Characterization of the pathogenicity and mechanisms underlying the pathogenesis of <i>Apibacter raozihei</i> , a potential bacterial pathogen

<i>Apibacter raozihei</i> is a Gram-negative bacterium isolated from the feces of bats, and there is a scarcity of information regarding its genomic and pathogenicity characteristics. This study systematically evaluated the pathogenic potential of <i>A</i>. <i>raozihei</i> by comparing the survival rates, bacterial loads in the peripheral blood and organs, histopathological lesions, and the production of proinflammatory cytokines in C57BL/6 mice infected with strains HY037 and HY041^T of <i>A</i>. <i>raozihei</i>. The findings revealed that mice infected with <i>A</i>. <i>raozihei</i> had low survival rates, with significant differences between the HY041^T and HY037 strains. The mice infected with HY041^T exhibited more severe pulmonary histopathological damage and higher levels of proinflammatory cytokines compared to those infected with HY037. These results demonstrated that <i>A</i>. <i>raozihei</i> is lethal in mice, causing significant pulmonary histopathological damage accompanied by the dysregulated secretion of proinflammatory cytokines in lung tissues and blood. The molecular mechanisms underlying their virulence were investigated through comparative analyses of the genomic and transcriptional profiles of HY041^T and HY037. The findings revealed that the genes encoding outer membrane protein A (OmpA), three peptidases, heat shock proteins, and proteins involved in lipopolysaccharide biosynthesis, and iron acquisition represent potential virulence factors of <i>A</i>. <i>raozihei</i>. In conclusion, this study established <i>A</i>. <i>raozihei</i> as a potential pathogen and identified significant differences in virulence across its strains, thereby enhancing our understanding of the pathogenesis of <i>A</i>. <i>raozihei</i>.