Canine parvovirus in North-East India: a phylogenetic and evolutionary analysis

Canine parvovirus type 2 (CPV-2) infection in dogs is considered as one of the most common cause of morbidity and mortality in young dogs and continues to occur with high incidence worldwide. Despite a single-stranded DNA virus, CPV-2 possesses a high mutation rate which has led to the development of new variants from time to time. These variants are classically classified based on the amino acid markers present in the VP2 gene. In this study, we examined 20 different cases of CPV-2 infection from seven different states of the North East region (NER) of India. The near-complete genome sequences of all these isolates were subjected to phylodynamic and phylogeographic analysis to evaluate the genetic diversity and geographical spread of CPV-2 variants. Analysis of the deduced amino acid sequences revealed residues characteristic of the 'Asian CPV-2c lineage' in all the 20 sequences confirming it as the dominant strain circulating in NER, India. The phylogenetic analysis based on the whole genome showed that all 20 sequences formed a monophyletic clade together with other Asian CPV-2c sequences. Furthermore, phylogeographic analysis based on the VP2 gene showed the likely introduction of Asian CPV-2c strain to India from China. This study marks the first comprehensive report elucidating the molecular epidemiology of CPV-2 in India.

Whole-genome sequence analysis of canine parvovirus reveals replacement with a novel CPV-2c strain throughout India

Canine parvovirus (CPV) infection causes severe gastroenteritis in canines, with high mortality in puppies. This virus evolved from feline panleukopenia virus by altering its transferrin receptor (TfR), followed by the emergence of CPV-2 variants in subsequent years with altered immunodominant amino acid residues in the VP2 protein. While previous studies have focused on the VP2 gene, there have been fewer studies on non-structural protein (NS1 and NS2) genes. In the present study, CPV genome sequences from clinical samples collected from canines throughout India in 2023, previous Indian CPV isolates from 2009-2019, and the current Indian CPV vaccine strain were compared. The study showed that the CPV-2c (N426E) variant had almost completely replaced the previously dominant CPV-2a variant (N426) in India. The Q370R mutation of VP2 was the most common change in the recent CPV-2c strain (CPV-2c 370Arg variant). Phylogenetic analysis showed the existence of three clades among the recent CPV-2c strains, and sequence analysis identified several new sites of positive selection in the VP1 (N-terminus), VP2, NS1, and NS2 protein-encoding genes in recent CPV strains, indicating the emergence of new CPV-2c variants with varied antigenic and replication properties. The predominant 'CPV-2c 370Arg variants' were grouped with the Chinese and Nigerian CPV-2c strains but were separate from the CPV vaccine strain and earlier isolates from our repository. VP2 epitope analysis predicted nine amino acid variations (including two new variations) in four potential linear B-cell epitopes in the CPV-2c 370Arg variants that might make vaccine failure more likely. This pan-Indian study lays the foundation for further research concerning the dynamics of virus evolution and understanding genetic mutations.

Cross-Neutralization of Vanguard C4 Vaccine Against Australian Isolates of Canine Parvovirus Variants CPV-2a, CPV-2b, and CPV-2c

Canine parvovirus type 2 (CPV-2) remains one of the most significant viral pathogens in dogs in Australia and worldwide despite the availability of safe and effective CPV vaccines. At least three different variants of CPV-2 have emerged and spread all around the world, namely CPV-2a, CPV-2b, and CPV-2c. The ability of the current vaccines containing either original CPV-2 type or CPV-2b variant to cross protect the heterologous variants has been well demonstrated in laboratory studies, despite some concerns regarding the vaccine efficacy against the emerging variants. Vanguard^®, a series of multivalent vaccines, has been in the market for a considerable period of time and demonstrated to provide efficacy against all three types of CPV variants CPV-2a, CPV-2b, and CPV-2c. The purpose of this study was to evaluate the ability of the recently registered Vanguard C4 vaccine to induce cross-neutralizing antibodies against the Australian isolates of CPV-2a, CPV-2b, and CPV-2c variants. Blood samples collected from dogs vaccinated with Vanguard C4 were analyzed by virus neutralizing assays developed for each of three CPV variants. The results of the study demonstrated that Vanguard vaccine induced cross-neutralizing antibodies against the Australian isolates of CPV-2a, CPV-2b, and CPV-2c, thus offering cross protection against all three Australian CPV variants.

