Guo Mengjiao, Wang Haonan, Zhang Hao, Bo Zongyi, Zhang Chengcheng, Zhang Xiaorong, Wu Yantao
Jiangsu Co-Innovation Center for Prevention of Animal Infectious Diseases and Zoonoses, College of Veterinary Medicine, Yangzhou University, Yangzhou 225009, China.
Jiangsu Co-Innovation Center for Prevention of Animal Infectious Diseases and Zoonoses, College of Veterinary Medicine, Yangzhou University, Yangzhou 225009, China.
Vet Microbiol. 2025 Mar;302:110410. doi: 10.1016/j.vetmic.2025.110410. Epub 2025 Jan 26.
Infectious coryza (IC) is a respiratory disease in poultry caused by Avibacterium paragallinarum (Av. paragallinarum). The disease caused growth retardation in broilers and reduced egg production in laying hens, resulting in significant economic losses to the global chicken industry. The biofilm is an important virulence factor for many bacterial pathogens, yet there is a paucity of research on the biofilm of Av. paragallinarum. This study aimed to construct a random mutant library of Av. paragallinarum using the Tn5-Kan transposon to identify genes involved in biofilm formation. A total of approximately 3000 mutants were obtained, and 38 of them demonstrated a reduction in biofilm formation of 70-90 % by crystal violet staining. The transposon insertion sites were further determined by chromosome walking, and 17 functional genes related to biofilm formation were identified. According to the functional analysis of the mutated genes, 14 mutants with mutated genes associated with energy metabolism, cell membrane formation, gene transcription and translation, and material transmembrane transport were screened to further explore their biological characteristics and pathogenicity in vivo and in vitro. The results indicated that the growth performance, resistance to disinfectants, adhesion and invasion ability to DF-1 cells and pathogenicity of the 14 mutants were reduced. The 14 mutants displayed increased sensitivity to antibiotics but did not show significant changes in hemagglutination titer or antiserum bactericidal ability. It is noteworthy that the M-76 mutant exhibited a marked reduction in pathogenicity. Following challenge, the experimental chickens did not present any clinical symptoms or pathological changes for a period of seven days, and the respiratory tract bacterial shedding was also the lowest. This indicates that a deficiency in biofilm formation reduces the pathogenicity of Av. paragallinarum. This study will contribute to our understanding of the molecular mechanism of biofilm formation of Av. paragallinarum and further study the pathogenesis of Av. paragallinarum.
传染性鼻炎（IC）是由副鸡禽杆菌（Av. paragallinarum）引起的家禽呼吸道疾病。该病导致肉鸡生长发育迟缓，蛋鸡产蛋量下降，给全球养鸡业造成重大经济损失。生物膜是许多细菌病原体的重要毒力因子，但关于副鸡禽杆菌生物膜的研究较少。本研究旨在利用Tn5-Kan转座子构建副鸡禽杆菌随机突变体文库，以鉴定参与生物膜形成的基因。共获得约3000个突变体，其中38个通过结晶紫染色显示生物膜形成减少了70-90%。通过染色体步移进一步确定转座子插入位点，鉴定出17个与生物膜形成相关的功能基因。根据突变基因的功能分析，筛选出14个突变基因与能量代谢、细胞膜形成、基因转录和翻译以及物质跨膜运输相关的突变体，进一步探究其体内外生物学特性和致病性。结果表明，这14个突变体的生长性能、对消毒剂的抗性、对DF-1细胞的黏附与侵袭能力以及致病性均降低。这14个突变体对抗生素的敏感性增加，但血凝效价或抗血清杀菌能力未显示出显著变化。值得注意的是，M-76突变体的致病性显著降低。攻毒后，实验鸡在7天内未出现任何临床症状或病理变化，呼吸道细菌脱落也最低。这表明生物膜形成缺陷会降低副鸡禽杆菌的致病性。本研究将有助于我们了解副鸡禽杆菌生物膜形成的分子机制，并进一步研究副鸡禽杆菌的发病机制。
