[Laboratory diagnosis in HIV infection].

The laboratory diagnosis of an HIV infection is mainly based on the detection of antibodies. Many reliable tests are commercially available. Although they have excellent characteristics (sensitivity and specificity above 99%), their positive predictive value is low in populations with a very low prevalence of HIV infections. Therefore, reactive screening tests must be validated by a confirmatory test in order to reduce the probability of false positive results to an acceptably low level, i.e. below 1%. The detection of HIV by cell culture, antigen detection or genome detection is less standardized and, as a single test, less sensitive than the antibody tests. It is useful as an additional investigation in cases where the results of antibody tests are equivocal.