Special aspects of the treatment of HIV-2-infected patients.

HIV-2 is responsible for a limited epidemic in West Africa. Around 20% of all infected patients will progress to AIDS, and will need antiretroviral therapy. Unfortunately, antiretrovirals were developed to suppress HIV-1 replication; not all of them are active against HIV-2, e.g. all nonnucleoside reverse transcriptase inhibitors or fusion inhibitors. Moreover, only three protease inhibitors have the same activity in HIV-1 and HIV-2: lopinavir, saquinavir and darunavir. Even if all nucleoside and nucleotide reverse transcriptase inhibitors appear to be equally efficient against HIV-2, different resistance pathways and an increased facility of resistance selection make their use much more difficult than in HIV-1. Integrase inhibitors have a potent inhibitory effect on HIV-2 replication, but questions about the best timing for their use remain unanswered, as well as those regarding the use of entry inhibitors in this setting. The lack of reliable monitoring tools adds to the difficulty of treating HIV-2-infected patients, mostly because the viral load is not as useful as it is in HIV-1, and the incomplete knowledge about resistance pathways limits the clinical usefulness of resistance testing. With all these limitations, HIV-2 treatment remains a challenge. Further research is urgently needed, since antiretroviral therapy is now becoming available in countries where the HIV-2 prevalence is significant. The need for appropriate guidelines for HIV-2 treatment has become an emergency.