| Porcine circovirus 3(PCV3)causes an increased rate of miscarriage in pregnant sows,respiratory disease,diarrhea and exudative dermatitis in piglets.Both Transmissible gastroenteritis virus(TGEV)and Porcine epidemic diarrhea virus(PEDV)are porcine enteric coronaviruses,which can cause dehydration and increase mortality in pigs.After infecting adult pigs with TGEV,they can remain disease-free,remain in a carrier state,and continue to detoxify.The disease is spread due to hog trading and gilt transregional transport processes,which make it more difficult for pig farms to remove TGEV and PEDV.In this study,the prevalence,mainstream genotypes,isolation and identification of PCV3,TGEV and PEDV were studied and discussed.In this study,1040 samples were collected from 9 cities in Shandong Province(Jinan,Qingdao,Zibo,Weifang,Linyi,Liaocheng,Binjiuzhou,Heze,Rizhao),which were tested by PCR.The detection rate of PCV3 was 2.3%(24/1040)and was detected in pigs of different seasons and ages.The detection rate of TGEV was 4.1%(43/1040),mainly in autumn and breeding herd.The PEDV detection rate was 0.2%(3/1040).Among them,one case of mixed infection of PEDV and TGEV was found.The complete genome of PCV3 positive samples was amplified and the complete genome of two PCV3 strains,S19 and BZ-L,were obtained.Based on the complete genome and ORF1 genetic evolutionary trees,S19 and BZ-L belong to PCV3 a genotype and are far genetic proximity each other.The S gene sequence of PEDV positive samples was amplified,and two PEDV S genes were obtained,which were named LC01 and LC02.The genetic evolution tree showed that LC01 and LC02 belonged to the GI-a genotype,and were closely related to the classical vaccine strain CV777 and all belonged to the GI genotype.But LC01 and LC02 were far genetic proximity to the Hubei vaccine strain AJ1102 in the GII subgroup.LC01 and LC02 were analyzed by S protein amino acid homology,and the results showed that the deduced amino acid homology between LC01 and LC02 was 99.9%.Compared with the classical vaccine strain CV777,the deduced amino acid sequence homology was 95.8% and 95.9%;The deduced amino acid homology was 92.7% and 92.8% with Hubei vaccine strain AJ1102,and 99.8% with South Korean vaccine strain DR13-JQ023162.The TGEV positive samples were inoculated into PK-15 cells,and a TGEV strain named SD01 was isolated after passage.No PEDV or PDCo V contamination was found by PCR detection.Cytopathic effects were observed 48 hours after inoculation,and coronal virions were observed by electron microscopy.The complete genome of SD01 was obtained by second-generation sequencing(NGS)technology.Clustal W conducted sequence comparison to evaluate the complete genome of SD01 and 38 reference strains,including S gene,M gene and N gene,as well as non-structural genes ORF1 a and ORF1 b.The results showed that,the strains of the Miller genotype of the SD01 strain are most closely genetic proximity.In conclusion,large-scale pig farms in Shandong Province were infected by PCV3,TGEV and PEDV to varying degrees.This study analyzed the genetic evolution of PCV3,TGEV and PEDV epidemic strains in Shandong Province.The obtained data enriched the epidemiological data of PCV3,TGEV and PEDV in Shandong Province,and provided a certain theoretical basis for the prevention and control of pig disease. |
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