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In this study, 108 P. multocida isolates recovered from various host animals such as cattle, buffalo, swine, poultry (chicken, duck, and emu) and rabbits were screened for carriage of 8 virulence associated genes. The results revealed some unique information on the prevalence of virulence associated genes among Indian isolates. With the exception of toxA gene, all other virulence associated genes were found to be regularly distributed among host species. Association study between capsule type and virulence genes suggested that pfhA, nanB, and nanH genes were regularly distributed among all serotypes with the exception of CapD, whereas toxA gene was found to be positively associated with CapD and CapA. The frequency of hgbA and nanH genes among swine isolates of Indian origin was found to be less in comparison to its equivalents around the globe. Interestingly, very high prevalence of tbpA gene was observed among poultry, swine, and rabbit isolates. Likewise, very high prevalence of pfhA gene (95.3%) was observed among Indian isolates, irrespective of host species origin.

Identification of outer membrane proteins (OMPs) is important to understand the bacteria structure and function, host-pathogen interaction, development of novel vaccine candidates, and diagnostic antigens. But till now the key antigens of P. multocida B:2 isolate causing haemorrhagic septicaemia (HS) in animals are not clearly defined. In this study, P52 strain of P. multocida serotype B:2 was grown in vitro under iron-rich and iron-limited condition. The OMPs were extracted by sarkosyl method followed by SDS-PAGE and the proteins were identified by MALDI-TOF/MS analysis. In total, 22 proteins were identified, of which 7 were observed exclusively under iron-limited condition. Most of the high molecular weight proteins (TbpA, HgbA, HgbB, HasR, IroA, and HemR) identified in this study were involved in iron acquisition. Some hypothetical proteins (HP-KCU-10206, HP and AAUPMB 08244, HP AAUPMB 21592, HP AAUPMB 19766, AAUPMB 11295) were observed for the first time in this study which could be unique to serotype B:2. Further functional in vivo study of the proteins identified are required to explore the utility of these proteins in developing diagnostics and vaccine against HS.

Aim: The present study was undertaken to clone, sequence and analyze the hsf, an outer membrane protein gene of Pasteurella multocida serotype B:2 Materials and Methods: hsf gene was amplified from genomic DNA of P. multocida. Polymerase chain reaction (PCR) product was cloned in pET-32a vector and was characterized. hsf gene was sequenced, analyzed and phylogenetic tree was constructed taking sequences of other strains.Results: Amplicon size was found to be 785 bp. Recombinant got characterized through colony PCR and restriction enzyme analysis.Conclusion: hsf gene of P. multocida serotype B is similar to serotype A, but different from serotype D. Further work is needed to evaluate role of Hsf protein in protection studies and to study the antigenic properties of this recombinant protein as a candidate for vaccine.

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