What is the most commonly performed confirmatory method for HIV infection?

The Western blot is considered the most commonly performed confirmatory method for HIV infection due to its specificity and reliability. Following initial screening tests, such as enzyme immunoassay (EIA) or rapid antibody tests, which may yield false positives, the Western blot serves as a more definitive test. This method utilizes electrophoresis to separate proteins from the HIV virus and then applies a secondary antibody to detect the specific proteins associated with HIV.

Western blot's confirmation process involves identifying patterns of HIV-specific antibodies, effectively distinguishing between true HIV infections and cross-reactivity that may occur with other infections. Its ability to confirm the presence of various HIV proteins makes it a trusted method in clinical settings.

Other methods, like Polymerase Chain Reaction (PCR), while useful in diagnosing HIV, especially in acute infections or for monitoring viral load, are not routinely used for confirmatory testing. PCR detects the viral RNA rather than the antibodies raised against the virus. Enzyme immunoassays can serve as initial screenings but lack the confirmatory characteristics of the Western blot. Rapid antibody tests offer the advantage of quick results but are primarily used for screening rather than confirmation of an active infection. Thus, the Western blot remains the gold standard in confirming HIV infection.