Genetic diversity of canine parvovirus variants circulating in Nigeria

Canine parvovirus (CPV) is a fast-evolving single-stranded DNA virus that causes severe and fatal gastrointestinal disease in dogs. Lately, several mutations affecting viral protein (VP) capsid resulting in highly pathogenic variants with distinctive immunological and clinicopathological characteristics abound. This study involved screening stools of 44 randomly selected clinical cases of canine gastroenteritis from 4 cities (Ibadan, Jos, Makurdi, and Zaria) in Nigeria for CPV antigen using an on-the-spot immunoassay test kit, as well as, molecular detection of viral nucleic acid by polymerase chain reaction. Subsequently, nucleic acid sequencing of 1195-bp amplicons encompassing the VP2 encoding region was done. The resultant 40 high-quality amino acid sequences obtained were analysed for the identification and grouping of the viruses into their discrete variants - CPV-2a, CPV-2b, or CPV-2c, using key amino acids substitutions - Asn, Asp, or Glu respectively at position 426 of the VP2 gene. One-third (11/40; 27.5%) of the analysed sequences were identified as CPV-2a and two-third (29/40; 72.5%) as CPV-2c. The original CPV and CPV-2b were not detected. Also, the "new CPV-2a variant" with mutation S297A identified had two additional mutations (Y324I and T440A) associated with selective pressure and vaccination failure in their sequences. Similarly, unique CPV-2c mutants carrying genetic markers (S297A, Y324I, and Q370R) that are highly related to CPVs of Asian origin were observed. These findings revealed a high level of divergence of existing CPVs in circulation; suggesting that CPV is rapidly evolving in Nigeria lately.

Molecular Characteristics of Carnivore protoparvovirus 1 with High Sequence Similarity between Wild and Domestic Carnivores in Taiwan

Carnivore protoparvovirus 1 (CPPV-1) is a DNA virus causing gastrointestinal disease and immunosuppression in various terrestrial carnivores. Domestic dogs and cats are considered the primary CPPV-1 reservoirs. The habitat overlap of wild carnivores and free-roaming dogs increases the threat of CPPV-1 transmission between them. This study explored the CPPV-1 distribution among wild carnivores in Taiwan through PCR screening and compared the partial capsid protein (VP2) gene sequences from wild and domestic carnivores. In total, 181 samples were collected from 32 masked palm civets (Paguma larvata), 63 Chinese ferret badgers (Melogale moschata), and 86 crab-eating mongooses (Herpestes urva), from 2015 to 2019 were screened for CPPV-1. The average prevalence of CPPV-1 was 17.7% (32/181), with the highest prevalence in masked palm civets (37.5%). In addition, a masked palm civet was coinfected with two CPPV-1 strains. Among the 33 partial VP2 gene sequences, 23 were identical to the sequences amplified from domestic dogs and cats in Asia, and the remaining 10 were identified for the first time. This study supported the circulation of CPPV-1 strains with the same genomic features as domestic carnivores that are also in wild carnivores from the same environment in Taiwan by molecular data. Therefore, further population control and health management of free-roaming domestic carnivores are recommended.

Molecular characterization of canine parvovirus from domestic dogs in Nigeria: Introduction and spread of a CPV-2c mutant and replacement of older CPV-2a by the "new CPV-2a" strain

Canine parvovirus (CPV) is a contagious and highly pathogenic virus of dogs. After its first report in 1978, the CPV original type (CPV-2) was rapidly and totally replaced by three antigenic variants named CPV-2a, CPV-2b and CPV-2c that circulate in various countries at different frequencies and recently reported in Nigeria. This study describes the molecular characterization of 28 CPV strains in dogs presenting with gastroenteritis in veterinary clinics at Lagos and Ibadan, Nigeria. The results show the predominance (92.8%) of CPV-2a, while CPV-2c was found only in two samples. Phylogenetic analyses revealed that the CPV Nigerian strains were closely related to Asian strains and 26 CPV-2a out of 28 CPV sequences fell into 2 different subclades consistent with predicted amino acid mutations at position 267, 321, 324 and 440. Lys321Asn was evident in all the Nigerian strains whilst Phe267Tyr and Tyr324Ile were observed in 96.4% of the sequences, respectively. Thr440Ala occurred in 89.3% of sequences from this study. The new CPV-2a was predominant and appears to have replaced other CPV-2a strains in South-western Nigeria whilst the CPV-2c strain which is identical to the isolate recently reported in Northern Nigeria, may have been introduced in this country at the time of this study. Monitoring virus epidemiology is important to better understand the dynamics of CPV evolution and the eventual need to change or improve existing vaccination strategies.

New genotype classification and molecular characterization of canine and feline parvoviruses

Background

Canine parvovirus (CPV) and feline panleukopenia (FPV) cause severe intestinal disease and leukopenia.

Objectives

In Korea, there have been a few studies on Korean FPV and CPV-2 strains. We attempted to investigate several genetic properties of FPV and CPV-2.

Methods

Several FPV and CPV sequences from around world were analyzed by Bayesian phylo-geographical analysis.

