Molecular Study of Virulence Factors of Pasteurella Multocida Isolates from Sheep in Iran

Pasteurella multocida is responsible for significant infections of a wide range of animal species and human. The organism causes a variety of diseases which include pneumonic pasteurellosis of ruminants, porcine progressive atrophic rhinitis (PAR) in pigs, fowl cholera and bovine haemorrhagic septicaemia (HS). The pathogenicity of P.multocida is associated with various virulence factors include outer membrane and porin proteins like ompH, adhesins (ptfA, fimA, hsf-1, pfhA, tadD) and dermonecrotoxin (toxA). The aim of this study was to identify the presence of these virulence genes among ovine P.multocida isolates. Thirty P.multocida isolates obtained from sheep pneumonia cases were identified by bacteriological and biochemical methods. All the isolates were confirmed as P. multocida by PM-PCR using species specific primers, KMT1. Molecular capsular typing (CAP-PCR) showed that all of the isolates belonged to type A. All of the isolates harboured FimA and OmpH genes. The majority (93.3%) of the isolates contained PtfA , Hsf-1 and (90%) for ToxA. The frequency of TadD and PfhA genes was the lowest (36.6%). Presence of virulence factors of P.multocida isolates showed genetically potential in pathogenesis of ovine pneumonia. Further studies for phenotypic determination of virulence factors with ethology of pneumonia are suggested. Overall, investigations of virulence factors help us to selection of suitable strain for an effective vaccine production.