New Research From West Africa Claims HIV-2’s Virulence May Has Been Underestimated.

HIV-2 is less easy to transmit, and typically viral loads in blood are one or two orders of magnitude lower than with HIV-1, at about 2500 copies/ml. However, the virus integrates into host DNA in the same amount as with HIV-1.

HIV-2 epidemiology reflects its animal origin - sooty mangabey monkeys that are a West African species with most wide spreading in Cape Verde, Guinea-Bissau, Sierra Leone, Gambia and also in Ivory Coast, Senegal, Nigeria and Mali.

Because HIV-2 is less virulent than HIV-1 and therefore less frequently transmitted, it has tended to be out-competed by HIV-1. Surveillance of HIV in pregnant women in Guinea-Bissau has shown that while HIV-1 prevalence was practically zero till the beginning of the 1990s, it had risen to 6% by 2008. In contrast, HIV-2 prevalence was 8% among 1987 and 1992 but decreased to 1% by 1008.

Researchers from the University of Oxford suggested that although progression to AIDS and death in HIV-2 infection was slower than with HIV-1, it was the rule rather than the exception, the estimates of progression of HIV-2 to AIDS and death had been underestimated. In his study, Professor Joakim Esbjörnsson looked at progression to AIDS and death among the Guinea-Bissau police cohort. Initiated in 1990, this includes 4820 members with HIV-1 and HIV-2, all police officers, 13% of them women.

The report of the study presented at last month's Conference on Retroviruses and Opportunistic Infections (CROI 2017) indicates that HIV-2 was nearly 90% lethal within 25 years of infection. The researchers explain this by that after 20 years of the initiation of the cohort, while 90% of people with HIV-1 had progressed to AIDS, so had 70% of their counterparts with HIV-2, showing that previous studies had considerably underestimated the mortality and morbidity due to HIV-2.

The research team concluded that it's necessary to pay more attention to epidemiological studies of HIV-2 and consider these novel findings in planning future research projects.