Virulence gene profiling of porcine Pasteurella multocida isolates of Assam

Aim: The present study was conducted to detect and identify the virulence genes in Pasteurella multocida isolates of porcine origin from Assam. Materials and Methods: A total of 21 porcine P. multocida isolates were subjected to capsular typing and detection of virulence-associated genes (pfhA, thpA, hghB, toxA. oma87, ompII, and nanB) using various polymerise chain reaction (PCR) methods reported elsewhere. Further, pathogenicity of the porcine isolates of P multocida was studied in mice. For each strain of P multocida selected for pathogenicity trial, the group of mice was injected intraperitoneally (i/p) with (0.1 ml of the inoculum prepared from respective field isolates. containing 10 organisms per ml. Results: Capsular typing of the isolates by multiplex PCR showed two capsular types, type A (66.66%) and type D (33.33%). All the isolates were positive for outer membrane protein genes, oma87 and ompH genes. Iron acquisition genes, thpA and hghB, were detected in 14.28% and 19.04% of the isolates. The dermonecrotoxin encoding gene, toxA, was present in 23.80% of the isolates. Filamentous hemagglutinin encoding gene, pfhA, was detected in 28.57%. The virulence gene distribution pattern of the isolates indicates the important role of the genes in disease pathogenesis. Conclusion: From the present study, it can be concluded that toxA gene is an important marker gene for defining the pathogenic potential of P multocida strains in swine.