Host proteins involved in HIV infection: new therapeutic targets.

Current treatment of HIV/AIDS consists of a combination of three to five agents targeting different viral proteins, i.e. the reverse transcriptase, protease, integrase and envelope, and aims to suppress viral replication below detectable levels. This "highly active antiretroviral therapy" (HAART) has brought an enormous benefit for life expectancy and quality in HIV-1-infected individuals, at least in industrialized countries. However, significant limitations with regard to efficiency, drug resistance, side effect and costs still exist. Recent data suggest that cellular factors also represent useful targets for therapy. Here, we summarize findings from several genome-wide screens that identified a large number of cellular factors exploited by HIV-1 at each step of its life cycle. Furthermore, we discuss the evidence that humans are equipped with powerful intrinsic defense mechanisms against retroviruses but that HIV-1 has evolved elaborate ways to counteract or evade them. Preventing the use of host cell proteins obligatory for viral replication or strengthening the cellular defense mechanisms may help to reduce viral replication to harmless levels. A better understanding of the host factors that promote or restrict HIV-1 replication may thus lead to the development of novel therapeutics against HIV/AIDS.