来自杜克大学及Meharry口腔医学院（Meharry Medical College）的研究人员发现牙龈卟啉菌蛋白酶（Porphyromonas gingivalis gingipain）结合结构域能够阻止HIV-1病毒侵入。 这一研究成果公布在《抗菌剂与化学治疗》杂志(Antimicrob Agents Chemotherapy，AAC)杂志上。文章第一作者为谢华（Hua Xie）医生。
作者解释说：尽管已推荐几种内源性口腔组织作为比较罕见的艾滋病毒口腔传播途径的传播结构，然而人们对口腔内细菌和HIV病毒之间可能存在的相互作用还少有了解。
Hua Xie医生即其同事通过筛检口腔细菌及其产物，了解了它们阻止HIV-1病毒侵入的能力，据研究者的报告，在细菌测试中，只有牙龈卟啉菌表现出有效的抗融合能力以及在不存在细胞毒素的状态下抑制HIV-1病毒被膜介导的融合发生。随后的试验证实，粘合结构域HGP44（牙龈卟啉菌产生的精氨酸特异性半胱氨酸蛋白酶）是抑制HIV侵入的功能机构。
研究者重组HGP44蛋白酶在约2.5微克分子的50%有效浓度时能抑制HIV-1复制，然而重组HGP44比直接从牙龈卟啉菌中提取的有效性略低。“可能是由于重组蛋白和牙龈卟啉菌的天然蛋白之间的差异造成”研究者推测说。
“研究结果指出牙龈卟啉菌产生的HGP44蛋白酶能够结合HIV-1外膜蛋白gp120阻止HIV-1侵入”研究者推断“HGP44蛋白酶对糖蛋白gp120的特异性结合作用，至少部分上是蛋白酶阻止HIV侵入的机制，而侵入是HIV感染的第一步”。
英文原文：
Protein From Endogenous Oral Bacteria Prevents HIV Viral Entry
The binding domain from Porphyromonas gingivalis gingipain prevents cell entry by HIV-1, according to a report in the September issue of Antimicrobial Agents and Chemotherapy.
Although several endogenous oral components have been proposed as mechanisms for the relatively rare transmission of HIV by the oral route, the authors explain, little information is available on the possible interactions between HIV and bacteria in the oral cavity.
Dr. Hua Xie from Meharry Medical College School of Dentistry, Nashville, Tennessee and colleagues screened oral bacteria and their products for their ability to inhibit HIV-1 entry.
Among the bacteria tested, the authors report, only P. gingivalis showed potent antifusion activity, and the inhibition of HIV-1 envelope-mediated fusion occurred without cytotoxicity.
Subsequent experiments identified the adhesion domain of HGP44, an arginine-specific cysteine proteinase (gingipain) produced by P. gingivalis, as the component responsible for inhibiting HIV entry.
A recombinant HGP44 inhibited HIV-1 replication at a 50% effective concentration of approximately 2.5 micromolar, the researchers note, somewhat less potently than did P. gingivalis extracts.
"This might be due to differences between recombinant protein and the native protein in the bacterial extract," the investigators speculate.
"The results of this study indicated that HGP44 of P. gingivalis could bind to gp120 and inhibited HIV-1 entry," the authors conclude. "The specific binding of P. gingivalis HGP44 to gp120 glycoprotein of HIV appears to be, at least in part, the mechanism by which gingipains inhibit HIV entry, a first step of HIV infection."
