| In this study, in order to find out the genetype of PRRSV in Henan and explore the effect on the immune function of pigs after Porcine reproductive respiratory syndrome (PRRSV) infection between acute PRRSV and modified PRRSV.Three PRRSV isolates named by Hn-1/06 Hn-2/06 and Hn-3/06 which were obtained from Henan Province's differet pig farms A RT-PCR method was used to amplify the complete ORF5 gene of these virus. Identity and variation analysis of ORF5 gene and the deduced amino acid of these isolates with the other seven published PRRSV isolates from different source showed that percent identity of the ORF5 gene and amino acid of these Henan isolates share more than 95.5% identity to each other. Between these Henan isolates and the other America isolates ,the identity ranged from 86.1% to 98.7% respectively, but the Henan isolates and LV have just 53.1% to 54.5% identity. Further comparision of the deduced amino acid sequence of ORF5 gene of Henan isolates with other America isolates indicated that some sites of GP5 have taken into mutation, especially, the 39th deduced amino acid which locates at the neutralizating site of Henan isolates differ from other America isolates.So our results showed that the PRRSV isolates from herds experiencing acute PRRS outbreak in Henan are mutant isolates of America genotype.Twelve 30-day-old pigs were randomly assigned into three groups. At the same time, the pigs in two experimental groups were infected respectively with PRRSV Hn-1 isolate and PRRSV BJ-4 isolate, in the control group, Marc-145 cell was used . some samples from the tissues infected and the samples of serum and lymphocyte were obtained from pigs' bloods of each group on the 0th,5th,11th,18th,30th,40th and 50th day after infection, which were used to test the PRRSV and the content of virus, antibody titer and the content of CD3~+, CD4~+ and CD8~+ T lymphocytes . PRRSV RNA was examined from the samples of leucocyte ,serum , nasal cavity secretion, lung, lymph node,liver and spleen. The content of PRRSV was detected higher from PRRSV Hn-1/06 experiment group than the PRRSV BJ-4 experiment group. And PRRSV Hn-1/06 isolate could cause acute PRRS. By ELISA antibody againt PRRSV N protein detected of PRRSV Hn-1/06 experiment group appear earlier than the other experiment group', and antibody titers of PRRSV Hn-1/06 experiment group was earlier and higher than the PRRSV BJ-4 experiment group.The neutral antibody by cell neutral test which were examined from BJ-4 experiment group after the 30th day Of infection didn't be detected in PRRSV Hn-1 experiment group until the pigs died. By using flow cytometry with double-color-staining method respectively,The content of CD3~+, CD4~+ and CD8~+ T lymphocytes of two experiment groups were detected .before the 2-3th week,the content was all reducing in two experiment groups ,and The ratio of CD4~+/CD8~+ T lymphocytes is significant different between two experiment groups and that of the control group.but, from the 6th to 7th week, the content of CD3~+ ,CD4~+ ,CD8~+ T lymphocytes and the ratio of CD4~+/CD8~+ T lymphocytes of two experiment groups were approaching to those of control group. So, Those implied that during the first2-3 weeks, it is the most dangerous time for those pigs infected by PRRSV,because the neutral antibody had not generated and the cell immunity was restrained in this time. |
