AUTHOR=Li Donghai , Huo Caiyun , Li Guiping , Zhu Menghan , Xu Fuzhou , Qiao Jian , Sun Huiling 

TITLE=The absence of luxS reduces the invasion of Avibacterium paragallinarum but is not essential for virulence

JOURNAL=Frontiers in Veterinary Science

VOLUME=11

YEAR=2024

URL=https://www.frontiersin.org/journals/veterinary-science/articles/10.3389/fvets.2024.1427966

DOI=10.3389/fvets.2024.1427966

ISSN=2297-1769

ABSTRACT=<p>The contagious respiratory pathogen, <italic>Avibacterium paragallinarum</italic>, contributes to infectious coryza in poultry. However, commercial vaccines have not shown perfect protection against infectious coryza. To search for an alternative approach, this research aimed to investigate whether the quorum-sensing system of pathogens plays a crucial role in their survival and pathogenicity. The LuxS/AI-2 quorum-sensing system in many Gram-negative and Gram-positive bacteria senses environmental changes to regulate physiological traits and virulent properties, and the role of the <italic>luxS</italic> gene in <italic>Av. paragallinarum</italic> remains unclear. To investigate the effect of the <italic>luxS</italic> gene in the quorum-sensing system of <italic>Av. paragallinarum</italic>, we constructed a <italic>luxS</italic> mutant. Bioluminescence analysis indicated that the <italic>luxS</italic> gene plays a vital role in the LuxS/AI-2 quorum-sensing system. The analysis of the LuxS/AI-2 system-related genes showed the level of <italic>pfs</italic> mRNA to be significantly increased in the mutant strain; however, <italic>lsrR</italic>, <italic>lsrK</italic>, and <italic>lsrB</italic> mRNA levels were not significantly different compared with the wild type. The ability of the <italic>luxS</italic> mutant strain to invade HD11 and DF-1 cells was significantly decreased compared with the wild-type strain. In addition, all chickens challenged with various doses of the <italic>luxS</italic> mutant strain developed infections and symptoms, and those challenged with the lowest dose exhibited only minor differences compared to chickens challenged with the wild-type strain. Thus, the deletion of the <italic>luxS</italic> gene reduces the invasion, but the <italic>luxS</italic> gene does not play an essential role in the pathogenesis of <italic>A. paragallinarum</italic>.</p>