AIDS Virus Destroys Immune Cells Fast

Two U.S. studies of simian immunodeficiency virus-infected monkeys found that during acute infection SIV immediately wipes out more than half the CD4 T-cells that might have recognized and helped fight it. "The findings may require a rethink of strategies to design HIV drugs and vaccines," said Dr. Mario Roederer of the National Institute of Allergy and Infectious Diseases.

"Specifically, 30 percent to 60 percent of CD4 memory T-cells throughout the body are infected by SIV at the peak of infection, and most of these infected cells disappear within four days," Roederer and colleagues wrote. "Furthermore, our data demonstrate that the depletion of memory CD4 T-cells occurs to a similar extent in all tissues. As a consequence, over one-half of all memory CD4 T-cells in SIV-infected macaques are destroyed directly by viral infection during the acute phase -- an insult that certainly heralds subsequent immunodeficiency." Vaccines would have to stop this process.

Research by Dr. Ashley Haase, of the University of Minnesota Medical School, and colleagues found not only does SIV directly kill CD4 cells, the virus also causes them to commit cellular suicide.

The full studies by the Roederer and Haase teams, "Massive Infection and Loss of Memory CD+ T Cells in Multiple Tissues During Acute SIV Infection" and "Peak SIV Replication in Resting Memory CD4+ T Cells Depletes Gut Lamina Propria CD4+ T Cells" were published in Nature (2005;doi:10.1038/nature03501 and doi:10.1038/nature03513, respectively).

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