reaction with primers amplifying VP2 protein were sequenced and used for genotyping. Bioinformatics analysis of the sequenced PCR product was performed to determine the phylogenetic relationships with variants recorded in the public databases. Based on the analysis of polymorphism in the nucleotide sequence 7 nucleotide variants were detected and assigned into four amino acid groups. Representatives of three groups contained asparagine at amino acid position 426 of the VP2 protein, which is characteristic of CPV-2a. The variant from the fourth group belonged to type CPV-2b. CPV-2a is the dominant antigenic type of CPV-2 in Poland. The pathogen’s high degree of polymorphism is manifested not only by the presence of numerous variants within the type, but also by the presence of representatives of type CPV-2b. Further studies of the molecular epidemiology of CPV-2 are necessary to optimize the effectiveness of preventive measures.

Origin and genetic diversity of canine parvovirus 2c circulating in Mexico

Canine parvovirus type 2 (CPV-2) emerged in the late 1970 s as a pathogen that is capable of causing high rates of morbidity and mortality in dogs. Currently, three genetic variants circulate worldwide (CPV 2a, 2b, and 2c); however, epidemiological studies have not been conducted in all countries to identify its variants. The objectives of this work were to determine which genotypes of CPV-2 circulate in Mexico and to identify the genetic relationships between CPV-2 sequences from Mexico and those from other parts of the world. Samples from five geographical regions of Mexico were analysed by PCR for identification of CPV-2. Here, 1638 bp of the VP2 gene were amplified and sequenced from 50 CPV-2-positive samples, and a phylogenetic network was assembled using these 50 sequences and 150 others obtained from GenBank, representing different countries around the world. The network showed that the most common genotype circulating in the geographic zones of Mexico was CPV-2c. In the network, the 50 samples were organised into two clusters: cluster I, derived from a group of samples of European origin, which belong to genotype 2c, and cluster II, derived from samples belonging to genotype 2b from the USA. Our data suggest that the CPV-2 strains circulating in Mexico originated from two possible virus introduction events. In addition, high genetic diversity was observed among the CPV-2c-derived sequences, which correspond exclusively to the presence of Mexican CPV-2c haplotypes.

Characterization of dog serum virome from Northeastern Brazil

Domestic dogs share habitats with human, a fact that makes them a potential source of zoonotic viruses. Moreover, knowledge regarding possible bloodborne pathogens is important due to the increasing application of blood transfusion in dogs. In the present study, we evaluated the serum virome of 520 dogs using throughput sequencing (HTS). The serum samples were pooled and sequenced using an Illumina MiSeq platform. Our unbiased method identified prevalent canine pathogens as canine protoparvovirus 1 (canine parvovirus 2), undersearched agents as canine bocaparvovirus 1 (minute virus of canines) and canine circovirus, circular viruses closely related to viruses recently found in human samples, and new parvovirus and anelloviruses. The dog virome described in the present work furthers the knowledge concerning the viral population in domestic animals. The present data includes information regarding viral agents that are potentially transmitted through blood transfusion among dogs.

Inter- and intracontinental migrations and local differentiation have shaped the contemporary epidemiological landscape of canine parvovirus in South America

Canine parvovirus (CPV) is a fast-evolving single-stranded DNA virus that causes one of the most significant infectious diseases of dogs. Although the virus dispersed over long distances in the past, current populations are considered to be spatially confined and with only a few instances of migration between specific localities. It is unclear whether these dynamics occur in South America where global studies have not been performed. The aim of this study is to analyze the patterns of genetic variability in South American CPV populations and explore their evolutionary relationships with global strains. Genomic sequences of sixty-three strains from South America and Europe were generated and analyzed using a phylodynamic approach. All the obtained strains belong to the CPV-2a lineage and associate with global strains in four monophyletic groups or clades. European and South American strains from all the countries here analyzed are representative of a widely distributed clade (Eur-I) that emerged in Southern Europe during 1990–98 to later spread to South America in the early 2000s. The emergence and spread of the Eur-I clade were correlated with a significant rise in the CPV effective population size in Europe and South America. The Asia-I clade includes strains from Asia and Uruguay. This clade originated in Asia during the late 1980s and evolved locally before spreading to South America during 2009–10. The third clade (Eur-II) comprises strains from Italy, Brazil, and Ecuador. This clade appears in South America as a consequence of an early introduction from Italy to Ecuador in the middle 1980s and has experienced extensive local genetic differentiation. Some strains from Argentina, Uruguay, and Brazil constitute an exclusive South American clade (SA-I) that emerged in Argentina in the 1990s. These results indicate that the current epidemiological scenario is a consequence of inter- and intracontinental migrations of strains with different geographic and temporal origins that set the conditions for competition and local differentiation of CPV populations. The coexistence and interaction of highly divergent strains are the main responsible for the drastic epidemiological changes observed in South America in the last two decades. This highlights the threat of invasion from external sources and the importance of whole-genome resolution to robustly infer the origin and spread of new CPV variants. From a taxonomic standpoint, the findings herein show that the classification system that uses a single amino acid to identify variants (2a, 2b, and 2c) within the CPV-2a lineage does not reflect phylogenetic relationships and is not suitable to analyze CPV evolution. In this regard, the identification of clades or sublineages within circulating CPV strains is the first step towards a genetic and evolutionary classification of the virus.

