Abstract:

Mycoplasma gallisepticum(MG) infection causes chronic respiratory disease (CRD) in chickens, adversely affecting feed conversion efficiency, egg production rate, hatchability, and chick activity, leading to significant economic losses in the global poultry industry. This study aims to analyze the genomic characteristics and biological features of the LC strain and explore the epidemiological patterns of MG in China. Pipped failure embryos were collected in hatchery for MG isolation. The isolate underwent whole-genome sequencing (WGS) and analysis of adhesion-related protein variations. Additionally, multilocus sequence typing (MLST) analysis was conducted to determine the prevalence of MG strains in China. Genomic analysis revealed a compact MG genome of 953.4 kb with a GC content of 31.5%. Annotation identified 721 coding regions with an encoding density of 89.3%, 33 tRNAs, and 2 CRISPR sequences. Functional enrichment in translation, metabolism, and signal transduction indicated efficient protein synthesis and environmental adaptability, with potential genes related to virulence regulation. Moreover, 11 amino acid mutations were identified in the adhesion-related proteins P1, P30, and hwm3. MLST analysis classified the isolate as ST-81, along with ST-78 and ST-36, which constitute the prevalent MG genotypes circulating in China. MG has become as a significant contaminant in hatcheries, along with their genetic diversity notably increasing control challenges. This study provides insights into the genomic and biological characteristics of the LC strain and elucidates the dominant MG sequence types in China, offering valuable scientific evidence for pathogen biology research and vaccine strain selection.

Key words: Mycoplasma gallisepticum, pipped failure embryo, genome, amino acid mutations, multilocus sequence typing (MLST)