HIV: the virus and its two types

What it is

HIV is a retroviral infection, and the agent is an RNA virus. Two are named, HIV1 and HIV2. On the same page the complications named beside them are candidiasis, seen as oral thrush, and hairy leukoplakia. The two types are not only a naming; the testing algorithm separates them, in three steps. Step 1 is a fourth generation HIV test, which detects HIV sooner than the previously recommended antibody test by identifying the HIV viral protein, as much as 3-4 weeks sooner than the previous testing approach. Step 2 is an HIV-1/HIV-2 antibody differentiation immunoassay, which produces results sooner than the previously recommended Western blot and, unlike it, tells HIV-1 from HIV-2. Where step 2 is positive, the test results are interpreted as HIV-1 or HIV-2, and the diagnosis is HIV infection. Where step 2 is negative or indeterminate, step 3 is a nucleic acid test, which answers whether this is acute HIV-1 infection or a false positive from the fourth generation test: positive gives the diagnosis of acute HIV-1 infection, and negative marks the earlier result a false positive.