Characterization of pseudorabies virus antibody responses in young swine after infection and vaccination by using an immunoglobulin M antibody capture enzyme-linked immunosorbent assay

An immunoglobulin M (IgM) antibody capture enzyme-linked immunosorbent assay (MACELISA) was developed for the detection of pseudorabies virus (PRV)-specific IgM antibody in swine sera because false-positive reactions frequently occurred when sera from older swine were tested with an indirect IgM enzyme-linked immunosorbent assay. Monoclonal mouse anti-swine IgM was used as the capturing antibody, and rabbit anti-PRV hyperimmune gamma globulin was used as the indicating antibody. Sera from non-PRV-infected, experimentally infected, vaccinated and challenged, passively immune and challenged, and naturally infected swine were evaluated. The PRV MACELISA had a specificity of 95% and was as sensitive and reproducible as previously reported in direct assays. An antibody response was still detectable with the MACELISA 21 days after inoculation. The PRV MACELISA did not detect a consistent antibody response in sera from swine vaccinated with either killed-PRV or modified live-virus vaccines but did detect an antibody response in sera from passively immune pigs after challenge with virulent PRV. These results indicated that the PRV MACELISA may be useful for the rapid serodiagnosis of recent PRV infection in swine.