Originally Posted by bh_boyy2
Oh God! That's a lot of wrong information about HIV tests in this topic.
I'll try to help a little:
The tests that search for the presence of antibodies (ELISA and Western Blot) are older than the PCR based techniques, but are still the most used to confirm or rule out the presence of an infection. The Viral Load test is RT-PCR procedure, in which you have a Reverse Transcription of the HIV RNA followed by a PCR amplification of the cDNA. It is not used to confirm or rule out an infection, since it has a detection threshold of a few thousand viral copies (it is a semi-quantitative method). The gold standard for HIV detection is what can be called a qualitative PCR. In this method the DNA of lymphocytes is extracted and tested for the presence of the integrated HIV provirus (the provirus of a retrovirus virus is its "DNA form", after the reverse transcription and integration steps). This test is used only in cases where both ELISA and Western Blot tests are repeatedly negative but the patient has nonetheless convincing clinical signs of AIDS.
And by the way, when one gets a positive HIV result, it is a composite of at least two tests (usually an ELISA and a Western Blot. The former is very sensitive and the latter has a high specificity).