Which technique is used for the confirmation of infection with human immunodeficiency virus (HIV-1)?

The Western blot (immunoblot) assay is a key technique used for the confirmation of infection with human immunodeficiency virus (HIV-1) because it detects specific antibodies against HIV proteins in the patient's serum. While initial screening for HIV is often done using ELISA, which is highly sensitive, it can occasionally yield false positive results. Therefore, a more specific follow-up test is necessary to confirm the presence of the virus.

The Western blot assay does just that; it separates proteins based on molecular weight and then uses specific antibodies to detect those that are unique to HIV-1. This method is considered the gold standard for HIV confirmation because it provides not only confirmation of infection but also valuable information about the patient's immune response by determining which specific antibodies are present.

Other methods, such as Complement fixation and p24 antigen testing, are not standard for confirming an HIV infection. Complement fixation is not typically used for HIV detection, while p24 antigen testing is more useful in diagnosing acute HIV infection rather than confirming a chronic infection. Thus, the Western blot assay remains the definitive confirmatory test for HIV-1.