Genomic relatedness among Actinobacillus pleuropneumoniae field strains ofserotypes 1 and 5 isolated from healthy and diseased pigs

Forty-four Actinobacillus pleuropneumoniae isolates recovered from both hea lthy and diseased pigs were characterized by random amplified polymorphic D NA analysis (RAPD), pulsed field gel electrophoresis (PFGE) and apr toxin g ene typing. Nine RAPD types and 14 PFGE patterns were identified. No common RAPD or PFGE patterns were found between strains of serotype I and those o f serotype 5, The RAPD analysis indicated that the 15 serotype 1 strains is olated from diseased pigs were assigned to 4 RAPD types, with 66% of strain s characterized by the same RAPD type. By contrast, the 5 strains of seroty pe 1 isolated from healthy carriers were dispersed in 4 RAPD types. These d ata suggest that the diversity of strains isolated from healthy pigs could be higher than that of strains recovered from diseased pigs, In addition, a ll serotype 5 strains exhibited a unique RAPD type. Unlike RAPD, PFGE analy sis allowed discrimination among isolates of serotype 1 and among those of serotype 5, All but 3 isolates showed the same apr genotype as their respec tive serotype reference strain. These data indicate that RAPD analysis is a valuable rapid tool for routine subtyping of strains of serotype I. For st rains of serotype 5, a combination of several typing methods, such as PFGE and apr gene typing, is needed to provide vide useful information on the mo lecular epidemiology of swine pleuropneumonia molecular epidemiology of swi ne pleuropneumonia.