Researchers at United Biomedical Inc. and universitycollaborators have taken the region in the AIDS virus thatprompts the best immune response and created an eightfoldmolecular version of it, with this "octameric" molecule givingpromising results in animal studies of its vaccine potential.

Reporting Friday in Science, the researchers took a peptidecore bearing eight reactive sites, and joined each core to eightidentical peptide molecules, each comprising the V3 region ofthe virus' gp120 coat protein.

The V3 region, or principle neutralizing determinant of the HIVenvelope protein, is a target for the immune system's attackon the virus. The V3 loop of the virus remains relativelyconstant among HIV strains and is also the region crucial inseveral infective actions of the virus, such as its geneticreplication and its fusing together of T cells.

To enhance the immune potential of the V3 peptide, theresearchers attempted to increase its rate of presentation tothe immune system by the octamer strategy.

Together with scientists at the University of California, SanDiego, and researchers at Rockefeller University, scientists atUnited Biomedical of Lake Success, N.Y., showed that theoctameric V3 molecule raised antibody levels to levels 30 to50 times higher than those raised by a vaccine made with asingle V3 molecule.

Although the antibodies to the octamer took longer to developthan with the monomer, by week 37 after immunization, theoctamer had elicited higher levels, which remained sustainedwith booster shots, for three and a half years.

The octameric vaccine made with the V3 loop of the HIV strainIIIB, displayed "significant cross-neutralization" to other HIVstrains, RFII and MN, the researchers wrote.

A sixfold version of the vaccine is also displaying promisingactivity, and the researchers are extending their studies,which in the present report were conducted with guinea pigs,to non-human primates. Strains of virus isolated directly fromhumans, as opposed to the laboratory-grown strains reportedon here, will also be tested.

-- Roberta Friedman, Ph.D. Special to BioWorld

(c) 1997 American Health Consultants. All rights reserved.