Abstract
Pasteurella multocida is a gram-negative bacterium that is the causative agent of a wide range of infectious diseases such as avian cholera, atrophic rhinitis and pasteurellosis in various animal species, including cattle, pigs and birds. One of the key factors of its virulence is a capsule consisting of hyaluronic acid, which helps the bacterium to avoid phagocytosis and the immune response of the host. In this work, a comprehensive analysis of the nucleotide and amino acid sequences of the hyaD gene encoding hyaluronate synthase (PmHAS) in P. multocida of the serogroup A strains was carried out. Special attention is paid to single-nucleotide substitutions, which, despite their presence, do not change the catalytic domains of the enzyme, which ensures its stable enzymatic activity. The conservatism of the key regions of the hyaD gene creates difficulties for accurate diagnosis of serogroup A using standard genotyping methods. Within the framework of the study, a strategy for the development of specific TaqMan probes for the detection of gray group A based on variable gene regions is proposed. These molecular tests can significantly improve diagnostic accuracy and facilitate timely monitoring of infections caused by Pasteurella multocida. The obtained data emphasize the importance of further studies of single-nucleotide substitutions and their effect on bacterial virulence.