绿藻气球菌(A.viridans)是一种重要的机会性人畜共患病原体,对畜牧业构成潜在威胁,比如奶牛乳腺炎,由于多重耐药菌株的广泛发展。噬菌体溶素已成为有希望的替代抗生素治疗策略。然而,没有报道溶素治疗A.viridans感染。在这项研究中,揭示了第一个A.viridans噬菌体溶素AVPL的关键活性域和关键活性位点。AVPL由N-末端N-乙酰胞壁酰-L-丙氨酸酰胺酶催化结构域和包含两个保守LysM的C-末端结合结构域组成。H40、N44、E52、W68、H147、T157、F60、F64、I77、N92、Q97、H159、V160、D161和S42被鉴定为维持催化结构域活性的关键位点。LysM基序在将AVPL与细菌细胞壁肽聚糖结合中起关键作用。AVPL在4-45°C的温度范围和4-10的pH范围内保持稳定的活性,其活性与金属离子的存在无关。体外,AVPL的杀菌效果在牛奶样品中显示出有效的杀菌活性,用2µg/mL的AVPL在1小时内将A.viridans减少约2Log10。此外,单剂量(25µg)的溶素AVPL显着降低小鼠乳腺中的细菌负荷(约2Log10),改善乳腺炎病理学,并降低炎性细胞因子(TNF-α,IL-1β,和IL-6)在乳腺组织中。总的来说,这项工作提供了一种新的替代治疗药物,用于治疗由耐多药A.viridans引起的乳腺炎。
目标:A.viridans是一种已知引起各种疾病的人畜共患病原体,包括奶牛的乳腺炎。近年来,该病原体的抗生素耐药菌株或多重耐药菌株有所增加。噬菌体溶素是治疗由多重耐药菌株引起的感染的有效方法。这项研究揭示了第一个被命名为AVPL的A.viridans噬菌体溶素的生物学特性和关键活性位点。AVPL能有效杀灭巴氏杀菌全脂乳中的耐多药绿脓杆菌。重要的是,25μgAVPL显著减轻了由A.viridans诱导的小鼠乳腺炎的症状。总的来说,我们的结果证明了溶素AVPL作为抗微生物剂用于治疗由A.viridans引起的乳腺炎的潜力。
Aerococcus viridans (A. viridans) is an important opportunistic zoonotic pathogen that poses a potential threat to the animal husbandry industry, such as cow mastitis, due to the widespread development of multidrug-resistant strains. Phage lysins have emerged as a promising alternative antibiotic treatment strategy. However, no lysins have been reported to treat A. viridans infections. In this study, the critical active domain and key active sites of the first A. viridans phage lysin AVPL were revealed. AVPL consists of an N-terminal N-acetylmuramoyl-L-alanine amidase catalytic domain and a C-terminal binding domain comprising two conserved LysM. H40, N44, E52, W68, H147, T157, F60, F64, I77, N92, Q97, H159, V160, D161, and S42 were identified as key sites for maintaining the activity of the catalytic domain. The LysM motif plays a crucial role in binding AVPL to bacterial cell wall peptidoglycan. AVPL maintains stable activity in the temperature range of 4-45°C and pH range of 4-10, and its activity is independent of the presence of metal ions. In vitro, the bactericidal effect of AVPL showed efficient bactericidal activity in milk samples, with 2 µg/mL of AVPL reducing A. viridans by approximately 2 Log10 in 1 h. Furthermore, a single dose (25 µg) of lysin AVPL significantly reduces bacterial load (approximately 2 Log10) in the mammary gland of mice, improves mastitis pathology, and reduces the concentration of inflammatory cytokines (TNF-α, IL-1β, and IL-6) in mammary tissue. Overall, this work provides a novel alternative therapeutic drug for mastitis induced by multidrug-resistant A. viridans.
OBJECTIVE: A. viridans is a zoonotic pathogen known to cause various diseases, including mastitis in dairy cows. In recent years, there has been an increase in antibiotic-resistant or multidrug-resistant strains of this pathogen. Phage lysins are an effective approach to treating infections caused by multidrug-resistant strains. This study revealed the biological properties and key active sites of the first A. viridans phage lysin named AVPL. AVPL can effectively kill multidrug-resistant A. viridans in pasteurized whole milk. Importantly, 25 μg AVPL significantly alleviates the symptoms of mouse mastitis induced by A. viridans. Overall, our results demonstrate the potential of lysin AVPL as an antimicrobial agent for the treatment of mastitis caused by A. viridans.