Investigation on Canine parvovirus circulation in dogs from Sicily (Italy) by biomolecular assay

Canine parvovirus type-2 (CPV-2) is a DNA virus that causes a very common worldwide diffused infectious disease in dogs. Since its appearance, the CPV-2 evolved generating novel genetic and antigenic variants (CPV-2a/2b/2c) which are distributed throughout the world. In the present study, the frequency of CPV-2 in a canine population in Sicily (Italy) was investigated, using a polymerase chain reaction (PCR) for a fragment of the VP2 gene. Out of a total of 673 samples from 370 dogs, submitted to the laboratory from July 2009 to August 2015, 265 samples (39.38%) were positive and these were further analyzed by restriction fragment length polymorphism (RFLP) and DNA sequence analysis. A high prevalence of the CPV-2c variant (79.56% of CPV-2 positive dogs) was observed in this survey, underlining that this type of CPV field isolate is prevalent circulating in Sicily. Sequence and phylogenetic analysis showed a close relationship with CPV-2a and CPV-2c strains from Europe and non-European countries. Considering that CPV-2c is reaching a worldwide distribution and that this variant is also affecting vaccinated dogs, efforts should be made towards the development of new CPV vaccines.

Epidemiological, clinical and pathological features of canine parvovirus 2c infection in dogs from southern Brazil

ABSTRACT: Canine parvovirus type 2c (CPV-2c) emerged in Europe in the early 2000’s and rapidly spread out worldwide. Clinical and molecular data have demonstrated its circulation in Brazilian dogs, yet detailed descriptions of cases are still lacking. This article describes the epidemiological, clinical and pathological features of 24 cases of CPV-2c-associated disease in dogs submitted to veterinary clinics and laboratory diagnosis in southern Brazil (2014-2016). Most affected dogs presented signs/lesions suggestive of parvovirus enteritis: diarrhea, vomiting, hyperemia and hemorrhage of the serous membrane of the small intestine, diffuse segmental granulation, atrophy of the villi, necrosis and fusion of crypts, squamous metaplasia and epithelial syncytia. A number of cases presented features divergent from the classical presentations, including a wide variation in the color of feces (reddish and/or yellowish, light-brownish, orange-brown and brownish), involvement of adults (4/24) and vaccinated dogs (12/24), extensive involvement of the small intestine (8/20) and the presence of pulmonary edema (7/24) and convulsions (3/24). Feces and intestinal fragments submitted to PCR for the CPV-2 VP2 gene and to virus isolation in cell culture yielded positive results in 100% and 58.3% (14/24) of the cases, respectively. Nucleotide sequencing revealed a high nucleotide identity in VP2 (99.4 to 100%) and a consistent mutation at amino acid 426 (asparagine to glutamic acid), considered a signature of CPV-2c. These results confirm the involvement of CPV-2c in the described cases and demonstrate the importance of CPV-2c infection among Brazilian dogs, calling attention of veterinarians to correctly diagnose the disease, mainly considering the frequent atypical presentations.

A rapid method for establishment of a reverse genetics system for canine parvovirus

Canine parvovirus (CPV) is an important and highly prevalent pathogen of dogs that causes acute hemorrhagic enteritis disease. Here, we describe a rapid method for the construction and characterization of a full-length infectious clone (rCPV) of CPV. Feline kidney (F81) cells were transfected with rCPV incorporating an engineered EcoR I site that served as a genetic marker. The rescued virus was indistinguishable from that of wild-type virus in its biological properties.

Prevalence and molecular epidemiology of Canine parvovirus 2 in diarrheic dogs in Colombia, South America: A possible new CPV-2a is emerging?

Since its identification in 1978, Canine parvovirus type 2 (CPV-2) has been considered a pathogen of great importance in the canine population because it causes severe enteritis with high mortality rates in pups. CPV-2 is a virus belonging to the family Parvoviridae. Currently, there are three described antigenic variants (CPV-2a, CPV-2b, and CPV-2c). CPV-2c is an emerging virus that is seen as a global health hazard. The objective of this work was to confirm the presence of CPV-2 in dogs with acute gastroenteritis compatible with parvovirus and to molecularly characterize the antigenic variants circulating in two regions of Colombia. An analytical cross-sectional study was conducted with fecal samples collected from 71 dogs showing signs of acute diarrhea. The samples were processed and polymerase chain reaction (PCR), restriction fragment length polymorphism analysis (RFLP), sequencing and phylogenetic analysis was performed to detect and characterize CPV. A total of 70.42% of the individuals were confirmed positive for CPV-2. Statistically differences were found in the presentation of CPV-2 between the evaluated regions. Phylogenetic analyses confirmed the presence of the antigenic variants CPV-2a/2b. Moreover, we found the presence of two conserved substitutions Asn428Asp and Ala514Ser in the VP2 protein suggesting the presence of a possible new CPV-2a variant circulating in Colombia. This study demonstrates the importance of the CPV 2a/2b in the region and highlights the importance of performing molecular studies for the early detection of new antigenic variants of CPV-2.

