Serological Investigation Of PRRS And Analysis On GP5 Gene Inthree Strains PRRSV In Yunxiao

Porcine reproductive and respiratory syndrome(PRRS)is one of the most important diseases of pig industry,which brings huge economic losses to the world every year.The porcine reproductive and respiratory syndrome can lead to the symptoms of burnout,anorexia fever,preterm birth,abortion,fetal death,mummies and weak off spring,and weaken the immune regulation.Yunxiao is a big pig county in Zhangzhou City,The epidemic of PRRS also could pose a severe challenge to the pig raising industry in Yunxiao.Through the PRRS antibody detection and antigen detection,the epidemic and genetic variation of PRRSV in Yunxiao are analyzed.It provides a theoretical basis for the prevention and control of PRRSV in Yunxiao.A total of 3865 serum samples of pigs that were immunized with PRRS vaccine were collected in Yunxiao county from 2013 to 2017.The serological qualification rate of PRRSV was investigated in different years,seasons and so on.From the results of serological investigation of PRRS in Yunxiao county,we can find that the immune qualification rate of PRRS is good,but PRRS is still found in clinical cases.In order to further understand the occurrence of PRRS in Yunxiao county,three strains of PRRSV were sequenced and the antigenic sites were analyzed.Glycosylation site,phosphorylation site,transmembrane structure and secondary structure were analyzed.The results of this study are as follows:1 The highest qualified rate of serum antibody in pigs was 2013(84.85%),and the lowest was 2014(82.90%)The positive rates of antibodies in different types of farms were different,and the positive rate of antibody was in the order of 87.73%,83.13%,77.50%,respectively.2 Three strains PRRSV are all belong to second gene type,and the homology is between 61.9%and 99.5%.the change phosphorylated tite of FJYX-1 was at 23th?41th amino acid compared with reference strains,the change phosphorylated tite of FJYX-2 was at 23th amino acid compared with reference strains,FJYX-3 strain did not have variation compared with reference strains.The glycosylation site in three strain PRRSV did not have large variation.The amino acid sequences of three PRRSV GP5 proteins were compared with the reference strains.The amino acids locusing at 15th,23th,41th,196th were found changing into proline,serine,arginine in FJYX-1 strain;the amino acids locusing at 23th,151th 196th were found changing into serine,arginine,lysine in FJYX-2 strain.the amino acids locusing at 28th,33th,193th,196th were found changing into Proline,glutamic acid,alanine,histidine in FJYX-3 strain;The predicted results of antigenic peptide showed that there were 7-8 antigenic sites in GP5 protein of these three strains.The FJYX-2 strain had a 143-NFL LDTK-149 antigen peptide more than the other strains.In conclusion,there is no obvious variation in PRRS immunity in Yunxiao county.Compared with reference strain,there is no obvious mutation in glycosylation site,but the phosphorylation site,amino acid site and antigenic peptide segment have some degree of variation.We need to closely monitor the variation of PRRS and provide effective theoretical basis for prevention and control in Yunxiao.