Clinical Detection Of Four Viral Swine Diseases And Immunoprotection Of Circovirus Type 2 Vlps In Northern Hunan

To investigate porcine circovirus virus type 2(PCV2);porcine reproductive and respiratory syndrome virus(PRRSV);swine fever virus(CSFV);porcine epidemic diarrhea virus(PEDV)four common virus infection in northern part of hunan province pig level and distribution situation,using PCR and RT-pcr method,in September 2017-July 2018 years from changsha,yiyang and yueyang,changde city of four states 45 pig tested 118 samples of suspected sick pigs,and on the part of the wreath virus type 2 positive samples sequencing and analysis of genetic variation,The virus particles of porcine circovirus type 2 were cross-protected.The results showed that PCV2 infection rate was 42.7%,PRRSV infection rate was 22.9%,CSFV infection rate was 11%,PEDV infection rate was 3%,and the infection rate of circovirus type 2 was the highest.Thirty-one samples were positive for mixed infection of at least two types of viruses,among which circovirus type 2 was the most serious mixed infection with porcine reproductive and respiratory syndrome,reaching 15 cases.In this paper,genetic typing analysis of ORF2 genes in 13 positive samples of porcine circovirus type 2(PCV2)in northern hunan was further carried out.It was found that 3 samples were PCV2 a,5 samples were PCV2 b,and 5 samples were PCV2 d.The results showed that at present,PCV2 in northern hunan was dominated by PCV2 b and PCV2 d genotypes,accompanied by other types,which better understood the prevalence of PCV2 in northern hunan.In order to further study the cross-protection of PCV2 b and PCV2 d,a cross-protection test was designed.In this experiment,female kunming mice were injected with PCV2 b virus-like particles(with adjuvant)or PCV2 d virus-like particles(with adjuvant)and then challenged with PCV2 virus original solution.37 mice were randomly divided into seven groups,quarantine PCV2 poison attack + PCV2 b virus-like particles(including adjuvant)vaccination,PCV2 poison attack + PCV2 d virus-like particles(including adjuvant)vaccination,PCV2 poison attack + PCV2 b virus-like particles(including adjuvant)+ PCV2 d virus-like particles(including adjuvant)vaccines and vaccination,PCV2 poison attack + vaccination PBS,vaccination dose PBS same as blank group,only seven residual poison attack or vaccination spare group.The results showed that both PCV2 b virus particles and PCV2 d virus particles had a good protective effect on their subtypes,and the effect was more obvious when acting together,but the cross-protec-tive effect was not obvious.