HIV-1, the strain of virus most common in the United States, and HIV-2, most prevalent in Western Africa, respond differently to anti-HIV drugs, and therapy for patients infected with both strains should be carefully chosen, according to a report and case study in the July 15 edition of Clinical Infectious Diseases.
The case study focused on a woman from Guinea Bissau infected with both strains of the virus whose therapy was guided by her HIV-1 blood-based viral levels; her HIV-2 levels were ignored. Although her initial drug regimen controlled her virus, switching to a regimen containing Videx, Viread, and Sustiva led to drop in CD4 cells from above 500 to just 169 in less than a year. Subsequent changes in her regimen failed to boost CD4 levels. Genetic tests showed that her HIV-2 viral load had soared after starting the Videx-Viread-Sustiva regimen.
Noting that HIV-2 is naturally resistant to nonnucleoside analogs and responds poorly to certain other antiretrovirals, the researchers say treatment decisions for patients coinfected with HIV-1 and HIV-2 should take both strains into consideration. 'Drugs known to be active against HIV-2 should be given,' they urge, 'and periodic measurement of HIV-2 loads must be performed.'