Characterisation of the Putative Antigenic Genes of the Outer Membrane Proteins of Pasteurella multocida B:2 Strain PMTB2.1 through in silico Analysis

Abstract

Outer membrane proteins (OMPs), usually found in Gram-negative bacteria, have long been shown to elicit immune responses in infected hosts. This tendency of OMPs to generate immune reactions makes them ideal candidates for vaccine development against pathogenic bacteria. Pasteurella multocida is a Gram-negative pathogen responsible for the economically significant veterinary disease, hemorrhagic septicemia (HS). HS is an endemic and highly fatal disease affecting buffaloes and cattle. In Malaysia, outbreaks of this disease cost about half a million USD each year. Thus, despite current treatment and prevention measures, HS is a prevalent issue that needs to be overcome. Pasteurella multocida subsp. multocida PMTB2.1, a Malaysian strain of the pathogen, has recently had its entire genome sequenced after being isolated from HS outbreaks in the region. Antigenic OMPs from this strain have since been identified and published for further characterisation. LptD, Wza, and TbpA are integral membrane proteins, while Pal is a peripheral membrane protein that has not been characterised in-depth. This study, therefore, aims to analyse these OMPs through in silico methods. First, protein homology modelling was performed using SWISS-MODEL, whereafter, the structures generated were validated using the SWISS-MODEL structure assessment page, PROCHECK, ERRAT, and PROSA programs. The Pal, Wza, and TbpA structures were good models, while the LptD structure was found to be a near-good model based on the validation performed. Analyses using BCPREDS, NetMHCpan4.1, and NetBoLAIIpan1.0 revealed that these four OMPs could potentially elicit humoral and cellular immune responses.