Canine parvoviruses in New Zealand form a monophyletic group distinct from the viruses circulating in other parts of the world

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.

Detection of Selected Canine Viruses in Nigerian Free-Ranging Dogs Traded for Meat Consumption

Animal trade favors the spreading of emerging and re-emerging pathogens. Concerns have been previously expressed regarding the risks of dog trade in spreading zoonotic pathogens in Nigeria. However, the role of these dogs in disseminating highly pathogenic canine viruses has not yet been explored. The present study aimed to identify selected canine viruses in dogs traded for meat consumption in Nigeria. A total of 100 blood samples were screened for carnivore protoparvovirus-1 (CPPV-1), canine adenovirus 1/2 (CAdV-1/2), canine circovirus (CaCV), and canine distemper virus (CDV) by using real-time PCR and conventional PCR and/or sequencing. CPPV-1 DNA was identified in 83% of canine samples while CaCV DNA and CDV RNA were detected in 14% and 17% of the dog samples, respectively. None of the dogs tested positive for CAdV-1/2. The CaCVs identified in this study clustered along with other European, Asian, and American strains. Moreover, CDV strains identified in Nigeria clustered in a separate lineage with the closest genetic relatedness to the Europe-South America-1 clade. Further surveys prior to and after arrival of dogs at the slaughtering points are required to clarify the real virus burden in these animals.

Tracing the Genetic Evolution of Canine Parvovirus Type 2 (CPV-2) in Thailand

Canine parvovirus type 2 (CPV-2) is responsible for hemorrhagic gastroenteritis in dogs worldwide. High genomic substitution rates in CPV-2 contribute to the progressive emergence of novel variants with increased ability to evade the host immune response. Three studies have analyzed the genomic mutations of CPV-2 variants in Thailand. These investigations were independently conducted at different timepoints. Thus, a retrospective integrated analysis of CPV-2 genomic mutations has not been fully performed. Our study aimed at evaluating the evolutionary changes in CPV-2 in Thailand from 2003 to 2019. Two hundred and sixty-eight Thai CPV-2 nucleotide sequences were used for multiple amino acid sequence alignment and phylogenetic analyses. From 2003 to 2010, CPV-2a and -2b were the only variants detected. CPV-2c, emerged in 2014, replacing CPV-2a and -2b, and has become a major variant in 2019. Phylogenetic analysis revealed that the proposed mutation pattern of VP2 amino acid residues could help distinguish Thai CPV-2 variants. This comprehensive examination provides insight into the genomic evolution of CPV-2 in Thailand since its first reporting in 2003, which may facilitate the surveillance of the potential genetic alteration of emergent CPV-2 variants.

Genomic Variability of Canine Parvoviruses from a Selected Population of Dogs and Cats in Sri Lanka

The aim of the study was to identify canine parvovirus type 2 (CPV-2) subtypes circulating among a selected population of domestic dogs and cats in Sri Lanka and to investigate the evolutionary patterns among Sri Lankan viruses in the context of contemporary global CPV-2 sequences. Altogether, 40/61 (65.6%) samples tested were positive for CPV-2 DNA, including 31/48 (64.6%) dogs and 9/13 (69%) cats. All three subtypes (CPV-2a, CPV-2b and CPV-2c) were detected, with CPV-2a being most common. International median joining haplotype network of 291 CPV-2 sequences suggested that there was little barrier for CPV-2 moving between different geographical regions worldwide, including Sri Lanka, and that there was no correlation between the genetic structure within the molecular network and the decade of sample collection. By contrast, there was correlation between CPV-2 subtype and genetic structure, both within the international network and within the network built from 31 Sri Lankan CPV-2 sequences only. The structure within the latter was not correlated with the location of the veterinary clinic where the samples were submitted, the age or species of the host. Altogether, we have shown that there is considerable variability of CPV-2 genotypes circulating in Sri Lanka, which is likely driven by both local evolution and introduction from other countries. The similarity of CPV-2 obtained from cats and dogs suggests that cats may play a role in the epidemiology of CPV-2 in Sri Lanka.

Predominance of canine parvovirus 2b in Japan: an epidemiological study during 2014-2019

Canine parvovirus 2 (CPV-2) is an important pathogen of domestic dogs and wild canids. In Japan, CPV-2 infection is one of the most common infectious diseases of dogs. We analyzed samples collected between 2014 and 2019 to identify antigenic variants of CPV-2 in dogs in Japan. Our results demonstrated that the CPV-2b variant was predominant. The CPV-2c variant was not found among our samples. Our findings demonstrate that the distribution of CPV-2 antigenic variants in Japan was more similar to that in Australia than to that in neighboring countries in Asia.

