By Liz Highleyman

HIV disease may be caused by either of 2 related viruses, HIV-1 or HIV-2. HIV-1 is responsible for most cases worldwide, while HIV-2 is found mostly in West African and among immigrants from that part of the continent. HIV-2 does not kill CD4 cells as aggressively as HIV-1, and the disease therefore progresses less rapidly. However, it can over time lead to AIDS.

As reported in the January 30, 2007 issue of AIDS, researchers compared the pattern of AIDS-defining events, CD4 cell counts at the time of AIDS diagnosis, survival from time of AIDS diagnosis, and CD4 counts near time of death among adult patients infected with HIV-1 or HIV-2 who attended Medical Research Council clinics in the Gambia. AIDS was diagnosed according to the expanded World Health Organization case definition for AIDS surveillance (1994).

Results

• 341 AIDS patients with HIV-1 and 87 with HIV-2 infection were enrolled.

• The most common AIDS-defining events in both groups were wasting syndrome and pulmonary tuberculosis.

• The median CD4 cell count at time of AIDS diagnosis was 109 cells/mm3 in patients with HIV-1 and 176 cells/mm3 in those with HIV-2 (P = 0.01)

• Median CD4 count remained significantly higher in HIV-2 patients after adjusting for age and sex (P = 0.03).

• The median time to death after AIDS diagnosis was 6.3 months in patients with HIV-1 and 12.6 months in those with HIV-2 (P = 0.03).

• In a multivariable analysis adjusting for age, sex, and CD4 cell count, the mortality rates of patients with HIV-1 and HIV-2 were similar (P = 0.25).

• The median CD4 cell count near the time of death was 62 cells/mm3 for patients with HIV-1 and 120 cells/mm3 for those with HIV-2 (P = 0.02).

Conclusion

"HIV-2 patients have a higher CD4 cell count at the time of AIDS, and a longer survival after AIDS," the investigators concluded. "The mortality after an AIDS diagnosis is more influenced by CD4 cell count than HIV type."

There has been much less research on treatment for HIV-2 compared with HIV-1. While approved non-nucleoside reverse transcriptase inhibitors (NNRTIs) do not work against HIV-2, some protease inhibitors appear to be effective.

02/06/07

Reference
E Martinez-Steele, A A Awasana, T Corrah, and others. Is HIV-2- induced AIDS different from HIV-1-associated AIDS? Data from a West African clinic. AIDS 21(3): 317-324. January 30, 2007.