Results

The parvoviruses strains were newly classified into FPV, CPV 2-I, CPV 2-II, and CPV 2-III genotypes. In the strains isolated in this study, Gigucheon, Rara and Jun belong to the FPV, while Rachi strain belong to CPV 2-III. With respect to CPV type 2, the new genotypes are inconsistent with the previous genotype classifications (CPV-2a, -2b, and -2c). The root of CPV-I strains were inferred to be originated from a USA strain, while the CPV-II and III were derived from Italy strains that originated in the USA. Based on VP2 protein analysis, CPV 2-I included CPV-2a-like isolates only, as differentiated by the change in residue S297A/N. Almost CPV-2a isolates were classified into CPV 2-III, and a large portion of CPV-2c isolates was classified into CPV 2-II. Two residue substitutions F267Y and Y324I of the VP2 protein were characterized in the isolates of CPV 2-III only.

Conclusions

We provided an updated insight on FPV and CPV-2 genotypes by molecular-based and our findings demonstrate the genetic characterization according to the new genotypes.

Molecular characteristics of the capsid protein VP2 gene of canine parvovirus type 2 amplified from raccoon dogs in Hebei province, China

Canine parvovirus type 2 (CPV-2) is currently circulating in domestic and wild animals, but our knowledge about CPV-2 infections in raccoon dogs is limited. In this study, VP2 gene sequences of CPV-2 were amplified from rectal swabs of 14 diarrhetic raccoon dogs (Nyctereutes procyonoides) in Hebei province, China, in 2016 and 2017. Phylogenetic analysis of the VP2 gene sequences revealed that most of these sequences (11 of 14) belonged to the same subclade as raccoon dog strain CPV-2/Raccoon_Dog/China/DP-1/16 isolated from Shandong province in 2016. A comparison of deduced amino acid sequences revealed presence of the substitutions S297A and S27T in 11 of those 14 sequences. I418T was observed in a minority of the sequences (4 of 14). In addition, A300D and T301I, P13S and I219V, and N419K were found in three of the sequences. This study shows that CPV-2 strains with different substitutions in their VP2 amino acid sequences were spreading among raccoon dogs in Hebei during 2016 and 2017 and suggests that further studies are needed to monitor the distribution of these strains in China.

Phylogenetic, Evolutionary and Structural Analysis of Canine Parvovirus (CPV-2) Antigenic Variants Circulating in Colombia

Canine parvovirus (CPV-2) is the causative agent of haemorrhagic gastroenteritis in canids. Three antigenic variants—CPV-2a, CPV-2b and CPV-2c—have been described, which are determined by variations at residue 426 of the VP2 capsid protein. In Colombia, the CPV-2a and CPV-2b antigenic variants have previously been reported through partial VP2 sequencing. Mutations at residues Asn428Asp and Ala514Ser of variant CPV-2a were detected, implying the appearance of a possible new CPV-2a variant in Colombia. The purpose of the present study was to characterise the full VP2 capsid protein in samples from Antioquia, Colombia. We conducted a cross-sectional study with 56 stool samples from dogs showing clinical symptoms of parvoviral disease. Following DNA extraction from the samples, VP2 amplification was performed using PCR and positive samples were sequenced. Sequence and phylogenetic analyses were performed by comparison with the VP2 gene sequences of the different CPV-2 worldwide. VP2 was amplified in 51.8% of the analysed samples. Sequencing and sequence alignment showed that 93.1% of the amplified samples belonged to the new CPV-2a antigenic variant previously. Analysing the amino acid sequences revealed that all CPV-2a contain Ala297Asn mutations, which are related to the South America I clade, and the Ala514Ser mutation, which allows characterization as a new CPV-2a sub-variant. The Colombian CPV-2b variant presented Phe267Tyr, Tyr324Ile and Thr440Ala, which are related to the Asia-I clade variants. The CPV-2c was not detected in the samples. In conclusion, two antigenic CPV-2 variants of two geographically distant origins are circulating in Colombia. It is crucial to continue characterising CPV-2 to elucidate the molecular dynamics of the virus and to detect new CPV-2 variants that could be becoming highly prevalent in the region.

Genetic characterization of canine parvovirus type 2c from domestic dogs in Korea

Canine parvovirus type 2 (CPV‐2) is an aetiological agent that causes acute haemorrhagic enteritis and fatal myocarditis in dogs. Since CPV‐2 first emerged in the late 1970s, its rapid evolution has resulted in three antigenic variants: CPV‐2a, CPV‐2b and CPV‐2c. Here, we report, for the first time in Korea, two cases of CPV‐2c infection in two dogs with severe diarrhoea. The complete open reading frame (4,269nt) of CPV‐2, encoding both non‐structural (NS) and structural (VP) proteins, was sequenced. Based on the amino acid Gln present at residue 426 of the VP2 gene, these strains were typed as CPV‐2c, and were named Korea CPV‐2c_1 and Korea CPV‐2c_2. These strains shared 99.48% reciprocal nucleotide sequence identity and had the highest nucleotide identity (99.77%–99.34%) with Asian CPV strains isolated in China, Italy (found in a dog imported from Thailand), and Vietnam from 2013 to 2017. Phylogenetic analysis based on the non‐structural (NS1) and capsid (VP2) genes revealed that Korean CPV‐2c strains clustered closely to Asian CPV strains, and separately from strains isolated in Europe, South America and North America. Amino acid changes never reported before were observed in NS1 (Thr70Pro, Cys287Tyr), VP1 (Lys17Arg, Phe33Leu) and VP2 (Gln365His, Ala516Val). Additional observed mutations, including Phe267Tyr, Tyr324Ile and Gln370Arg, have been previously reported in the recent CPV‐2c strains with Asian origins. These results suggest that the Korean CPV‐2c strains were potentially introduced via neighbouring Asian countries.

