Correlations between virulence gene profiles and other genetic factors of Pasteurella multocida strains isolated from...

Pasteurella multocida has a high genotypic variability, which allows it to cause a wide variety of diseases with huge economic losses worldwide. In this study, whole genome sequencing (WGS) of 66 P. multocida strains isolated from different host species was performed. By including an additional 23 strains selected from the NCBI database, genotypic characteristics of a total of 89 isolates were analysed. Sequence analysis revealed the strains' capsular serogroup, LPS genotype, multi-host (MH) and Rural Industries Research and Development Corporation (RIRDC) multilocus sequence typing (MLST). The most frequent serotype was A:L3, followed by F:3 and D:L6. The pattern of 10 virulence associated genes (fimA, hgbA, hgbB, hsf-1, hsf-2, nanH, pfhA, ptfA, tadD, tbpA) classified the strains into 10 new virulence gene profiles (VGPs), adding to the 13 VGPs described previously to provide a total of 23 VGPs. Some strains harboured multiple point mutations within tadD, that prevented primer binding during PCR, causing false negative results. New primers were designed to validate WGS findings and eliminate primer-binding mismatches, enhancing future diagnostic accuracy. A correlation was observed between the ompA gene sequences, MH and RIRDC STs of the strains and their VGP group. It was also observed that tbpA is only present in strains of ruminant origin, and further correlations were found between other genotypic characteristics of the strains and the occurrence of virulence genes.