Genetic characterization of canine parvovirus type 2 subtypes in Maputo, Mozambique

Canine parvovirus type 2 (CPV-2) comprises three antigenic subtypes (2a, 2b and 2c) that have been reported in many countries. These subtypes cause serious disease in dogs with characteristic gastroenteritis signs. Little information has been documented in Africa about the genetic characterization of CPV-2. The aim of this study was to detect and to characterize the CPV-2 subtypes circulating in dogs admitted to Veterinary Clinics from two cities of Mozambique, Maputo and Matola, in 2010. A total of 40 field fecal samples were collected and tested for CPV-2 by polymerase chain reaction assay. The partial length VP2 gene of the positive samples were sequenced and genetically analyzed. Twenty-six (65%) fecal samples were positive for CPV-2. The restriction fragment length polymorphism analysis was also performed from positive samples and did not reveal the presence of CPV-2c subtype. The results of the sequencing revealed the presence of CPV-2a (n = 9) and CPV-2b (n = 17). No CPV-2 and CPV-2c were detected. Sequence analysis comparison showed nucleotide identities of 99.6-100% among our CPV-2 isolates. Amino acid analysis showed predicted amino acid changes. Phylogenetically, all of the CPV-2a strains isolated formed a cluster together with South African and Nigerian isolates. Most of Mozambican CPV-2b isolates also tended to cluster together with South African isolates; however, four were more closely related to French strain and one isolates to the American strain. The present study was the first to characterize the CPV-2 circulating in the Mozambican dog population.

Reliability of clinical diagnosis and laboratory testing techniques currently used for identification of canine parvovirus enteritis in clinical settings

Canine parvovirus type 2 (CPV-2) is the main etiological agent of viral enteritis in dogs. Actually in literature, CPV-2 has been reported with clinical signs that vary from the classical disease, and immunochromatography test and PCR technique have been introduced to veterinary hospitals to confirm CPV-2 diagnosis and other infections. However, the reliability of these techniques has been poorly analyzed. In this study, we evaluated the sensitivity and specificity of veterinary clinical diagnosis, immunochromatography test and PCR technique. Our data indicate that variations in the clinical signs of CPV-2 complicate the gathering of an appropriate diagnosis; and immunochromatography test and PCR technique do not have adequate sensitivity to diagnose positive cases.

Canine parvovirus: the worldwide occurrence of antigenic variants

The most important enteric virus infecting canids is canine parvovirus type 2 (CPV-2). CPV is the aetiologic agent of a contagious disease, mainly characterized by clinical gastroenteritis signs in younger dogs. CPV-2 emerged as a new virus in the late 1970s, which could infect domestic dogs, and became distributed in the global dog population within 2 years. A few years later, the virus's original type was replaced by a new genetic and antigenic variant, called CPV-2a. Around 1984 and 2000, virus variants with the single change to Asp or Glu in the VP2 residue 426 were detected (sometimes termed CPV-2b and -2c). The genetic and antigenic changes in the variants have also been correlated with changes in their host range; in particular, in the ability to replicate in cats and also host range differences in canine and other tissue culture cells. CPV-2 variants have been circulating among wild carnivores and have been well-documented in several countries around the world. Here, we have reviewed and summarized the current information about the worldwide distribution and evolution of CPV-2 variants since they emerged, as well as the host ranges they are associated with.

Occurrence of canine parvovirus in dogs from Henan province of China in 2009-2014

BACKGROUND

There is no information concerning the genotype of Canine parvovirus (CPV) currently circulating in Henan province, China. Therefore, the aim of the present study was to provide insights into the epidemiology and molecular characterization of CPV circulating in Henan province from 2009 to 2014.

RESULTS

Nineteen thousand nine hundred seven dogs from pet hospitals in the cities of Luoyang, Anyang, Jiaozuo, Sanmenxia, Xinxiang, Zhengzhou in Henan province between 2009 and 2014 were investigated. Over the 6-year period, 1169 CPV-positive cases were identified and the morbidity of CPV infection ranged from 4.16 to 8.06 %, although morbidity was not significant (P > 0.05) between 2009 and 2014. Factors associated with morbidity included sampling season, dog age, breed, vaccination status, and sex. CPV co-infection with coccidium (10.00 %), canine distemper virus (4.79 %), hookworm (2.40 %), canine coronavirus (1.11 %), roundworm (1.03 %), tapeworm (0.17 %) and Babesia spp. (0.09 %) were observed. The new CPV-2a variant was more prevalent than the new CPV-2b variant in Henan province. CPV 2c was not observed in this study.

