Prevalence of different OmpH-types among Pasteurella multocida isolated from lungs of calves with respiratory problems

The objective of this study was a comparative analysis of the ompH gene sequences from 83 isolates and four Russian reference strains of P. multocida to assign them to the allelic variants of the gene (OmpH-types). In addition, the above P. multocida strains have been characterized on the basis of capsular serotypes and virulence-associated genes. The isolates were classified into the OmpH -types based on allele specific PCR and gene fragment sequencing. The isolates of capsular serotype A have been subdivided into 6 OmpH -types, of which the most common types identified were A1 and A2. All capsular serotype D isolates belong to the same OmpH-type (D1). On 16 of a total of 23 farms all isolates belong to only one OmpH-type, on 4 farms - to 2, and on 3 farms - to three OmpH-types. The tbpA and pfhA genes were found more often in the isolates of capsular group А as compared to capsular group D (p ≤ 0.05). OmpH-types of serogroup А differ significantly (p ≤ 0.05) among themselves by the prevalence of the pfhA and hgbB genes.