The Immune Response of Anti-idiotype Antibodies against Porcine Reproductive and Respiratory Syndrome Virus Infection

The SPF pigs were infected with porcine reproductive and respiratory syndrome virus(PRRSV) experimentally. The results indicated that there were not only antibodies(Ab1) to PRRSV, but also the anti-idiotype antibodies(Ab2) to the Ab1 in the serum samples collected from the pigs infected with PRRSV. According to the differences of proteins with different isoelectric point, various kinds of IgG in the serum samples were separated and purified by using isoelectrofocusing(IEF). Ten SPF pigs were immunized with purified Ab2 to anti-PRRSV-GP5 and anti-PRRSV-M respectively, and then they were infected with PRRSV through nasal cavity 7 days after immunization. The serum samples were collected from the pigs infected with PRRSV, and the strains of PRRSV in the serum samples were isolated by using MARC-145 cell or identified with competitive IFA. Five samples collected from pigs immunized with the Ab2 to anti-PRRSV-GP5 were positive from 3 to 7 days post infection; 3 samples were negative from 14 to 63 days post infection; 2 samples were positive from 14 to 35 days post infection and became negative between 42 and 56 days post infection, one of them became positive 63 days post infection. Five samples collected from pigs immunized with the Ab2 to anti-PRRSV-M were positive from 3 to 7 days post infection; 2 samples were negative from 14 to 63 days post infection; 3 samples were positive from 14 to 35 days post infection and became negative between 42 and 56 days post infection, one of them became positive 63 days post infection. The results suggested that the immune response against PRRSV of Ab2 to anti-PRRSV-GP5 and anti-PRRSV-M is obviously,and these Ab2 could be used as substitute antigens of PRRSV-GP5 and PRRSV-M to stimulate swine to produce neutralization antibody providing protection against infection of PRRSV.