HIV variant might help vaccine search

The quest for an AIDS vaccine has been hampered by the human immunodeficiency virus’ (HIV) ability to present a moving target, befuddling the immune system. Antibodies made against the proteins that envelope the virus lose their effect when the protein shell changes shape. To solve this puzzle, researchers hope to identify stable parts of the viral proteins, particularly those the virus needs to invade a cell and replicate. A vaccine that spawns antibodies against such a conserved piece of protein might stop the virus, scientists reason.

In the January PLoS Medicine, researchers describe an unusual HIV envelope protein, found in a Kenyan woman, that arose from a minor mutation in the genetic material encoding it. HIV with this variant protein shell “was unusually sensitive to every antibody we tested,” says Julie Overbough, a virologist at the Fred Hutchinson Cancer Research Center in Seattle.

Moreover, inserting a replica of this protein piece into HIV strains known to resist the effects of antibodies made those strains susceptible to the antibodies.

Several hurdles remain before the new finding might contribute to vaccine development, Overbough cautions. Scientists would need to devise a way to share this mutation among other HIV strains infecting a person and to create a vaccine that elicits antibodies against this protein piece. Even then, a successful vaccine might also need to generate antibodies against troublesome portions of the morphing viral proteins, she says.

But it’s encouraging that this mutation could be introduced across HIV strains, she says.