CONCLUSIONS

The epidemiology of CPV infection and identification of the circulating genotypes in Henan province, China from 2009 to 2014 determined that the new CPV-2a variant was more prevalent.

High-yield production of canine parvovirus virus-like particles in a baculovirus expression system

An optimized VP2 gene from the current prevalent CPV strain (new CPV-2a) in China was expressed in a baculovirus expression system. It was found that the VP2 proteins assembled into virus-like particles (VLPs) with antigenic properties similar to those of natural CPV and with an especially high hemagglutination (HA) titer (1:2(20)). Dogs intramuscularly or orally immunized with VLPs produced antibodies against CPV with >1:80 hemagglutination inhibition (HI) units for at least 3 months. The CPV VLPs could be considered for use as a vaccine against CPV or as a platform for research on chimeric VLP vaccines against other diseases.

Co-Circulation of the Rare CPV-2c with Unique Gln370Arg Substitution, New CPV-2b with Unique Thr440Ala Substitution, and New CPV-2a with High Prevalence and Variation in Heilongjiang Province, Northeast China

To trace evolution of canine parvovirus-2 (CPV-2), a total of 201 stool samples were collected from dogs with diarrhea in Heilongjiang province of northeast China from May 2014 to April 2015. The presence of CPV-2 in the samples was determined by PCR amplification of the VP2 gene (568 bp) of CPV-2. The results revealed that 95 samples (47.26%) were positive for CPV-2, and they showed 98.8%–100% nucleotide identity and 97.6%–100% amino acid identity. Of 95 CPV-2-positive samples, types new2a (Ser297Ala), new2b (Ser297Ala), and 2c accounted for 64.21%, 21.05%, and 14.74%, respectively. The positive rate of CPV-2 and the distribution of the new2a, new2b and 2c types exhibited differences among regions, seasons, and ages. Immunized dogs accounted for 48.42% of 95 CPV-2-positive samples. Coinfections with canine coronavirus, canine kobuvirus, and canine bocavirus were identified. Phylogenetic analysis revealed that the identified new2a, new2b, and CPV-2c strains in our study exhibited a close relationship with most of the CPV-2 strains from China; type new2a strains exhibited high variability, forming three subgroups; type new2b and CPV-2c strains formed one group with reference strains from China. Of 95 CPV-2 strains, Tyr324Ile and Thr440Ala substitutions accounted for 100% and 64.21%, respectively; all type new2b strains exhibited the Thr440Ala substitution, while the unique Gln370Arg substitution was found in all type 2c strains. Recombination analysis using entire VP2 gene indicated possible recombination events between the identified CPV-2 strains and reference strains from China. Our data revealed the co-circulation of new CPV-2a, new CPV-2b, and rare CPV-2c, as well as potential recombination events among Chinese CPV-2 strains.

Resurgence of canine parvovirus 2a strain in the domestic dog population from Argentina

Ninety-three rectal swab samples were taken, from dogs suspected of canine parvovirus (CPV) infection and analyzed by PCR. A fragment of the VP2 gene, was amplified in 41 (44%) of them, resulting CPV positive samples. Sequencing analysis of these PCR products showed that 37 samples (90.2%) belonged to the CPV2c type, whereas four samples (9.8%) were identified as CPV2a, which has not been found since 2008. It was also found that 24 out of 37 CPV2c samples (65%), carried the mutation Thr440Ala, whereas this mutation was absent in the four CPV2a strains reported herein. Using phylogenetic analysis of the full length VP2 gene, which was amplified by PCR in six local samples, it was seen that CPV2a Argentine strains reported in this study, were genetically closer to a previous local CPV2a isolate (year 2003) and to a South African CPV2a strain, than to any of the recently reported Uruguayan CPV2a strains. The results obtained in this work, together with those reported previously in Uruguay strongly suggest that, in spite of the geographical proximity, wild type CPV strains undergo different evolutive pathways in each country, resulting in the prevalence of different strains in related dog populations. Further extensive epidemiological studies are needed in order to improve the understanding of CPV evolution.

Biology and Diseases of Dogs

Historically, the dog played an important role as a laboratory animal in biomedical research. Although numbers are declining, the use of dogs continues to be common in pharmacokinetics and cardiovascular studies. The normal biology of the dog as both a laboratory and a companion animal has been well studied and reference values are presented here as a clinical and experimental resource. This provides the necessary background to discuss the spontaneous diseases, including infectious and neoplastic conditions, prevalent in purpose bred as well as random source dogs used in biomedical research. In addition, diseases and conditions that arise secondary to the housing and experimental manipulation of dogs is discussed with emphasis on treatment and prevention.