Analysis of canine parvoviruses circulating in Australia reveals predominance of variant 2b and identifies feline parvovirus-like mutations in the capsid proteins

Canine parvovirus (CPV) is a major enteric pathogen of dogs worldwide that emerged in the late 1970s from a feline parvovirus (FPV)-like ancestral virus. Shortly after its emergence, variant CPVs acquired amino acid (aa) mutations in key capsid residues, associated with biological and/or antigenic changes. This study aimed to identify and analyse CPV variants and their capsid mutations amongst Australian dogs, to gain insights into the evolution of CPV in Australia and to investigate relationships between the disease and vaccination status of dogs from which viruses were detected. CPV VP2 sequences were amplified from 79 faecal samples collected from dogs with parvoviral enteritis at 20 veterinary practices in five Australian states. The median age at diagnosis was 4 months (range 1-96 months). Only 3.7% of dogs with vaccination histories had completed recommended vaccination schedules, while 49% were incompletely vaccinated and 47.2% were unvaccinated. For the first time, CPV-2b has emerged as the dominant antigenic CPV variant circulating in dogs with parvoviral enteritis in Australia, comprising 54.4% of viruses, while CPV-2a and CPV-2 comprised 43.1% and 2.5%, respectively. The antigenic variant CPV-2c was not identified. Analysis of translated VP2 sequences revealed a vast repertoire of amino acid (aa) mutations. Several Australian CPV strains displayed signatures in the VP2 protein typical of Asian CPVs, suggesting possible introduction of CPV strains from Asia, and/or CPV circulation between Asia and Australia. Canine parvoviruses were identified containing aa residues typical of FPV at key capsid (VP2) positions, representing reverse mutations or residual mutations retained from CPV-2 during adaptation from an FPV-like ancestor, suggesting that evolutionary intermediates between CPV-2 and FPV are circulating in the field. Similarly, intermediates between CPV-2a-like viruses and CPV-2 were also identified. These findings help inform a better understanding of the evolution of CPV in dogs.

Genetic characterization of Carnivore Parvoviruses in Spanish wildlife reveals domestic dog and cat-related sequences

The impact of carnivore parvovirus infection on wild populations is not yet understood; disease signs are mainly developed in pups and assessing the health of litters in wild carnivores has big limitations. This study aims to shed light on the virus dynamics among wild carnivores thanks to the analysis of 213 samples collected between 1994 and 2013 in wild ecosystems from Spain. We determined the presence of carnivore parvovirus DNA by real-time PCR and sequenced the vp2 gen from 22 positive samples to characterize the strains and to perform phylogenetic analysis. The presence of carnivore parvovirus DNA was confirmed in 18% of the samples, with a higher prevalence detected in wolves (Canis lupus signatus, 70%). Fourteen sequences belonging to nine wolves, three Eurasian badgers (Meles meles), a common genet (Genetta genetta) and a European wildcat (Felis silvestris) were classified as canine parvovirus 2c (CPV-2c); five sequences from three wolves, a red fox (Vulpes vulpes) and a stone marten (Martes foina) as CPV-2b; and three sequences from a badger, a genet and a stone marten as feline parvovirus (FPV). This was the first report of a wildcat infected with a canine strain. Sequences described in this study were identical or very close related to others previously found in domestic carnivores from distant countries, suggesting that cross-species transmission takes place and that the parvovirus epidemiology in Spain, as elsewhere, could be influenced by global factors.

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.

Molecular insight into Italian canine parvovirus heterogeneity and comparison with the worldwide scenario

Canine parvovirus is one of the most frequent pathogens of young dogs, causing severe clinical manifestations. Its phenotypic variability led to an antigenic-based classification into different variants, which have been reported worldwide. To update the Italian distribution of CPV, a molecular survey was performed on 100 geographically-annotated samples collected from 2008 to 2015 by full VP2 sequencing. All three antigenic variants (CPV-2a, 2b, 2c) were detected during the studied period, being CPV-2a the most prevalent (60%). Locally, CPV appeared widely distributed, without any regional or temporal clustering, demonstrating an outstanding and uncontrolled within-country viral spreading. The Italian sequences were also contextualized in the International scenario. The analysis of CPV worldwide molecular epidemiology highlighted the remarkable genetic heterogeneity of the circulating strains and their broad distribution. In fact, a frequent viral exchange among Countries, was proven both over short and long distances, involving haplotypes persisting through time. The reported information on viral dissemination patterns appears crucial for understanding the introduction routes of new variants or strains, which could complicate the epidemiological scenario, affect the disease patterns, show possible differential virulence and clinical relevance of emerging strains especially, and impair the vaccine efficacy.

