HIV-2 Slower, Just as Deadly as HIV-1, New Study Finds

Joakim Esbjornsson, PhD

New research is calling into question the previously held perception that HIV-2 is more benign than its sister virus, HIV-1.

In a long-term study conducted by investigators from Sweden, Britain, and Guinea-Bissau, HIV-2 was found to be just as deadly as HIV-1, albeit moving at a slower pace. They argue physicians should consider turning to antiretroviral therapy (ART) sooner than they have typically done in the past.

First author Joakim Esbjornsson, PhD, head of the Systems Virology Group at Sweden’s Lund University, said HIV-2’s reputation is due in part to a lack of research. Specifically, scientists have had few data regarding the time between infection and AIDS progression in HIV-2, and regarding mortality rates among HIV-2 patients.

“Many physicians that meet HIV-2 infected patients feel uncertain about when antiretroviral treatment should be initiated,” he told MD Magazine®. “This is in contrast to HIV-1 infected patients, where antiretroviral treatment generally are offered immediately after diagnosis (in accordance with the current treatment guidelines).”

In order to better understand the implications of HIV-2 infection, scientists looked at 2 decades (1990 - 2009) of health data on police officers in Guinea-Bissau. Patients within that group who were diagnosed with HIV-1 and HIV-2 were followed for an additional 4 years.

Investigators calculated time estimates of transition to AIDS, as well as T cell dynamics, and mortality. Mortality rates were compared with nearly 3000 patients who were not infected with HIV in order to establish a control group.

Among the patients in the study, 408 had HIV-1 (either before or during the study), and 464 patients had HIV-2. Of those, a total of 225 patients became infected with HIV-1 during the study period, and 87 contracted HIV-2 during the study.

The data showed it more years for patients with HIV-2 to progress to AIDS (14.3 vs 6.2), and patients with HIV-2 survived for a median of 15.6 years, in contrast to 8.2 years for patients with HIV-1.

However, in the end, nearly half of the patients infected with HIV-2 during the study period (43%) went on to develop AIDS. That’s compared with 54% of patients who contracted HIV-1 during the study period. Among the same group, 46% of HIV-1 patients died while 30% of HIV-2 patients died.

Though HIV-2 seems to progress more slowly, Esbjornsson said the prognosis for patients infected with HIV-2 is similar to that of people infected with HIV-1.

“Our study is the first to present reliable estimates from HIV-2 infection to AIDS or HIV-related death, and our results show that the disease trajectory is almost identical to that seen in HIV-1 infection—just on a lower pace,” he explained. “We interpret this as that HIV-2 infection will lead to AIDS and HIV-related death without antiretroviral therapy in the vast majority of infected individuals, similar to what is seen in HIV-1 infection.”

He said the data makes a pressing case that physicians ought to consider starting ART immediately following HIV-2 diagnosis, in the same manner they do with HIV-1.

“Moreover, it also reiterates previous calls for the urgency of a randomized clinical trial of antiretroviral treatment in HIV-2 infection,” he added.

Esbjornsson said that part of that research should focus on determining which combinations of ART therapies would best in HIV-2, since it is already known that certain ARTs that work on HIV-1 are ineffective against HIV-2.

The study, “Long-term follow-up of HIV-2-related AIDS and mortality in Guinea-Bissau: a prospective open cohort study,” was published online in The Lancet HIV.