A Ten-Year Molecular Survey on Parvoviruses Infecting Carnivores in Bulgaria

Parvoviruses represent the most important infectious agents that are responsible for severe to fatal disease in carnivores. This study reports the results of a 10‐year molecular survey conducted on carnivores in Bulgaria (n = 344), including 262 dogs and 19 cats with gastroenteritis, and 57 hunted wild carnivores. Real‐time polymerase chain reaction (qPCR), followed by virus characterization by minor groove binder (MGB) probe assays, detected 216 parvovirus positive dogs with a predominance of canine parvovirus type 2a (CPV‐2a, 79.17%) over CPV‐2b (18.52%) and CPV‐2c (2.31%). Rottweilers and German shepherds were the most frequent breeds among CPV‐positive pedigree dogs (n = 96). Eighteen cats were found to shed parvoviruses in their faeces, with most strains being characterized as FPLV (n = 17), although a single specimen tested positive for CPV‐2a. Only two wild carnivores were parvovirus positive, a wolf (Canis lupus) and a red fox (Vulpes vulpes), both being infected by CPV‐2a strains.

Common and emerging infectious diseases in the animal shelter

The beneficial role that animal shelters play is unquestionable. An estimated 3 to 4 million animals are cared for or placed in homes each year, and most shelters promote public health and support responsible pet ownership. It is, nonetheless, inevitable that shelters are prime examples of anthropogenic biological instability: even well-run shelters often house transient, displaced, and mixed populations of animals. Many of these animals have received minimal to no prior health care, and some have a history of scavenging or predation to survive. Overcrowding and poor shelter conditions further magnify these inherent risks to create individual, intraspecies, and interspecies stress and provide an environment conducive to exposure to numerous potentially collaborative pathogens. All of these factors can contribute to the evolution and emergence of new pathogens or to alterations in virulence of endemic pathogens. While it is not possible to effectively anticipate the timing or the pathogen type in emergence events, their sites of origin are less enigmatic, and pathologists and diagnosticians who work with sheltered animal populations have recognized several such events in the past decade. This article first considers the contribution of the shelter environment to canine and feline disease. This is followed by summaries of recent research on the pathogenesis of common shelter pathogens, as well as research that has led to the discovery of novel or emerging diseases and the methods that are used for their diagnosis and discovery. For the infectious agents that commonly affect sheltered dogs and cats, including canine distemper virus, canine influenza virus, Streptococcus spp, parvoviruses, feline herpesvirus, feline caliciviruses, and feline infectious peritonitis virus, we present familiar as well as newly recognized lesions associated with infection. Preliminary studies on recently discovered viruses like canine circovirus, canine bocavirus, and feline norovirus indicate that these pathogens can cause or contribute to canine and feline disease.

Genotyping and pathobiologic characterization of canine parvovirus circulating in Nanjing, China

BACKGROUND

Canine parvovirus (CPV) is an important pathogen that causes acute enteric disease in dogs. It has mutated and spread throughout the world in dog populations. We provide an update on the molecular characterization of CPV that circulated in Nanjing, a provincial capital in China between 2009 and 2012.

RESULTS

Seventy rectal swab samples were collected from the dogs diagnosed with CPV infection in 8 animal hospitals of Nanjing. Sequence analysis of VP2 genes of 31 samples revealed that 29 viral strains belonged to CPV-2a subtype, while other two strains were classified into CPV-2b. To investigate the pathogenicity of the prevalent virus, we isolated CPV-2a and performed the animal experiment. Nine beagles were inoculated with 105.86 of 50% tissue culture infectious doses (TCID50) of the virus. All the experimentally infected beagles exhibited mild to moderate mucoid or watery diarrhea on day 4 post-infection (p.i.). On day 9 p.i., characteristic histopathological lesions were clearly observed in multiple organs of infected dogs, including liver, spleen, kidney, brain and all segments of the small and large intestines, while viral DNA and antigen staining could be detected in the sampled tissues. It is notable that canine parvovirus was isolated in one from two brain samples processed.

CONCLUSION

Our results indicated that CPV-2a is the predominant subtype in Nanjing of China. And this virus caused extensive lesions in a variety of tissues, including the brain.

High local genetic diversity of canine parvovirus from Ecuador

Canine parvovirus (CPV) comprises three antigenic variants (2a, 2b, and 2c) that are distributed globally with different frequencies and levels of genetic variability. CPVs from central Ecuador were herein analyzed to characterize the strains and to provide new insights into local viral diversity, evolution, and pathogenicity. Variant prevalence was analyzed by PCR and partial sequencing for 53 CPV-positive samples collected during 2011 and 2012. The full-length VP2 gene was sequenced in 24 selected strains and a maximum-likelihood phylogenetic tree was constructed using both Ecuadorian and worldwide strains. Ecuadorian CPVs have a remarkable genetic diversity that includes the circulation of all three variants and the existence of different evolutionary groups or lineages. CPV-2c was the most prevalent variant (54.7%), confirming the spread of this variant in America. Ecuadorian CPV-2c strains clustered in two lineages, which represent the first evidence of polyphyletic CPV-2c circulating in South America. CPV-2a strains constituted 41.5% of the samples and clustered in a single lineage. The two detected CPV-2b strains (3.8%) were clearly polyphyletic and appeared related to Ecuadorian CPV-2a or foreign CPV-2b strains. Besides the substitution at residue 426 that is used to identify the variants, two amino acid changes occurred in Ecuadorian strains: Val139Iso and Thr440Ser. Ser(440) occurred in a biologically relevant domain of VP2 and is here described for the first time in CPV. The associations of Ecuadorian CPV-2c and CPV-2a with clinical symptoms indicate that dull mentation, hemorrhagic gastroenteritis and hypothermia occurred more frequently in infection with CPV-2c than with CPV-2a.

