Blocking enzyme-linked immunosorbent assay for detection of antibodies against Actinobacillus pleuropneumoniae serotype 6 in pig serum

A blocking enzyme-linked immunosorbent assay (ELISA) detecting antibodies a gainst Actinobacillus pleuropneumoniae (Ap) serotype 6 was developed. The b locking ELISA was based on the inhibition of a polyclonal antibody raised a gainst Ap serotype 6. Purified lipopolysaccharide from Ap serotype 6 was us ed as antigen. The blocking ELISA was tested against sera from pigs experim entally infected with the 12 serotypes of Ap biotype 1. Cross-reaction with serotypes 3 and 8 but not with other serotypes was observed. The sensitivi ty and specificity of the test on a herd level were evaluated with sera fro m herds naturally infected with serotypes 2, 6, 8 or 12 and with sera from herds free of infection with any Ap serotype. The blocking ELISA showed a h igh herd sensitivity (1.00 (0.79-1.00)) and specificity (0.97 (0.93-0.99)). (C) 2001 Elsevier Science B.V. All rights reserved.