Monoclonal Anti-idiotipic Antibody Regulate PRRSV Immune Response

Porcine reproductive and respiratory syndrome (PRRS) is an acute infectious disease caused by Porcine reproductive and respiratory syndrome virus (PRRSV). PRRS mainly caused reproductive disorder, including of premature, abortion, fetal death, mummy and porcine respiratory syndrome at variety of ages and high mortality. The disease was first discovered in American in 1987 and then prevailed in many countries. In 1991, this disease was discovered in Taiwan. In 1996, Guo Baoqing first isolated a PRRSV strain from aborted fetuses and verified the evidence of PRRSV in our country. In 2006, there was a large outbreak in our South districts and this disease was diagnosed as highly pathogenic PRRS. The disease caused high morbidity and mortality and the clinical symptom became more complicated and the prevalence also was gradually expanded. At the present, PRRS has prevailed in the main worldwide pig-raising country and districts and caused pig-raising industry large economic losses. So it becomes one of the hot research areas.Our previous studies demonstrated that pigs infected with PRRSV produced auto-anti-idiotypic antibodies (auto-Ab2s) against idiotypic antibodies to M and GP5 protein, which may up- or down-regulate the immune responses against PRRSV infection. To explore the regulating effect of anti-idiotypic antibodies to PRRSV infection, we use the anti-idiotypic antibody specific to GP5 and its scFv to immunize mice and then challenge the mice with purified PRRSV, and at last we detect the antibody levels of the immunized mice by I-ELISA and the percentage of CD4+/CD8+ T cell in PBL by FCM, and do hemogram analysis. And because some reports indicate that different dosage of anti-idiotypic antibody have different regulating effect, we set three different dosage groups, with every group its own irrelevant control.After analysis of the statistics, we found that Mab2-5G2 and its scFv can enhance the immune response of PRRSV. It shows that they can increase the anti-GP5 antibody levels and the percentage of CD4+/CD8+ T cell in PBL, which may improve the mice immunity. In addition, we found that different dosage of immunogens have different effect, and only the mice immunized in the dosage of 0.025uM/mouse increase the percentage of CD4+/CD8+ T cell in PBL and the percentage of total lymphocyte in peripheral blood WBC, whereas the dosage of 0.025uM and 1.0uM/mouse immunogen can significantly reduce the percentage of CD4+/CD8+ T cell in PBL, which may weaken the mice immunity. In conclusion, our study demonstrates that the effect of anti-idiotypic antibody and its scFv can be influenced by different dosage, and this result pave the way for anti-idiotypic antibody and its scFv to be the immune regulator against PRRSV in pigs.