The Pathogenic Epidemiology Survey Of Porcine Parvovirus And The Sequence Analysis Of NS1?VP2 Of Porcine Parvovirus Strain

Porcine parvovirus(PPV)is considered to be one of the major causes of reproductive failure in swine.Clinical signs of PPV infection are SMEDI(stillbirth,mummification,embryonic death and infertility).It is brought more serious economic losses to the global swine industry.In recent years,several new parvoviruses have been identified in pigs,namely PPV2 to PPV7.So far,there have been failed to separate from porcine parvoviruses except PPV.The study of novel PPV mainly focus on molecular epidemiology and gene sequences at home and abroad and little is known about the pathogenicity of novel PPV.This study was to investigated the prevalence of the above seven porcine parvoviruses in Hunan province and conducted virus isolation of PPV-positive samples in order to further understand the prevalence and pathogenicity of PPV in our province.The main content is following: 1.The pathogenic epidemiology investigation of PPV and virus isolationIn this study,a pathogenic epidemiological investigation of PPV was performed using PCR for 197 anal swabs from five swine farms,197 nasal swabs from five swine farms,389 serums from nine swine farms,and slaughterhouse finishing pigs collected from 2014 to 2017 were used in the PCR method.The results showed that the positive rate of PPV in anal swabs was 2.5%(5/197),2.0%(4/197)of the nasal swabs,1.0%(4/389)of serums and 22.9%(71/310)of the lungs in slaughter finishing pigs,indicating that PPV was detected in feces,nasal secretions,serum and lung tissues,and the positive rate was extremely high in the lungs.Virus isolation was performed on PPV-positive samples and only 5 PPVs were isolated from the lungs.2.Sequence analysis of NS1 and VP2 isolates of PPVThe 5 strains of PPV isolates isolated from the lungs all had a sequence size of 4435 bp.The nucleotide homology between the isolates was 99.8%-100%,and the amino acid nucleotide homology was 99.8%-100%.The full length of PPV NS1 gene is 1989 bp,which encodes 662 amino acids.The full length of PPV VP2 gene is 1740 bp and encodes 579 amino acids.Nucleotide homology and amino acid homology between the five isolates NS1 and VP2 were all above 97%,demonstrating that the isolates isolated from the lungs were very conservative.It is closest relation between HuN strain and German strain.3.Novel PPV pathogenic epidemiology investigation and virus isolationIn this study,a pathogenic epidemiological investigation of the novel PPV using 154 serum samples from two farms was performed using PCR.The results showed that the detection rate of PPV2 was 29.9%(46/154),14.3%(22/154)for PPV3,1.9%(3/154)for PPV4,8.4%(13/154)for PPV5,was 44.2%(68/154)for PPV6,and 9.1%(14/154)for PPV7.Of these results,.And novel PPV genotype was highly detected in finisher pigs.Among the serum samples,PPV6 and PPV2 were with hghest detection rates.Most of the novel PPVs can be detected as early as 4 weeks of age,and the detection rate of the new PPV is highest in finishing pigs.There was no novel PPVs could be isolation.