Evidence of CPV2c introgression into Croatia and novel insights into phylogeny and cell tropism

Canine parvovirus type 2 (CPV2) emerged for the first time in 1978 and evolved into two antigenic variants CPV2a and CPV2b and the third new antigenic variant CPV2c reported in 2000 in Italy. During 2014 unexplained outbreaks of gastroenteritis were observed in kennels where an extensive vaccination program was ongoing and where vaccinated animals showed pathologic lesions consistent with typical parvovirosis. The aim of this study was to investigate whether CPV2 could have played a role in the emergence of these cases and to evaluate genetic or pathological specificities of the virus and the disease. Using PCR and phylogenetic analysis we showed that the CPV2c variant is circulating in Croatia and is in close relationships with isolates from North and South America. Histopathological lesions and cell tropism that are known for CPV2 we are reporting the identification of the virus in glial cells and ovaries. It seems that evolution of CPV and CPV2a-c and adaptation to dogs are two independent events. Croatian isolates had specific and some unique amino acid mutations under positive selection. The effect of the alterations on the immunoglobulin binding cannot be excluded.

Molecular epidemiology of canine parvovirus type 2 in Italy from 1994 to 2017: recurrence of the CPV-2b variant

Background

Canine parvovirus type 2 (CPV-2) is the most important enteric virus infecting canids. It is a rapidly evolving virus; after its emergence in the 1970s, new antigenic variants (called CPV-2a, 2b and 2c) emerged and replaced the original antigenic type. The three antigenic variants are globally distributed with different frequencies and levels of genetic variability. This study focused on VP2 gene sequence analysis and the phylodynamics of CPV-2 which were detected in 123 dogs showing clinical signs of gastroenteritis collected in Italy from 1994 to 2017.

Results

For the most part, the sick dogs were young, and a third of them (32.5%) had been vaccinated. No statistical association was found between the CPV-2 antigenic variants, and sex, age, breed and vaccination status. Sequence analysis showed that all three antigenic types circulated in Italy; the CPV-2a type was the prominent genotype, followed by CPV-2c and CPV-2b, with notable differences regarding regional bases and significant fluctuations over time. Nucleotide sequence data showed high genetic heterogeneity with 67 nucleotide sequence types (ntSTs) identified, corresponding to 21 amino acid sequence types (aaSTs). The aaSTs and ntSTs obtained were distributed differently among the three CPV-2 antigenic variants: CPV-2a grouped 12/21 (57.1%) aaSTs and 41/67 (61.2%) ntSTs; CPV-2b grouped 5/21 (23.8%) aaSTs and 6/67 (8.9%) ntSTs, and CPV-2c grouped 4/21 (19.1%) aaSTs and 20/67 (29.9%) ntSTs. Canine parvovirus 2a was characterised by the highest genetic variability while CPV-2c was characterised by notable stability with a predominant amino acid profile during the entire sampling time. Canine parvovirus 2b re-emerged in recent years, showing a new and distinctive amino acid profile of the VP2 protein.

Conclusions

The findings of the present study provided new insights regarding the phylodynamics and evolution of CPV-2 in Italy, pointing out notable differences at the local level in the distribution of the CPV-2 variants and the selection of genetic subtypes. The evolution of CPV-2 has raised questions regarding the efficacy of vaccination; therefore, continuous monitoring regarding the evolution and spread of new CPV-2 variants should be a key aim of ongoing research.

Species diversity of fecal microbial flora in Canis lupus familiaris infected with canine parvovirus

