HIV Infection and AIDS

The screening (ELISA) and confirmation (Western blot) tests for HIV-1 and HIV-2 infections provide highly reliably laboratory diagnosis of this serious infection. Nucleic acid-based amplification tests are therefore not currently important to establish the diagnosis. The drug treatment of HIV-1 infection and AIDS has experienced remarkable progress during the last 10–15 years, in contrast with the frustrations encountered in HIV vaccine development. However, the virus still cannot be eradicated from the body and lifelong combination therapy using three different drugs is necessary to suppress disease progression. So far, 24 drugs, belonging to seven classes, have been approved for the treatment of HIV infection and inhibit defined molecular stages of the HIV life cycle, including the reverse transcriptase, the protease, the integrase and coreceptors (CCR5/ CXCR4). CD41 cell counts and HIV viral load in plasma must be determined prior to the start of and monitored during therapy. When therapy is effective, HIV RNA should disappear from the peripheral blood. The Roche AMPLICOR version 1.5 conventional PCR assay has been widely employed for monitoring, but the Cobas Ampliprep/Cobas TaqMan system for automated nucleic acid extraction and reverse realtime PCR detection of HIV is a newer alternative. If the HIV RNA viral load increases during therapy, it is a sign either that the patient does not take the medication properly or that resistant HIV strains have been selected. Drug resistance is associated with characteristic point mutations
for each drug. DNA sequencing combined with algorithmic analysis of databases can identify which point mutations are associated with what drug resistance and be helpful in the choice of a different combination of drugs that may continue to suppress the HIV infection.