The Characteristics Of Porcine Reproductive And Respiratory Syndrome Immune Status And Gamma-IFN-producing Cells In Different Classical Swine Fever Immune Status

Porcine reproductive and respiratory syndrome (PRRS) is a highly contagiousdisease which is caused by porcine reproductive and respiratory syndrome virus(PRRSV), characterized by sow reproductive disorders and weaned piglets respiratorydiseases. PRRS was found in the United States in1980s for the first time. From then,it had emerged cross many majority countries and regions in European. For China it wasconfirmed in1990s. Because of the special etiology and immunologicalcharacteristics of PRRS, there was not one kind of PRRS vaccine till now, whichcould protect the immunity system effectively. PRRS was harmful for the pig industryin a long time, and caused huge economic loss. We noticed, in China, that PRRSVand CSFV had mixed and the mixture had the infectivity in most farms. Therefore, thecorrelation between CSFV and PRRSV immune played a crucial role in our study.And the research on promoting factor critical in the cellular immune process of PRRSwas also crucially important. Finally the theoretical basis to develop the new safe andeffective PRRS vaccine could be provided.We randomly selected12from30weaned piglets of PRRSV, PRV and PCV-2were showed antibody-negative as the object of study. We refer to the test results ofthe the CSFV blocking rate of maternal antibodies to divided into CSFVantibody-positive group (+) and CSFV antibody-negative group (-) at the12weanedpiglets10days old, then feeding them isolate within3m of the pens of PRRSVantibody-positive pigs. After collected blood samples at21days old, we detect thePRRSV antibody levels and use the ELISpot to monitor the IFN-γ secreting cells inperipheral blood and detect the dynamic changes of secreted IFN-γ after treated withPRRSV-specific peptide which carrying T cell epitopes. The results show that thehigh-CSFV antibody groups have a lower PRRSV infection rate than the low-CSFVantibody groups; the high-CSFV antibody groups display a higher number of IFN-γ secretingcells; the PBL of porcine affected by PRRSV infection in the low-CSFV antibody groups didnot respond to stimulus with PRRSV-specific peptides. We obtained the following conclusions that pigs can be protected from PRRSV which had good response to CSFVvaccine, and their cellular immunity is active, which suggest that there is relevance betweenimmune response mechanism of CSF and PRRS to some extent.Then, we studied to the changes of gamma-IFN-producing cells by pigsinoculated with attenuated PRRSV TJM-F92attenuated strain in different CSFimmune status. First, we randomly selected16from30weaned piglets of PRRSV,PRV and PCV-2were showed antibody-negative as the object of study. Andinoculated with live swine fever thermo-stable vaccine (rabbit origin) at28days old,then grouped according to the pig of CSFV antibody levels at14d after vaccinated. Andthen inoculated with highly pathogenic porcine reproductive and respiratory syndromelive viaccine (TJM-F92attenuated strain, containing106tissue culture infective dose50/mL). We analyzed the dynamic changes of gamma-IFN-producing cells in PBLwere using ELISpot in14d and28d after vaccinated TJM-F92attenuated strain, andthen stimulated PBL culture with PRRSV-specific T cell epitopes peptides. Theresults that the CSFV antibody-positive groups were immunized PRRSV TJM-F92attenuated strain the body produced PRRSV antibody levels are significantlyincreased, and the number of PRRSV-specific gamma-IFN-producing cells in PBL arealso significantly increased(P<0.05); the PRRSV antibody positive rate and PRRSVantibody levels at28d were significantly higher than which at14d. We obtained thefollowing conclusions that the good CSF immune status condition can improve thebody’s immune response with and enhance PRRS immunity. The test results at28dcan used to evaluate the immune response level after inoculation with PRRSVTJM-F92attenuated strain.In this study, we put forward that PRRS-specific cellular immune response canbe active in good CSF immune status condition, and the ability of pig against PRRSVinfection can be promoted, and the body produces specific immune response aftervaccinated with PRRSV TJM-F92attenuated strain can be improved. Furthermore,we could explain that the immune-suppression which had been infected by PRRSVwas improved markedly. It prompted us that the immune responses of PRRS vaccinescould be monitored by IFN-γ.