HIV adapts to 'escape' immune response

Posted By News On February 27, 2009 - 6:50pm

BIRMINGHAM, Ala. – The human immunodeficiency virus (HIV) adapts so well to the body's defense system that any successful AIDS vaccine must keep pace with the ever-changing immunological profile of the virus, according to researchers at the University of Alabama at Birmingham (UAB) and the University of Oxford in England.

A new study better describes HIV's ability to adapt by spelling out at least 14 different "escape mutations" that help keep the virus alive after it interacts genetically with immunity molecules that normally attack HIV.

The researchers analyzed genetic data from more than 2,800 HIV-infected patients on five continents. The findings are published online in the journal Nature.

"Key genetic regions of HIV introduced into individuals of different ancestry in different places have been evolving to a greater or lesser degree according to inherited factors controlling immune response," said Richard Kaslow, M.D., a professor in the UAB School of Public Health and a co-author of the study. "If HIV adapts differently in genetically distinct hosts, the challenge ahead in vaccine design is formidable," he said.

The researchers looked at different DNA variations of HIV in conjunction with different forms of human leukocyte antigen (HLA), a group of molecules that orchestrate immune response. Normally HLA molecules present fragments of HIV proteins on the surface of infected cells to the immune system, acting as a signal for HIV destruction.

The Nature study shows just how efficiently the virus evolves escape mutations that help infected cells avoid destruction, Kaslow said. HLA genes themselves vary considerably across populations, most likely due to many biological and environmental factors that researchers are just beginning to understand.

The future of vaccine exploration will need to address the escape mutation capacity and identify new drug targets that work against an ever-changing HIV immunology landscape, said Philip Goulder, M.D., a professor of immunology at the University of Oxford and the study's senior author.

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