Cloning And Sequence Analysis Of Open Reading Frames 5 To 7 And Research On Molecular Epidemiology Survey Of Porcine Reproductive And Respiratory Syndrome Virus In Guangxi

In this study, samples with porcine reproductive and respiratory syndrome virus (PRRSV) from different places of Guangxi were detected. It was found that there was PRRSV in semen, aborted fetus, lymph node and kidney. It showed that PRRSV may exist in other tissues of swines. Cloning and sequence analysis of open reading frame (ORF) 5 gene of semen and aborted fetus, showed that homology of nucleotide and amino acid got to 100%. It fartherly proved that PRRS may vertically transmit through semen infected by PRRSV and caused reproductive failure.12 of ORF 5 genes, 8 of ORF6 genes, 5 of ORF7 genes in 12 positive samples were cloned and sequenced. The results showed that compared with ORF5, ORF6 and ORF7 genes of CH-1a, HB-1, FJ-1, BJ-4, VR-2332, vaccine strains and so on, homology between strains ranged from 87.2-97.3%, 90.1-97.9%, 90.1-98.4% for the nucleic acids, 85.1-96.0%, 92.0-97.1%, 87.9-96.8% at the amino acids level. Compared with LV strain, homology of the strains shared 62.2-64.0%, 68.2-68.8%, 65.6-67.5% for the nucleic acids, 55.7-56.2%, 75.9-78.2%, 55.6-58.9% at the amino acids level. Phylogentic tree indicated that strains of GX belonged to three subgroups (I, II, IV), 12 strains in the study was in II subgroup, there was more distinct in the strain of GXWX, what was related to quasispecises variable strain B2 of America, others were closely related to HB-1 strain, it supposed that there were same origin. Amino acid analysis of GP5 protein showed that they had no relation with vaccine strains, belonging to field strains; except for GXWX, all strains had quasispecises character of...