Parvovirosis is a highly contagious disease in dogs, often causing acute hemorrhagic enteritis and altering the intestinal microflora. In this study, real-time PCR was used to detect the viral copy numbers in dogs diagnosed with the disease. Hematological and hemobiochemical parameters were also determined. The species and abundances of the fecal microbial flora in both sick and healthy dogs were determined and compared via metagenomic sequencing. The viral copy numbers in the sick dogs were infected with little difference in the positive samples. The blood coagulation time was significantly shorter and the number of white blood cells was significantly greater in the sick dogs. The serum calcium content was slightly increased and the phosphorus content was reduced in the sick dogs. The LDH and CK activities were significantly elevated in the sick dogs. Metagenomic sequencing and analysis revealed relatively more Escherichia, Lachnoclostridium, gnavus group (Ruminococcus), and uncultured_bacterium_f_lachnospiraceae in the infected dogs, whereas the abundance of Collinsella was relatively reduced. Alloprevotella and Sutterella were absent among the fecal microorganisms of the infected dogs. The relative abundances of Romboutsia, Erysipelatoclostridium, Anaerotruncus, and Blautia were significantly increased in the infected dogs. Functional analysis of the metagenomes of the samples indicated a significant enrichment of the 'replication, recombination and repair', 'nucleotide transport and metabolism', 'transcription', and 'defense metabolism' functions in the fecal microbial flora of the infected dogs. In summary, this study provides a scientific theoretical basis for preventing and controlling diarrhea caused by the canine parvovirus.

Spreading of canine parvovirus type 2c mutants of Asian origin in southern Italy

Canine parvovirus type 2 (CPV‐2) emerged as dog pathogen in the late 1970s, causing severe and often fatal epizootics of gastroenteritis in the canine population worldwide. Although to date CPV‐2 is circulating in all continents, most of the current studies have analysed the amino acid changes accounted in the VP2 gene sequence, with limited information on virus introductions from other countries. The aim of this study was to analyse the genetic features of CPV‐2c strains currently spreading in Italy. Swabs and tissue samples were collected from dogs suspected of CPV infection. The nearly complete genome sequence from the CPV‐positive samples was obtained. The co‐circulation of two different but related CPV‐2c strains, with amino acid changes characteristic of CPV strains of Asian origin (NS1: 60V, 544F, 545F, 630P – NS2: 60V, 151N, 152V ‐ VP2: 5A/G, 267Y, 297A, 324I, 370R), were observed. The phylogenetic analyses inferred from the NS1 and VP2 gene sequences confirmed the relationship with Asian CPV‐2c strains. This study reports the spread of novel CPV‐2c mutants in Italy and supports further studies to evaluate the coexistence of genetically divergent CPV strains in the same geographical environment.

Genome sequence characterization of canine parvoviruses prevalent in the Sichuan province of China

Canine parvovirus 2 (CPV-2) infection is responsible for large numbers of animal deaths worldwide and is one of the most dangerous infectious diseases in young puppies. Twenty-four rectal swabs were collected from dogs with clinical signs of vomiting and haemorrhagic diarrhoea and were initially verified to be infected with CPV-2 using colloidal gold test strips. From the 24 CPV-positive samples, complete genome of 5050-5054 nucleotides was sequenced with a next-generation sequencing platform. Characteristics of the Open Reading Frames from different CPV-2 strains detected in this study were analyzed. Several VP2 point mutations were discovered, and demonstrated the co-circulation of new CPV-2a, new CPV-2b and CPV-2c in Sichuan province of China. The analysis results of the Chinese CPV-2 retrieved from the NCBI nucleotide, showed that new CPV-2a has become the predominant variant in some provinces of China. Phylogenetic analysis of global VP2 and NS1 nucleotide sequences revealed certain correlations among geographical regions, types and circulating time, which lays the foundation for further research concerning the epidemiology, genetic variation, vaccination and molecular evolutionary relationships of the CPV-2 identified at different times and from different regions.

Molecular typing of a novel canine parvovirus type 2a mutant circulating in Italy

Canine parvovirus (CPV) is the etiological agent of a severe viral disease of dogs. After its emergence in late 1970s, the CPV original type (CPV-2) was rapidly and totally replaced by three antigenic variants named CPV-2a, CPV-2b and CPV-2c. CPV has an evolutionary rate nearest to those of RNA viruses, with consequences on disease diagnosis and epidemiology. This paper reports the molecular characterization of eight CPV-2a strains collected from dogs in Italy in 2016-2017. Genetic analysis was conducted on a CPV genomic region encompassing both open reading frames (ORFs) encoding for nonstructural (NS1-NS2) and structural proteins (VP1-VP2). Sequence analysis indicates new and unreported sequence changes, mainly affecting the VP2 gene, which included the mutation Tyr324Leu. This study represents the first evidence of a new CPV-2a mutant (VP2 324Leu) and illustrates the importance of a continuous molecular survey in order to obtain more information on effective spread of new CPV mutants.

