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October 11, 2006
Bacteria Protein Prevents HIV Entry (Reuters Health)
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."
