Expression or subcellular targeting of virus capsid proteins with cloning genome of a canine parvovirus from China

Whole genome sequence analysis of CPV-2 isolates from 1998 to 2020

Canine parvovirus-2 (CPV-2) is a virus with worldwide spread causing canine gastroenteritis. New strains of this virus have unique characteristics and are resistant to some vaccine strains. Therefore, understanding the root causes of resistance has proven to be of increasing concern to many scientists. This study collected 126 whole genome sequences of CPV-2 subtypes with specific collection dates from the NCBI data bank. The whole genome sequences of CPV-2 collected from different countries were analyzed to detect the new substitutions and update these mutations. The result indicated 12, 7, and 10 mutations in NS1, VP1, and VP2, in that respective order. Moreover, the A5G and Q370R mutations of VP2 are the most common changes in the recent isolates of the CPV-2C subtype, and the new N93K residue of VP2 is speculated to be the cause of vaccine failure. To summarize, the observed mutations, which are increasing over time, causes several changes in viral characteristic. A comprehensive understanding of these mutations can lead us to control potential future epidemics associated with this virus more efficiently.

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.

Isolation of Canine parvovirus with a view to identify the prevalent serotype on the basis of partial sequence analysis

Aim:

The aim of this study was to isolate Canine parvovirus (CPV) from suspected dogs on madin darby canine kidney (MDCK) cell line and its confirmation by polymerase chain reaction (PCR) and nested PCR (NPCR). Further, VP2 gene of the CPV isolates was amplified and sequenced to determine prevailing antigenic type.

Materials and Methods:

A total of 60 rectal swabs were collected from dogs showing signs of gastroenteritis, processed and subjected to isolation in MDCK cell line. The samples showing cytopathic effects (CPE) were confirmed by PCR and NPCR. These samples were subjected to PCR for amplification of VP2 gene of CPV, sequenced and analyzed to study the prevailing antigenic types of CPV.

Results:

Out of the 60 samples subjected to isolation in MDCK cell line five samples showed CPE in the form of rounding of cells, clumping of cells and finally detachment of the cells. When these samples and the two commercially available vaccines were subjected to PCR for amplification of VP2 gene, a 1710 bp product was amplified. The sequence analysis revealed that the vaccines belonged to the CPV-2 type and the samples were of CPV-2b type.

Conclusion:

It can be concluded from the present study that out of a total of 60 samples 5 samples exhibited CPE as observed in MDCK cell line. Sequence analysis of the VP2 gene among the samples and vaccine strains revealed that samples belonged to CPV-2b type and vaccines belonging to CPV-2.

Antigenic typing of canine parvovirus using differential PCR

Canine parvovirus (CPV) is an enteric pathogen causing hemorrhagic enteritis in pups of 3-6 months of age and is mainly transmitted via feco-oral route. In the present study, a total of 85 animals rectal swabs suspected of CPV were tested using a PCR, nested PCR and a newly designed differential PCR. Using PCR 7 (8.23 %) animals were positive whereas 39 (45.88 %) were positive by using nested PCR and 40 (47.05 %) were positive for either one or more than one antigenic types of CPV using differential PCR. Using differential PCR it was found that CPV-2a and CPV-2b were the most prevailing antigenic types. Also it was found that dogs that were vaccinated too yielded positive CPV indicating a possible presence of additional CPV antigenic types. Thus, the primers used in differential PCR can be used in a single PCR reaction to detect various antigenic types of CPV.