Designing Two Individual AcMNPV Polyhedrin-Plus Bac-to-Bac Expression System in order to Express GFP and CPV-VP2 in Insect Cells

Background: The importance of viral protein-2 (VP2) of canine parvovirus (CPV) in binding to human cancer cells, production of veterinary vaccines and diagnostic kits has motivated several researches on producing this protein. Objectives: Our purpose was to construct recombinant bacmid shuttle vectors expressing VP2 of CPV using Bac-to-Bac baculoviral expression system. Materials and Methods: Mini-Tn7 transposones engineered in pFastBac1 donor vectors were used to construct expression cassettes of GFP and CPV-VP2. The plasmids were transferred into E. coli DH₁₀Bac competent cells. Site-specific transposition of the genes into bacmid was accomplished using helper plasmid. Occurrence of Transposition was confirmed via PCR using specific primers and PUC/M₁₃ universal primers. The recombinant bacmid DNAs were transfected into Sf9 cells using cationic lipids to generate new recombinant baculoviruses expressing GFP and CPV-VP2. GFP and VP2 expressions were evaluated by fluorescence microscopy and western analysis, respectively. Results: Cloning, subcloning and recombination processes of both GFP and VP2 were accomplished and verified. Accuracy of transfection process was confirmed by GFP fluorescence microscopy.VP2 expression was verified by SDS-PAGE and western analysis. Conclusions: Two Bac-to-Bac expression systems were designed to produce recombinant VP2 and GFP in insect cells.

Phylodynamic and Genetic Diversity of Canine Parvovirus Type 2c in Taiwan

Canine parvovirus type 2c (CPV-2c) emerged in 2000 and is known for causing a more severe disease than other CPV-2 variants in puppies. In 2015, the emerging CPV-2c variant was isolated in Taiwan and it subsequently became the predominant variant. To trace the evolution of Taiwanese CPV-2c, we compared complete VP2 genes of CPV-2c from Taiwan and sequences obtained from GenBank. The evolutionary rate of CPV-2c was estimated to be 4.586 × 10⁻⁴ substitutions per site per year (95% highest posterior density (HPD) was 3.284–6.076 × 10⁻⁴). The time to the most recent common ancestor (TMRCA) dated to 1990 (95% HPD: 1984–1996) and 2011 (95% HPD: 2010–2013) for the CPV-2c variant and Taiwanese isolates, respectively. The CPV-2c variant isolated from Taiwan was clustered with CPV-2c from China. This phylogenetic clade began to branch off in approximately 2010 (95% HPD was 3.823–6.497). Notably, two unique mutations of Taiwanese CPV-2c were found, Q383R and P410L. In summary, this is the first report on the genome evolution of CPV-2c in Taiwan, revealing that this CPV-2c variant shares a common evolutionary origin with strains from China. The demographic history inferred by the Bayesian skyline plot showed that the effective population of CPV-2c increased until 2006 and then slowly declined until 2011.

Introduction of Asian canine parvovirus in Europe through dog importation

Canine parvovirus (CPV) is an important infectious agent of domestic and wild carnivores, responsible for severe and often fatal haemorrhagic gastroenteritis and leukopenia. This paper reports the genomic characterization of a CPV strain collected from a dog recently imported to Italy from Thailand. The virus was detected in all tissue samples collected. The whole genome encompassing the two open reading frames encoding for non‐structural (NS1/NS2) and structural (VP1/VP2) proteins was amplified and sequenced. On the basis of genetic analysis of the VP2 gene, the isolate was characterized as CPV‐2c, but it presented genetic signatures typical of Asian strains. Sequence analysis revealed the presence of amino acid changes never observed in European CPV‐2c strains (NS1: Ile60Val, Tyr544Phe, Glu545Val, Leu630Pro; VP2: Ala5Gly, Phe267Tyr, Tyr324Ile, Gln370Arg). By phylogenetic analysis of full‐length VP2 gene, the analysed strain clustered together with Asian viruses. Therefore, a possible introduction of the virus from Asia through the imported dog was suggested, thus confirming the important role of movement of dogs in the global spread of viruses. In addition, full‐length genome analysis could help better trace the spread of canine viruses through different continents.

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.

Molecular characterization of canine parvovirus in Vientiane, Laos

The global emergence of canine parvovirus type 2c (CPV-2c) has been well documented. In the present study, 139 rectal swab samples collected from diarrheic dogs living in Vientiane, Laos, in 2016 were tested for the presence of the canine parvovirus (CPV) VP2 gene by PCR. The results showed that 82.73% (115/139) of dogs were CPV positive by PCR. The partial VP2 gene was sequenced in 94 of the positive samples; 91 samples belonged to CPV-2c (426Glu) subtype, while 3 samples belonged to the CPV-2a (426Asn) subtype. Notably, phylogenetic analysis of amino acid sequences revealed a close relationship between Laotian isolates and novel Chinese CPV-2c isolates. In Laotian CPV isolates, aligned protein sequences indicated a high rate of residue substitutions at positions 305, 324, 345, 370, 375, and 426 in the GH loop. The mutation at residue 370 (Q370R), a single mutation, was characterized as a unique mutant residue specific to the Laotian CPV-2c variant.

