Abstract
BackgroundThe infection in dogs due to canine parvovirus (CPV), is a highly contagious one with high mortality rate. The present study was undertaken for a detailed genetic analysis of partial VP2 gene i.e., 630 bp isolated from rectal swab samples of infected domestic and stray dogs from all areas of district Faisalabad. Monitoring of viruses is important, as continuous prevalence of viral infection might be associated with emergence of new virulent strains.MethodsIn the present study, 40 rectal swab samples were collected from diarrheic dogs from different areas of district Faisalabad, Pakistan, in 2014–15 and screened for the presence of CPV by immunochromatography. Most of these dogs were stray dogs showing symptoms of diarrhea. Viral DNA was isolated and partial VP2 gene was amplified using gene specific primer pair Hfor/Hrev through PCR. Amplified fragments were cloned in pTZ57R/T (Fermentas) and completely sequenced. Sequences were analyzed and assembled by the Lasergene DNA analysis package (v8; DNAStar Inc., Madison, WI, USA).ResultsThe results with immunochromatography showed that 33/40 (82%) of dogs were positive for CPV. We were able to amplify a fragment of 630 bp from 25 samples. In 25 samples the sequences of CPV-2a were detected showing the amino acid substitution Ser297Ala and presence of amino acid (426-Asn) in partial VP2 protein. Interestingly the BLAST analysis showed the of feline panleukopenia virus (FPV) sequences in 3 samples which were already positive for new CPV-2a, with 99% sequence homology to other FPV sequences present in GenBank.ConclusionsPhylogenetic analysis showed clustering of partial CPV-VP-2 gene with viruses from China, India, Japan and Uruguay identifying a new variant, whereas the 3 FPV sequences showed immediate ancestral relationship with viruses from Portugal, South Africa and USA. Interesting observation was that CPV are clustering away from the commercial vaccine strains. In this work we provide a better understanding of CPV prevailing in Pakistan at molecular level. The detection of FPV could be a case of real co-infection or a case of dual presence, due to ingestion of contaminated food.
Highlights
The infection in dogs due to canine parvovirus (CPV), is a highly contagious one with high mortality rate
Canine parvovirus-2 (CPV-2) is a single stranded DNA virus that is the most dreadful enteropathogen causing myocarditis and acute hemorrhagic gastroenteritis in dogs and young pups while Feline panleukopenia is a disease of cats caused by a highly contagious virus i.e., feline panleukopenia virus (FPV) [1]
In this study we have reported phylogenetic and sequence analysis of two viruses i.e., CPV and FPV detected in dogs
Summary
The infection in dogs due to canine parvovirus (CPV), is a highly contagious one with high mortality rate. CPV-2a and CPV-2b divergence occurred from the CPV-2 strain due to changes in 5–6 amino acids in the antigenically important VP2 capsid region and in regaining the ability to infect feline cells in vitro and cats in-vivo again, while providing better adaptation to the canine host. CPV and FPV are two closely related viruses, causing disease in respective hosts, but new variants of CPVs have acquired the feline host range allowing them to infect both cats and dogs [5, 6], whereas the original CPV-2 does not replicate in cats. Amplification of partial VP2 gene and subsequent sequencing of the PCR products, where many important informative amino acids reside, would give definitive antigenic and genetic difference between the original CPV-2, its variants, and the vaccine strains [11]. For the purpose of identification of CPV, there are quite a few published papers where researchers have used partial VP2 gene sequence to report CPV [13, 14]
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