Detection And Evolution Analysis Of PCV3 In Dogs,Cats And Pigs In Some Areas Of Liaoning Province

Porcine circovirus type 3(PCV3)is the third novel virus in Cycloviridae.It can infringe on the digestive system and respiratory system of dairy piglets,and the reproductive system of sows,cause multisystem inflammation of piglets and reproductive disorders of sows,bring great harm to pig farms,and seriously threaten the development of the industry.Since 2016,PCV3 virus was first found from sows in a pig farm in the United States,including China,South Korea,Japan,Russia,Sweden,Italy,Denmark,Spain and other countries,indicating that PCV3 has been widely prevalent in the world.In addition to PCV3 being detected in pigs,PCV3 virus was also detected in other animal bodies.Regarding the increasing prevalence of PCV3,it is necessary to investigate the prevalence of PCV3 in pigs and pets in this province.Methods: In this study,188 pig tissue samples and canine and cat samples were collected from 2019 to 2020.After nucleic acid extraction,specific PCV3 primers were designed to screen PCR for PCV3 to determine the infection of PCV3 in pigs,cats and dogs.Subsequently,the positive PCR products were sequenced,and MEGA software was aligned to amino acids and nucleotides with 23 PCV3 sequences at home and abroad,and an evolutionary tree was constructed to analyze the evolution and evolution of viruses.Results: A total of 14 PCV3 gene sequences were obtained in Liaoning Province,with a positive rate of 7.45%.Ten samples were detected from Jinzhou,Dalian,Fuxin,Huludao,Tieling and Liaoyang pigs in Liaoning Province,and four were detected from cat samples.Positive was 10.3%(10 / 97)for pigs,16.7%(4 / 24)for cats and 0(0 / 67)for dogs.The PCV3 infection is more severe in the indicated cats,which has not been reported.The obtained sequence was compared with domestic and foreign sequence,with nucleotide identity 98.3-100% and amino acid identity 99.2-100%.Five sequences were PCV3 b subtypes,and nine sequences were PCV3 a isoforms.This indicates that subtype 3a is still the main epidemic type.There are 15 amino acid mutation sites in ORF2 at positions24,27,57,77 and 150;position 11 in Malaysia and the rest in domestic epidemic strains.Conclusion: This study has enriched the PCV3 research data in the province.The detection of higher PCV3 infection in cat samples for the first time provides evidence for transmission trends across species.