This paper describes the use of two antigens in ELISAs for the diagnosis of A. pleuropneumoniae (serotypes 3, 5 and 7) infections in Brazil. One antigen comprised the aqueous fraction obtained by phenol extraction from bacterial cultures (FAF) and the other was composed of long lipopolysaccharide chains (LPS-CL). Mono and polyvalent ELISA systems were standardized with the prevalent serotypes. Discriminating equations were developed with the ELISA’s results obtained with two sets of serum samples. One set of sera had been collected from piglets free from A. pleuropneumoniae infections (known negative sera) and the other set collected from inoculated piglets after seroconversion (known positive sera). The results were compared using the generalized distance of Mahalanobis, the coefficient of determination, the F test, the global coefficient, the sensitivity, and the specificity. The results obtained with the FAF antigen were superior regarding all the evaluated parameters. However, the FAF-ELISA resulted in unexpected positive reactions with serum samples collected from animals that had been inoculated with heterologous serotypes (2 and 9). The sensitivity and the specificity of both tests ranged from 91.5 to 95.7, indicating that these two antigens are appropriate for use in A. pleuropneumoniae screening tests, as they can detect serotypes 3, 4, 5, 6, 7 and 8.
Swine; Actinobacillus pleuropneumoniae; pleuropneumonia; ELISA