Isolation and characterization of canine parvovirus type 2C (CPV-2C) from symptomatic puppies

Canine parvovirus type 2 (CPV-2) is a leading cause of diarrhea in puppies in several parts of the world. In this study CPV-2 was detected and recovered from puppies showing clinical disease from Montevideo, Uruguay. Samples were processed and used to infect CRFK and MDCK cells in order to isolate the virus. Out of twelve, two samples were positive for CPV-2. A genomic region of 583 bp was amplified and the molecular characterization was performed by sequencing, phylogenetic analysis and Restriction Fragment Length Polymorphism (RFLP). Two isolated viruses (UY1 and UY2) were CPV-2c-like viruses. The comparison between the cytophatic effect (CPE) of CPV-2 (vaccinal virus) and CPV-2c (isolated virus) on primary canine cells cultures and on CRFK line cells, demonstrated that CPV-2c is less citopathogenic in CRFK than in primary cultures. Our study represents the first report on isolation and characterization of canine parvovirus type 2c (CPV-2c) in cell cultures from South American dogs.

Typing of canine parvovirus strains circulating in Brazil between 2008 and 2010

Detection and characterisation of the canine parvovirus (CPV-2) strains that are currently circulating are essential for the understanding of viral evolution and the development of measures to control its spread. In the present study, stool samples from 144 dogs were analysed by polymerase chain reaction (PCR) for CPV-2, and 29.2% (42/144) of them were positive. From the 42 positive strains, 71.4% (30) of the dogs had signs of haemorrhagic gastroenteritis. The sequencing of the 583 bp fragment of the VP2 gene from the positive strains identified 78.6% (33/42) of them as type 2c, 19% (8/42) as type 2b and 2.4% (1/42) as type 2a. A phylogenetic analysis of the variants circulating in the canine population of Brazil showed that they are very similar to those found in other countries and type 2c has become the predominant type circulating in Brazil.

Characterization of the partial VP2 gene region of canine parvoviruses in domestic cats from Turkey

Canine parvoviruses (CPVs) is a category comprising three closely related viruses, CPV, feline panleukopenia virus (FPLV), and mink enteritis virus, all of which cause serious diseases, especially in young cats. In this study, molecular detection and genetic analysis of a partial VP2 gene region of CPVs from domestic cats living in Turkey between 2006 and 2010 was performed by PCR amplification and sequence analysis. The results indicated that CPV-2a, CPV-2c, and FPLV were circulating in vaccinated and unvaccinated cats. This is the first description of molecular characterization of CPVs in domestic cats from Turkey.

Recent spreading of a divergent canine parvovirus type 2a (CPV-2a) strain in a CPV-2c homogenous population

Canine parvovirus type 2 (CPV-2), which causes acute hemorrhagic enteritis in dogs, is comprised of three antigenic variants (2a, 2b, and 2c) that are distributed worldwide with different frequencies. Variant prevalence was analyzed in 150 CPV-2-positive samples collected from the Uruguayan dog population in 2007-2010. Samples were analyzed with polymerase chain reaction, restriction fragment length polymorphism, and sequencing of the coding region for the largest and most variable loop of the VP2 capsid protein. CPV-2c was the only strain detected from 2007 to 2009. Uruguayan CPV-2c showed high homogeneity in both nucleotide and amino acid sequences, indicating a low level of genetic variability. In 2010, an unexpected epidemiological change occurred in Uruguay as a consequence of the appearance of a novel CPV-2a strain. This variant rapidly spread through the Uruguayan dog population and was detected in 20 of the 52 cases (38%) analyzed in 2010. CPV-2a sequences were identical in all field viruses analyzed, and in addition to the characteristic 426Asn residue, the sequences showed amino acid substitutions (267Tyr, 324Ile, and 440Ala) not observed in the Uruguayan CPV-2c. These data and the first detection in April 2010 suggest that the CPV-2a variant recently emerged in Uruguay and underwent clonal expansion. This observation is the first case in which a CPV-2a variant increased its frequency in a dog population where CPV-2c was prevalent. Our results emphasize the dynamic changes in CPV variants and highlight the importance of ongoing surveillance programs to provide a better understanding of virus epidemiology.

