The Effect Of PRRSV-specific Peptides On The Secretion Of IFN-γ And IL-10by Swine Peripheral Blood Lymphocyte After CSF And PRRS Vaccination

Porcine reproductive and respiratory syndrome (PRRS) is a fulminatinginfectious disease which caused by porcine reproductive and respiratory syndromevirus(PRRSV) infection. Now PRRS has become one of the main diseases of largeand small pig farms in our country. PRRSV can destroy the immune system of swineresulting of long-lasting immunosuppression. The coinfection of PRRSV and classswine fever virus（CSFV）will increase the mortality rates and huge economic loses.Cell-mediated immunity of CSFV and PRRSV are interrelated and interact on eachother, but the immunologic effector mechanisms is unclear.In order to detect the influence of PRRSV specific peptide on the secretion ofcytokines, twenty weaned clinical health and PRRSV, CSFV, PCV2, PRV antibodiesnegative piglets were used to detect the changes of IFN-γ and IL-10stimulated byPRRSV specific peptides. Then all the piglets were vaccinated the CSF and PRRSvaccine. At the14th and28th days after PRRS vaccination, we collected bloodsamples from the precava of the pigs respectively to separate PBMCs and the sera.Serum PRRSV and CSFV antibody levels were detected. PBMC were cultured withRPMI1640containing10%calf serum in5%CO2,37℃and the levels of IFN-γ andIL-10secreted by lymphocytes stimulated with PRRSV-GP5（GP5aa96-104）,PRRSV-N-1（N-1aa106-114）and PRRSV-N-2（N-2aa49-57）specific peptide weremeasured by commercial ELISA kits at different time points. And changes ofcytokines in cell culture supernatant were analyzed twice. At the same time, the levelsof CSFV and PRRSV antibodies were detected by ELISA kits. According to thePRRSV and CSFV antibody responsiveness, these pigs were divided into four groups:CSFVab+-PRRSVab+group, CSFVab+-PRRSVab-group, CSFVab--PRRSVab+group and CSFVab--PRRSVab-group. The changes of IFN-γ and IL-10in lymphocyteculture supernatant which stimulate by GP5aa96-104, N-1aa106-114and N-2aa49-57specific peptide, respectively, were analyzed.At the14d after PRRSV vaccination, stimulating the lymphocytes with GP5aa96-104specific peptide at the time cultured24h, the peptide-stimulated secretion ofIFN-γ increased significantly in CSFVab+-PRRSVab-group(P<0.05), CSFVab-groups were not significant difference(P>0.05), the peptide-stimulated secretion ofIL-10reduced significantly in all groups(P<0.05); stimulating the lymphocytes withN-1aa106-114specific peptide, there were no significant difference in the level ofIFN-γ between the peptide-stimulated groups and the control groups when cells werecultured24h in all groups(P>0.05), but the peptide-stimulated secretion of IL-10reduced significantly(P<0.05); stimulating the lymphocytes with N-2aa49-57specificpeptide at the time cultured24h, the peptide-stimulated secretion of IFN-γ increasedsignificantly in CSFVab+-PRRSVab-group(P<0.05)and the level of IL-10werereduced significantly in all groups(P<0.05). Stimulating the lymphocytes with GP5aa96-104specific peptide at the time cultured72h, the level of IFN-γ were notsignificant difference in all groups(P>0.05); stimulating the lymphocytes with N-1aa106-114specific peptide at the time cultured72h, there were no significant differencein the level of IFN-γ in all groups(P>0.05), but the peptide-stimulated secretion ofIL-10reduced significantly(P<0.05); stimulating the lymphocytes with N-2aa49-57specific peptide at the time cultured72h, the peptide-stimulated secretion of IL-10reduced significantly in all groups(P<0.05).At28d after PRRSV vaccination, the peptide-stimulated secretion of IFN-γincreased significantly in CSFVab+-PRRSVab-group at the time cultured24h whenstimulating the lymphocytes with GP5aa96-104specific peptide(P<0.05), the level ofIL-10were not significant difference in all groups(P>0.05); stimulating thelymphocytes with N-1aa106-114specific peptide at the time cultured24h, thepeptide-stimulated secretion of IFN-γ increased significantly in all groups(P<0.05),but the level of IL-10were not significant difference(P>0.05); there were no significant difference in the level of IFN-γ and IL-10in all groups between groupstimulated by N-2aa49-57and the control group when cells cultured24h (P>0.05).Stimulating the lymphocytes with N-1aa106-114specific peptide at the time cultured72h, there were no significant difference in the level of IFN-γ in all groups(P>0.05),the peptide-stimulated secretion of IL-10reduced significantly inCSFVab+-PRRSVab+group and CSFVab+-PRRSVab-group(P<0.05); the level ofIFN-γ were not significant difference in all groups (P>0.05), and thepeptide-stimulated secretion of IL-10reduced significantly in CSFVab--PRRSVab+group which were stimulated with N-2aa49-57specific peptide at the time cultured72h (P<0.05).According to the present results, it could be indicated that the increasing CSFVantibody expression can enhance the tolerance of PRRSV. Good immune status ofCSF can help the GP5aa96-104and N-2aa49-57peptide stimulating lymphocytes tosecret the IFN-γ and improve the cellular immune response to PRRSV. GP5aa96-104,N-1aa106-114and N-2aa49-57can significant restrain the secretion of IL-10,suggest us that GP5aa96-104, N-1aa106-114and N-2aa49-57would weaken thereplication of PRRSV and enhance the immune response.N-1aa106-114peptidepossibly promotes the secretion of IFN-γ at the28d of PRRSV vaccination andadvance the immunity.