Genetic diversity of the genes encoding the outer membrane lipoprotein (omlA) of Actinobacillus pleuropneumoniae.

An allelic variation of the genes encoding the protective outer membrane lipoprotein (omlA) in Actinobacillus pleuropneumoniae was investigated with polymerase chain reaction (PCR)-restriction fragment length polymorphisms. Primers for PCR were selected from a conserved sequence compared between the omlA genes of A. pleuropneumoniae serotypes 1 and 5a. A DNA fragment of 970 bp was amplified from the genomic DNA of all 12 serotypes of A. pleuropneumoniae. The amplified DNA sequence specifically hybridized under a low stringent condition to the cloned omlA gene of A. pleuropneumoniae. Digestion of the amplified DNA with the enzymes either HinfI or VspI yielded specific polymorphic patterns, allowing discrimination of all serotypes into five distinct groups.