Identification of a novel canine parvovirus type 2c in Taiwan

Background

Taiwan has been considered free from canine parvovirus type 2c (CPV-2c) based on the last report of canine parvovirus type 2 (CPV-2) surveillance. However, since January 2015, the first report of CPV-2c in a puppy has occurred in Taiwan. There is currently limited information about the CPV-2c variant in Taiwan. In the present study, we characterized the previously unidentified CPV-2c variant and investigated the distribution of CPV-2 variants in Taiwan.

Methods

During January 2014 to April 2016, fecal or rectal swab samples from 99 dogs with suspected CPV-2 infection in Taiwan were collected. Eighty-eight were identified as being either CPV-2a, −2b or -2c variants positive by real-time PCR and sequence analysis.

Results

Sequence analysis of the 88 isolates confirmed CPV-2c as the dominant variant (54.6 %), followed by CPV-2b (26.1 %) and CPV-2a (19.3 %). Phylogenetic analysis demonstrated that the recent CPV-2c variants are similar to the Chinese CPV-2c strain but can be considered as novel Asian CPV-2c isolates.

Conclusion

The present study provides evidence for the existence of a novel CPV-2c variant in Taiwan.

Electronic supplementary material

The online version of this article (doi:10.1186/s12985-016-0620-5) contains supplementary material, which is available to authorized users.

Seroprevalence of Canine Parvovirus in Dogs in Lusaka District, Zambia

Canine parvovirus (CPV) enteritis is a highly contagious enteric disease of young dogs. Limited studies have been done in Zambia to investigate the prevalence of CPV in dogs. Blood was collected from dogs from three veterinary clinics (clinic samples, n = 174) and one township of Lusaka (field samples, n = 56). Each dog's age, sex, breed, and vaccination status were recorded. A haemagglutination assay using pig erythrocytes and modified live parvovirus vaccine as the antigen was used. Antibodies to CPV were detected in 100% of dogs (unvaccinated or vaccinated). The titres ranged from 160 to 10240 with a median of 1280. Vaccinated dogs had significantly higher antibody titres compared to unvaccinated (p < 0.001). There was a significant difference in titres of clinic samples compared to field samples (p < 0.0001) but not within breed (p = 0.098) or sex (p = 0.572). Multiple regression analysis showed that only age and vaccination status were significant predictors of antibody titres. The presence of antibody in all dogs suggests that the CPV infection is ubiquitous and the disease is endemic, hence the need for research to determine the protection conferred by vaccination and natural exposure to the virus under local conditions.

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.

Phylogenetic characterization of Canine Parvovirus VP2 partial sequences from symptomatic dogs samples

The aim of the present study was to detect canine parvovirus (CPV) from faecal samples of clinically ill domestic dogs by polymerase chain reaction (PCR) followed by VP2 gene partial sequencing and molecular characterization of circulating strains in Lithuania. Eleven clinically and antigen-tested positive dog faecal samples, collected during the period of 2014-2015, were investigated by using PCR. The phylogenetic investigations indicated that the Lithuanian CPV VP2 partial sequences (3025-3706 cds) were closely related and showed 99.0-99.9% identity. All Lithuanian sequences were associated with one phylogroup, but grouped in different clusters. Ten of investigated Lithuanian CPV VP2 sequences were closely associated with CPV 2a antigenic variant (99.4% nt identity). Five CPV VP2 sequences from Lithuania were related to CPV-2a, but were rather divergent (6.8 nt differences). Only one CPV VP2 sequence from Lithuania was associated (99.3% nt identity) with CPV-2b VP2 sequences from France, Italy, USA and Korea. The four of eleven investigated Lithuanian dogs with CPV infection symptoms were vaccinated with CPV-2 vaccine, but their VP2 sequences were phylogenetically distantly associated with CPV vaccine strains VP2 sequences (11.5-15.8 nt differences). Ten Lithuanian CPV VP2 sequences had monophyletic relations among the close geographically associated samples, but five of them were rather divergent (1.0% less sequence similarity). The one Lithuanian CPV VP2 sequence was closely related with CPV-2b antigenic variant. All the Lithuanian CPV VP2 partial sequences were conservative and phylogenetically low associated with most commonly used CPV vaccine strains.

Genotyping of Canine parvovirus in western Mexico

Canine parvovirus (CPV) is one of the most common infectious agents related to high morbidity rates in dogs. In addition, the virus is associated with severe gastroenteritis, diarrhea, and vomiting, resulting in high death rates, especially in puppies and nonvaccinated dogs. To date, there are 3 variants of the virus (CPV-2a, CPV-2b, and CPV-2c) circulating worldwide. In Mexico, reports describing the viral variants circulating in dog populations are lacking. In response to this deficiency, a total of 41 fecal samples of suspected dogs were collected from October 2013 through April 2014 in the Veterinary Hospital of the University of Guadalajara in western Mexico. From these, 24 samples resulted positive by polymerase chain reaction, and the viral variant was determined by restriction fragment length polymorphism. Five positive diagnosed samples were selected for partial sequencing of the vp2 gene and codon analysis. The results demonstrated that the current dominant viral variant in Mexico is CPV-2c. The current study describes the genotyping of CPV strains, providing valuable evidence of the dominant frequency of this virus in a dog population from western Mexico.

