"Complete HIV eradication is not required. The immune system can control HIV." This bold statement comes from American Bruce Walker who says this is the most important lesson from his research on anti-HIV immunity. But to achieve this, one exacting condition must be met, Walker said: "Acute HIV infection should be treated immediately, pre-seroconversion, with potent antiviral therapy."

Current emphasis on viral eradication stems from the predominance of virologists in HIV research, Walker said. "We need to bridge the gap between immunologists and virologists," he added.

Walker's analysis of the immune system of the "Berlin patient," an HIV-positive man who has undetectable plasma virus 18 months after stopping therapy, supports his conclusion. This patient has the kind of immunity that Walker thinks is necessary to keep HIV in check. His evidence suggests that such immunity might be attainable in all HIV-infected persons.

Previously Walker reported that long-term nonprogressors (LTNP) have CD4 cells called cytotoxic lymphocytes (CTLs) specifically directed against HIV antigens. Generation of CTLs also correlates with control of viremia early after infection. Yesterday he reported that HIV suppression depends on virus-specific CD4 T-helper cells, which are essential to generate HIV-specific CTLs. In a cohort of LTNP followed by researcher Susan Buchbinder who have remained asymptomatic for up to 19 years, the level of specific T-helper cells correlates inversely with viremia.

Treatment of HIV: The task is to protect activated T-helper cells during acute infection.

But, Walker noted, "Activated T-helper cells are precisely the targets for HIV." The task is to protect them during acute infection. Walker proved this is possible in twelve persons identified with acute infection and treated with HAART prior to seroconversion. Viral RNA became undetectable in all. By two to three months, HIV-specific T-helper cells appeared; by six months, this response became "quite strong" in several individuals. As predicted, virus-specific CTLs also arose. "Every infected patient has the ability to generate HIV-specific T-helper cells," Walker concluded. "We can predictably preserve this response by treating early during infection."

Can therapy be discontinued in persons with undetectable virus and a strong CTL response? "I'm in no way advocating that people treated early stop therapy," Walker stressed. "But we could do a controlled trial."

this story can also be found in The Bridge, the onsite print newspaper

back