Isolation And Identification Of 10 Strains Of CPV And FPV And Analysis Of Genetic Variation Of NS1 And VP2 Genes

Canine parvovirus(CPV)and Feline panleukopenia virus(FPV)are considered to be one of the most serious viruses endangering dogs and cats,which induce the higher mortality rates,respectively,and the cure rate with drug control is very low.At present,immunization with pentavaccine or hexavaccine of the combination of parvoviruses and other viruses in our country often results in the immune failures.This may be due to the reasons of different regions and virus mutations and so on.The CPV and FPV belong to the parvovirus genus.The age of onset and the clinical symptoms of the two diseases are similar.The frequent occurrence of CPV and FPV disease in clinical practice raises doubts about the immune effects of vaccines and multi-component vaccines,or whether there are variations.In view of this,this study isolated and identified CPV and FPV epidemic strains in Guangdong to provide the basis for further virus research.The isolated FPV and CPV strains were sequenced to analyze the genetic relationship between the two,in order to provide the basis for monitoring the variability and prevalence of FPV and CPV,and to lay a foundation for the development of a universal nucleic acid vaccine for cCPV and FPV.In this experiment,canine and feline parvovirus antigen rapid test strips and PCR method were used to detect fecal samples from dogs and cats suspected of CPV and FPV infection from an animal hospital in Guangzhou.Four cases with positive CPV and six cases with positive FPV were detected;the soak solution of feces was filtered.The virus was isolated using CRFK cells,and it was observed that CRFK cells infected with different strains of virus exhibited lesions such as wiredrawing,atrophy,rounded shape,and falling off at different times.According to the whole genome sequence of the different strains of CPV and FPV collected from GenBank,three pairs of specific primers were designed and synthesized in the conserved region,and the three open reading frames NS1,VP1 and VP2 of the CPV and FPV were amplified.The three genes were amplified from the 10 virus samples and cloned into the pDM19-T vector.After sequencing and splicing,the full-length viral gene sequence of about 4300 bp was obtained.By DNAStar software analysis,the homology of CPV and FPV was above 97.1%.The sporadic point mutations were mainly distributed in the NS1 protein of CPV and FPV.The main differences between the two viruses were concentrated on the VP2 protein,and the 93 rd,103rd,323 rd site of amino acid sequence and the 80 th,546th and 584 th site of amino acid residue determined the host specificity and antigenicity of CPV and FPV.In addition,a comparative analysis of key amino acid sites of CPV VP2 protein revealed that CPV-A,CPV-B,and CPV-D strains belonged to CPV-2a type,and CPV-C strains belonged to CPV-2b type.By analyzing the hydrophilicity and antigenic index of VP2 protein,it was found that the 5 to 45 and 350 to 420 sites of amino acid were high in hydrophilicity and antigenic index,and had a good immunogenicity,which was the primary choice for making vaccines.