Sudheesh Ponnerassery S, Crane Samuel, Cain Kenneth D, Strom Mark S
Northwest Fisheries Science Center, NOAA Fisheries Service, 2725 Montlake Boulevard East, Seattle, Washington 98112, USA.
Dis Aquat Organ. 2007 Dec 13;78(2):115-27. doi: 10.3354/dao01859.
Renibacterium salmoninarum, the causative agent of bacterial kidney disease in salmonid fishes, is a Gram-positive diplococcobacillus belonging to the family Micrococcaceae. Analysis of the genome sequence of the bacterium demonstrated the presence of a sortase homolog (srtD), a gene specifying an enzyme found in Gram-positive bacteria and required for covalent anchoring of cell surface proteins. Interference of sortase activity is being examined as a target for therapeutic prevention of infection by several pathogenic Gram-positive bacterial species. In silico analysis identified 8 open reading frames containing sortase recognition motifs, suggesting these proteins are translocated to the bacterial cell wall. The sortase and potential sortase substrate genes are transcribed in R. salmoninarum, suggesting they encode functional proteins. Treatment of R. salmoninarum with phenyl vinyl sulfone (PVS) significantly reduced bacterial adherence to Chinook salmon fibronectin. In addition, the ability of the PVS-treated bacteria to adhere to Chinook salmon embryo cells (CHSE-214) in vitro was dramatically reduced compared to that of untreated bacteria. More importantly, PVS-treated bacteria were unable to invade and replicate within CHSE-214 cells (demonstrated by an intracellular growth assay and by light microscopy). When treated with PVS, R. salmoninarum was not cytopathic to CHSE-214 cells, whereas untreated bacteria produced cytopathology within a few days. These findings clearly show that PVS, a small molecule drug and a known sortase inhibitor, can interfere with the ability of R. salmoninarum to adhere and colonize fish cells, with a corresponding decrease in virulence.
鲑肾杆菌是鲑科鱼类细菌性肾病的病原体，是一种属于微球菌科的革兰氏阳性双球菌杆菌。对该细菌的基因组序列分析表明存在分选酶同源物（srtD），该基因编码革兰氏阳性细菌中发现的一种酶，是细胞表面蛋白共价锚定所必需的。分选酶活性的干扰正作为几种致病性革兰氏阳性细菌感染的治疗性预防靶点进行研究。计算机分析鉴定出8个含有分选酶识别基序的开放阅读框，表明这些蛋白质被转运到细菌细胞壁。分选酶和潜在的分选酶底物基因在鲑肾杆菌中被转录，表明它们编码功能性蛋白质。用苯乙烯基砜（PVS）处理鲑肾杆菌可显著降低细菌对奇努克鲑鱼纤连蛋白的粘附。此外，与未处理的细菌相比，经PVS处理的细菌在体外粘附奇努克鲑鱼胚胎细胞（CHSE-214）的能力显著降低。更重要的是，经PVS处理的细菌无法在CHSE-214细胞内侵袭和复制（通过细胞内生长试验和光学显微镜证实）。用PVS处理时，鲑肾杆菌对CHSE-214细胞无细胞病变作用，而未处理的细菌在几天内产生细胞病变。这些发现清楚地表明，PVS作为一种小分子药物和已知的分选酶抑制剂，可以干扰鲑肾杆菌粘附和定殖于鱼类细胞的能力，相应地降低其毒力。
