# Characterization of the pathogenicity and mechanisms underlying the pathogenesis of Apibacter raozihei, a potential bacterial pathogen

## TL;DR

This study shows that Apibacter raozihei is a harmful bacterium that can cause severe lung damage and inflammation in mice, with some strains being more dangerous than others.

## Contribution

The study identifies specific virulence factors and highlights strain-specific differences in pathogenicity of Apibacter raozihei.

## Key findings

- Mice infected with A. raozihei had low survival rates and severe lung damage.
- Strain HY041T caused more severe symptoms and higher cytokine levels than HY037.
- Genes like OmpA and those involved in iron acquisition are potential virulence factors.

## Abstract

Apibacter raozihei 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 A. raozihei 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 HY041T of A. raozihei. The findings revealed that mice infected with A. raozihei had low survival rates, with significant differences between the HY041T and HY037 strains. The mice infected with HY041T exhibited more severe pulmonary histopathological damage and higher levels of proinflammatory cytokines compared to those infected with HY037. These results demonstrated that A. raozihei 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 HY041T 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 A. raozihei. In conclusion, this study established A. raozihei as a potential pathogen and identified significant differences in virulence across its strains, thereby enhancing our understanding of the pathogenesis of A. raozihei.