Canine parvovirus--a review of epidemiological and diagnostic aspects, with emphasis on type 2c

Canine parvovirus type 2 (CPV-2) emerged in late 1970s causing severe epizootics in kennels and dog shelters worldwide. Soon after its emergence, CPV-2 underwent genetic evolution giving rise consecutively to two antigenic variants, CPV-2a and CPV-2b that replaced progressively the original type. In 2000, a new antigenic variant, CPV-2c, was detected in Italy and rapidly spread to several countries. In comparison to the original type CPV-2, the antigenic variants display increased pathogenicity in dogs and extended host range, being able to infect and cause disease in cats. Epidemiological survey indicate that the newest type CPV-2c is becoming prevalent in different geographic regions and is often associated to severe disease in adult dogs and also in dogs that have completed the vaccination protocols. However, the primary cause of failure of CPV vaccination is interference by maternally derived immunity. Diagnosis of CPV infection by traditional methods has been shown to be poorly sensitive, especially in the late stages of infections. New diagnostic approaches based on molecular methods have been developed for sensitive detection of CPV in clinical samples and rapid characterisation of the viral type. Continuous surveillance will help assess whether there is a real need to update currently available vaccines and diagnostic tests.

Study of canine parvovirus evolution: comparative analysis of full-length VP2 gene sequences from Argentina and international field strains

The continuous emergence of new strains of canine parvovirus (CPV), poorly protected by current vaccination, is a concern among breeders, veterinarians, and dog owners around the world. Therefore, the understanding of the genetic variation in emerging CPV strains is crucial for the design of disease control strategies, including vaccines. In this paper, we obtained the sequences of the full-length gene encoding for the main capsid protein (VP2) of 11 canine parvovirus type 2 (CPV-2) Argentine representative field strains, selected from a total of 75 positive samples studied in our laboratory in the last 9 years. A comparative sequence analysis was performed on 9 CPV-2c, one CPV-2a, and one CPV-2b Argentine strains with respect to international strains reported in the GenBank database. In agreement with previous reports, a high degree of identity was found among CPV-2c Argentine strains (99.6-100% and 99.7-100% at nucleotide and amino acid levels, respectively). However, the appearance of a new substitution in the 440 position (T440A) in four CPV-2c Argentine strains obtained after the year 2009 gives support to the variability observed for this position located within the VP2, three-fold spike. This is the first report on the genetic characterization of the full-length VP2 gene of emerging CPV strains in South America and shows that all the Argentine CPV-2c isolates cluster together with European and North American CPV-2c strains.

Evolution of canine parvovirus in Argentina between years 2003 and 2010: CPV2c has become the predominant variant affecting the domestic dog population

The current frequency of Canine Parvovirus variants (CPV2a, CPV2b and CPV2c) in the Argentine dog population was investigated by PCR amplification of a 583 bp fragment in the VP2 gene. From a total of 79 rectal swab samples that have been submitted to our laboratory since 2008, 55 (69.6%) resulted positive and were further analyzed by direct DNA sequencing. Fifty positives samples (91%) were characterized as CPV2c variant, which appeared in Argentina in the year 2003 and has been the prevalent type since 2008, whereas CPV2a and CPV2b, still found in Argentine dogs, were represented in 3.6% and 5.4% of the population, respectively. Considering that CPV2c is spreading worldwide, and that this variant is also affecting vaccinated dogs, efforts should be made towards the development of new matched CPV vaccines.

Canine Parvovirus Epidemiology in Bulgaria

Canine parvovirus 2 (CPV-2) emerged in 1978 as one of the most pathogenic etiologic agents in dogs. Under the influence of evolution, the original CPV-2 was replaced, a few years later, by 2 variants, CPV-2a and CPV-2b. In 2000, a new variant, CPV-2c, was detected first in Italy and later in other countries. The current study was conducted to provide data about the CPV types circulating in Bulgaria. Forty-two fecal samples from dogs with clinical signs of parvovirosis, collected between June 2009 and February 2010, were tested for CPV using a rapid test based on detection of CPV antigens and a real-time polymerase chain reaction (PCR) for detection of viral DNA. Positive samples were characterized by means of minor groove binder probe PCR assays. Forty samples were positive, of which 30 were identified as CPV-2a, 9 as CPV-2b, and 1 as CPV-2c. The results from this molecular investigation of CPV show the prevalence of type 2a and occurrence of type 2c for the first time in Bulgaria.

Partial VP2 sequencing of canine parvovirus (CPV) strains circulating in the state of Rio de Janeiro, Brazil: detection of the new variant CPV-2c

Canine parvovirus (CPV) is the most important enteric virus for dogs and it seems to be undergoing continuous evolution, generating new genetic and antigenic variants throughout the world. The aim of this study was to analyze the distribution of CPV variants from 1995 to 2009 and to investigate the circulation of the new variant CPV-2c in Rio de Janeiro, Brazil. In addition, the clinical features of CPV infection were also reported. After CPV laboratorial confirmation by HA/HI and PCR, thirty-two fecal samples were analyzed by sequencing a 583-bp fragment of the VP2 gene. One sample, collected in 2008 was typed as the new type CPV-2c. All samples from 1995 to 2003 were identified as "new CPV-2a". From 2004 to 2006, both "new CPV-2a" and CPV-2b were observed. From 2006 to 2009, most of the samples were characterized as CPV-2b. The classical signs of CPV enteritis were observed in 16/18 CPV-2a and 5/13 CPV-2b infected puppies. These results show that continuous epidemiological surveillance of CPV strain distribution is essential for studying the patterns of CPV-2a and 2b spread and for determining whether the new variant CPV-2c has become permanently established in Brazilian canine population.