Emergence of novel canine parvovirus type 2 and its pathogenesis in raccoon dogs

Three parvoviruses were isolated from the raccoon dogs experiencing severe enteritis, named RDPV-DP1, RDPV-DP2 and RDPV-DP3, respectively. The VP2 genes of the 3 isolates showed 99.9% identity at the nucleotide level, and shared 99.1%-99.5% identity with the reference CPVs. The RDPVs resembled original CPV-2, but with four mutations. The RDPVs displayed S297A of VP2 protein as CPV-2a or CPV-2b prevalent throughout most of the world. Residue N375D was found in the 3 isolates, resembling CPV-2a/2b/2c. And the 3 isolates had a natural mutation of VP2 residue V562L, which is adjacent to residue 564 and 568 and might be involved in host range. Interestingly, VP2 S27T was firstly found in the isolates. Phylogenetic analysis of VP2 genes revealed that the RDPVs were clustered into one small evolutionary branch and shared the identical branch with 7 CPV-2 isolates from raccoon dogs and one CPV-2 isolate from fox, not with CPV vaccine viruses. Phylogenetic analysis of NS1 genes demonstrated that the RDPVs shared the identical branch with the reference CPV-2a/2b/2c. Experimental infection showed that RDPV infection caused a high morbidity in raccoon dogs. It implied that the RDPV was virulent to raccoon dogs and continued to evolve in China.

Evolutionary and genetic analysis of the VP2 gene of canine parvovirus

BACKGROUND

Canine parvovirus (CPV) type 2 emerged in 1978 in the USA and quickly spread among dog populations all over the world with high morbidity. Although CPV is a DNA virus, its genomic substitution rate is similar to some RNA viruses. Therefore, it is important to trace the evolution of CPV to monitor the appearance of mutations that might affect vaccine effectiveness.

RESULTS

Our analysis shows that the VP2 genes of CPV isolated from 1979 to 2016 are divided into six groups: GI, GII, GIII, GIV, GV, and GVI. Amino acid mutation analysis revealed several undiscovered important mutation sites: F267Y, Y324I, and T440A. Of note, the evolutionary rate of the CPV VP2 gene from Asia and Europe decreased. Codon usage analysis showed that the VP2 gene of CPV exhibits high bias with an ENC ranging from 34.93 to 36.7. Furthermore, we demonstrate that natural selection plays a major role compared to mutation pressure driving CPV evolution.

CONCLUSIONS

There are few studies on the codon usage of CPV. Here, we comprehensively studied the genetic evolution, codon usage pattern, and evolutionary characterization of the VP2 gene of CPV. The novel findings revealing the evolutionary process of CPV will greatly serve future CPV research.

Multiplex Amplification Refractory Mutation System PCR (ARMS-PCR) provides sequencing independent typing of canine parvovirus

Canine parvovirus-2 antigenic variants (CPV-2a, CPV-2b and CPV-2c) ubiquitously distributed worldwide in canine population causes severe fatal gastroenteritis. Antigenic typing of CPV-2 remains a prime focus of research groups worldwide in understanding the disease epidemiology and virus evolution. The present study was thus envisioned to provide a simple sequencing independent, rapid, robust, specific, user-friendly technique for detecting and typing of presently circulating CPV-2 antigenic variants. ARMS-PCR strategy was employed using specific primers for CPV-2a, CPV-2b and CPV-2c to differentiate these antigenic types. ARMS-PCR was initially optimized with reference positive controls in two steps; where first reaction was used to differentiate CPV-2a from CPV-2b/CPV-2c. The second reaction was carried out with CPV-2c specific primers to confirm the presence of CPV-2c. Initial validation of the ARMS-PCR was carried out with 24 sequenced samples and the results were matched with the sequencing results. ARMS-PCR technique was further used to screen and type 90 suspected clinical samples. Randomly selected 15 suspected clinical samples that were typed with this technique were sequenced. The results of ARMS-PCR and the sequencing matched exactly with each other. The developed technique has a potential to become a sequencing independent method for simultaneous detection and typing of CPV-2 antigenic variants in veterinary disease diagnostic laboratories globally.

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.

Molecular epidemiology of canine parvovirus in Morocco

Since it first emergence in the mid-1970's, canine parvovirus 2 (CPV-2) has evolved giving rise to new antigenic variants termed CPV-2a, CPV-2b and CPV-2c, which have completely replaced the original strain and had been variously distributed worldwide. In Africa limited data are available on epidemiological prevalence of these new types. Hence, the aim of the present study was to determine circulating variants in Morocco. Through TaqMan-based real-time PCR assay, 91 samples, collected from symptomatic dogs originating from various cities between 2011 and 2015, were diagnosed. Positive specimens were characterised by means of minor groove binder (MGB) probe PCR. The results showed that all samples but one (98.9%) were CPV positive, of which 1 (1.1%) was characterised as CPV-2a, 43 (47.7%) as CPV-2b and 39 (43.3%) as CPV-2c. Interestingly, a co-infection with CPV-2b and CPV-2c was detected in 4 (4.4%) samples and 3 (3.3%) samples were not characterised. Sequencing of the full VP2 gene revealed these 3 uncharacterised strains as CPV-2c, displaying a change G4068A responsible for the replacement of aspartic acid with asparagine at residue 427, impacting the MGB probe binding. In this work we provide a better understanding of the current status of prevailing CPV strains in northern Africa.