Newly Identified CCR5 Variants May Confer HIV Protection In Asians

BANGKOK (Reuters Health) - New variants of the HIV CCR5 receptor gene have been identified that appear to influence susceptibility and rate of progression in Vietnamese and Cambodian populations, researchers reported here at the XV International AIDS Conference.

Dr. Corrine Capoulade-Metay of INSERM-U543, Paris, working with colleagues at the Pasteur Institute in Ho Chi Minh City and Phnom Penh, identified five new CCR5 variants, two of which appear to result in significant modifications of receptor and coreceptor functions that influence HIV-1 transmission.

Some individuals do not become infected with HIV-1, even after many exposures to the virus, the investigators note. One CCR5 receptor gene variant, specifically, homozygosity for a 32-base pair deletion, has been shown to confer resistance to infection. But while frequent in Caucasian populations, this variant is "extremely rare" in Asian populations.

To see if there were a protective CCR5 variant present in Asian populations, Dr. Capoulade-Metay's group evaluated HIV-infected injection drug users, HIV-negative but exposed injection drug users, and healthy controls in Vietnam. In Cambodia, they examined HIV-infected subjects, their HIV-negative partners, and healthy controls.

After performing DNA sequencing studies, the researchers identified a total of five variants that exhibited low frequencies. These comprised G106R, C269F, S185R, I254T and R223Q in the Vietnamese. G106R and R223Q variants were also seen in the Cambodians.

Two of the mutations -- G106R and C296F -- exhibited "significant modification of HIV receptor and coreceptor properties," Dr. Capoulade-Metay reported. Specifically, the heterozygous forms of these two mutations were associated with a lower infectivity compared with wild type.

Based on these observations, she postulates that the presence of "these two variants could modify HIV infectivity in Asian populations."

MeSH Headings: Congresses : Health Care Economics and Organizations : Immunologic and Biological Factors : Immunologic Factors : Membrane Proteins : Organizations : Receptors, Cell Surface : Receptors, Immunologic : Receptors, Virus : Receptors, HIV : Receptors, Cytokine : Receptors, Chemokine : Receptors, CCR5 : Chemical Actions and Uses : Chemical Actions : Chemicals and Drugs : Health Care

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