TOXIN TYPING OF ACTINOBACILLUS-PLEUROPNEU MONIAE BY PCR

For the determination of the apx toxin genes in Actinobacillus pleurop neumoniae strains, Eve PCR reactions were developed which allow the de tection of the activator and structural genes and the secretion genes of the toxins ApxI, ApxII and ApxIII. The oligonucleotide primers were chosen in order to amplify characteristic parts of the activator and structural genes apxICA, apxIICA and apxIIICA, and the secretion genes apxIBD and apxIIIBD. The annealing temperature, of all five reaction was identical in order to allow the five reactions in a single PCR run . The differences in length between the individual amplified gene frag ments allowed all product fragments to be separated in a single electr ophoresis. This way, a typical toxin gene pattern could be obtained wh ich is characteristic for the five toxin gene groups of A. pleuropneum oniae including serotypes 1, 5a, 5b, 9 and 11 (group 1), serotypes 2, 4, 6 and 8 (group 2), serotype 3 (group 3), serotypes 7 and 12 (group 4), and serotype 10 (group 5). The identification of the toxin genes, which,have significance in virulence, enhance and facilitate different iation of A. pleuropneumoniae and allow the detection of serotypes wit h an atypical toxin pattern.