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.

Characterization of Canine parvovirus 2 variants circulating in Greece

The aim of the present study was to characterize Canine parvovirus 2 (CPV-2) variants currently circulating in Greece. Between March 2008 and March 2009, 167 fecal samples were collected from diarrheic dogs from different regions of Greece. Canine parvovirus 2 was detected by standard polymerase chain reaction, whereas minor groove binder probe assays were used to distinguish genetic variants and discriminate between vaccine and field strains. Of 84 CPV-2-positive samples, 81 CPV-2a, 1 CPV-2b, and 2 CPV-2c were detected. Vaccine strains were not detected in any sample. Sequence analysis of the VP2 gene of the 2 CPV-2c viruses revealed up to 100% amino acid identity with the CPV-2c strains previously detected in Europe. The results indicated that, unlike other European countries, CPV-2a remains the most common variant in Greece, and that the CPV-2c variant found in Europe is also present in Greece.

Misleading results of the MboII-based identification of type 2a canine parvovirus strains from Hungary reacting as type 2c strains

Type 2 canine parvovirus (CPV2) infection is one of the most frequent causes of death in the young, susceptible canine populations worldwide. Since its emergence in the 1970s, several variants have been described. In the present study the authors describe the genetic analysis of 24 Hungarian CPV2 strains collected from 2004 to 2008. Surprisingly, the genetic and phylogenetic investigations of all these strains revealed that all of them were type 2a CPVs. On the other hand, the genetic analysis provided substantial evidence to demonstrate that due to a seemingly constant point mutation present in most of the Hungarian CPV2a strains, a previously described MboII-based rapid identification of CPV2c strains unfortunately cannot be reliably used any more.

Monitoring of canine parvovirus (CPV) strains detected in vaccinated puppies in Brazil

The objective of this study was to investigate, by partial sequencing of VP2 protein, the variability of CPV detected in 37 fecal samples collected from vaccinated puppies with enteritis. Laboratorial diagnosis of CPV was confirmed by HA/HI and PCR and, for sequencing analyses, two different regions of the VP2 gene were amplified by PCR. From 1995 to 2004, all strains were characterized as CPV-2a. After that, both CPV-2a and CPV-2b were detected. All CPV-2a showed a non-synonymous mutation in the residue 297 (Ser→Ala). A synonymous substitution at the AA 574 was also observed in 15/37 samples. Our findings indicate that the cases of vaccine failure are most likely not associated to the mutations detected in the sequenced regions. However, the monitoring of genotyping mutations that led to new CPV strains is essential to determinate if current vaccines will keep providing protection against all new future variants.

Characterisation of canine parvovirus strains isolated from cats with feline panleukopenia

Unlike the original canine parvovirus type 2 (CPV-2), CPV-2 variants have gained the ability to replicate in vivo in cats but there is limited information on the disease patterns induced by these variants in the feline host. During 2008, two distinct cases of parvoviral infection were diagnosed in our laboratories. A CPV-2a variant was identified in a 3-month-old Persian kitten displaying clinical sign of feline panleukopenia (FPL) (acute gastroenteritis and marked leukopenia) and oral ulcerations, that died eight days after the onset of the disease. Two pups living in the same pet shop as the cat were found to shed a CPV-2a strain genetically identical to the feline virus and were likely the source of infection. Also, non-fatal infection by a CPV-2c strain occurred in a 2.5-month-old European shorthair kitten displaying non-haemorrhagic diarrhoea and normal white blood cell counts. By sequence analysis of the major capsid protein (VP2) gene, the feline CPV-2c strain showed 100% identity to a recent canine type-2c isolate. Both kittens had been administered multivalent vaccines against common feline pathogens including FPL virus. Whether and to which extent the FPL vaccines can protect cats adequately from the antigenic variants of CPV-2 should be assessed.

Western European epidemiological survey for parvovirus and coronavirus infections in dogs

An epidemiological survey for canine parvovirus (CPV) and canine coronavirus (CCoV) infections was conducted in Western Europe. A total of 156 faecal samples were collected from dogs with diarrhoea in Spain (n = 47), Italy (n = 39), France (n = 26), Germany (n = 21), the United Kingdom (n = 8), Belgium (n = 10), and the Netherlands (n = 5). Using molecular assays for virus detection and characterisation, CPV and CCoV were found to be widespread in European dog populations, either alone or in mixed infections. In agreement with previous reports, the original type CPV-2 was shown not to circulate in European dogs. The recently identified virus variant CPV-2c was predominant in Italy and Germany and present at high rates in Spain and France but was not detected in the UK or Belgium. Except for the UK, CCoV genotype I was identified in all European countries involved in the survey, albeit at a lower prevalence rates than CCoV genotype II.