Application of an enzyme-linked immunosorbent assay to detect antibodies to Actinobacillus pleuropneumoniae serovars 1, 2 and 5 in the pig sera

An indirect and a sandwich enzyme-linked immunosorbent assay (ELISA), employing long-chain lipopolysaccharides (LC-LPS) and crude boiled extract as antigens respectively, were evaluated for the detection of antibodies against Actinobacillus pleuropneumoniae serovars 1, 2, 5, 9 and 11 in pig sera. By testing sera from pigs experimentally infected with the 10 recognized serovars, both assays were proven to have comparable sensitivity and specificity. With sera from pigs immunized with vaccines containing antigens of A. pleuropneumoniae serovars 1, 2 and 5, the assays were found to have a good correlation. The high diagnostic sensitivity and specificity of the indirect ELISA, along with its efficiency and ease of standardization-especially when using well-characterized antigens such as LC-LPS-may make it a valuable tool for field diagnostics.