HIV Uses Unique Strategy To Evade Attack by Antibodies, Study Says; Research Could Help Lead to Vaccine

HIV uses "different strategies" to evade attack by immune system antibodies, according to a study published in the March 20 issue of the journal Nature, Reuters reports (Reuters, 3/19). Howard Hughes Medical Institute researcher George Shaw and a team of colleagues from the University of Alabama-Birmingham found that HIV continually alters the arrangement of large sugar molecules studded across its gp120/41 protein coat, or outer envelope, effectively blocking the docking stations for attacking antibodies. Shaw called the changing protein coat a "glycan shield" and said that the team was "surprised at the rapidity and extent to which the replicating virus population in infected patients escaped antibody recognition." Antibodies also change structure to adapt to the altered virus structure but have difficulty keeping up with the speed of the virus changes. Shaw said that despite HIV's "resourcefulness," there is "hope" that the new research could help lead to the development of a vaccine to protect HIV-negative individuals from infection (HHMI release, 3/19). The research "allows us to better understand how HIV-1 is able to avoid immune elimination," Shaw said, adding, "On a practical level it provides a tool to assess the activity of candidate vaccines" (Reuters, 3/19). Shaw said that the glycan shield is one of "several" mechanisms that HIV uses to escape attacking antibodies. "The trick will be to understand these mechanisms more fully and to find the Achilles' heel. We are not there yet," he added (HHMI release, 3/19).