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.

Molecular epidemiological and phylogenetic analyses of canine parvovirus in domestic dogs and cats in Beijing, 2010-2013

Fifty-five samples (15.62%) collected from dogs and cats were identified as canine parvovirus (CPV) infection in Beijing during 2010-2013. The nucleotide identities and aa similarities were 98.2-100% and 97.7-100%, respectively, when compared with the reference isolates. Also, several synonymous and non-synonymous mutations were also recorded for the first time. New CPV-2a was dominant, accounting for 90.90% of the samples. Two of the 16 samples collected from cats were identified as new CPV-2a (12.5%), showing nucleotide identities of 100% with those from dogs. Twelve samples (15.78%) collected from completely immunized dogs were found to be new CPV-2a, which means CPV-2 vaccines may not provide sufficient protection for the epidemic strains.

First isolation of new canine parvovirus 2a from Tibetan mastiff and global analysis of the full-length VP2 gene of canine parvoviruses 2 in China

Canine parvovirus 2 (CPV-2) was first identified in 1978, and is responsible for classic parvoviral enteritis. Despite the widespread vaccination of domestic carnivores, CPVs have remained important pathogens of domestic and wild carnivores. In this study, we isolated CPV-2 from Tibetan mastiffs and performed a global analysis of the complete VP2 gene sequences of CPV-2 strains in China. Six isolates were typed as new CPV-2a, according to key amino acid positions. On a phylogenetic tree, these six sequences formed a distinct clade. Five isolates occurred on the same branch as KF785794 from China and GQ379049 from Thailand; CPV-LS-ZA1 formed a separate subgroup with FJ435347 from China. One hundred ninety-eight sequences from various parts of China and the six sequences isolated here formed seven distinct clusters, indicating the high diversity of CPVs in China. Of 204 VP2 sequences, 183 (91.04%) encoded the mutation Ser297Ala, regardless of the antigenic type, implying that most Chinese CPV-2 strains contain the VP2 mutation Ser297Ala. However, the biological significance of this change from prototype CPV-2a/2b to new CPV-2a/2b types remains unclear. This study is the first to isolate new CPV-2a from the Tibetan mastiff. Our data show that new CPV-2a/2b variants are now circulating in China.

Genetic characterization of type 2a canine parvoviruses from Taiwan reveals the emergence of an Ile324 mutation in VP2

Background

Canine parvovirus 2 (CPV 2) is a major infectious cause of mortality in puppies. The characteristic symptom of CPV 2 disease is intestinal hemorrhage with severe bloody diarrhea. Soon after CPV was first recognized in the late 1970s, the original virus, CPV 2, was replaced in the canine population by strains carrying minor antigenic variants (termed 2a, 2b, and 2c) of the VP2 gene that could be distinguished using monoclonal antibodies and molecular analyses. Here, we provide an updated molecular characterization of the CPV 2 circulating in Taiwan.

Methods

In this study, 28 isolates of CPV 2 from 144 dogs with suspected CPV infection were obtained from northern, central, and southern Taiwan from 2008 to 2012 and screened by PCR. The 28 isolates were sequenced, and a phylogenetic analysis of the VP2 gene was performed.

Results

Of the 28 Taiwanese CPV 2 isolates, 15 were identified as new CPV 2a, and 13 were identified as new CPV 2b. Compared to the reference CPV 2a, all 15 of the CPV 2a sequences collected in this study contain an Ile324 mutation caused by a TAT to ATT mutation at nucleotides 970–972 of the VP2 gene.

Conclusion

Our VP2 sequence data revealed that both types are currently prevalent CPV 2 field strains circulating in Taiwan, and a unique Ile324 VP2 mutation was found in our Taiwanese CPV 2a isolates and recent Asian isolates. CPV 2c was not observed in this study.

Identification of canine parvovirus with the Q370R point mutation in the VP2 gene from a giant panda (Ailuropoda melanoleuca)

Background

In this study, we sequenced and phylogenetic analyses of the VP2 genes from twelve canine parvovirus (CPV) strains obtained from eleven domestic dogs and a giant panda (Ailuropoda melanoleuca) in China. A novel canine parvovirus (CPV) was detected from the giant panda in China.

Results

Nucleotide and phylogenetic analysis of the capsid protein VP2 gene classified the CPV as a new CPV-2a type. Substitution of Gln for Arg at the conserved 370 residue in CPV presents an unusual variation in the new CPV-2a amino acid sequence of the giant panda and is further evidence for the continuing evolution of the virus.

Conclusions

These findings extend the knowledge on CPV molecular epidemiology of particular relevance to wild carnivores.

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.