Re: What is actually being tested when they test for viral load?

well, everyone seems to be debating other stuff, without specifically answering your question.
HIV viral load tests for the amount of HIV RNA (the virus’s genetic material – retroviruses are RNA viruses and don’t reverse transcribe to DNA until they are inside a host cell, when they are not detectable in blood tests) in a given unit of peripheral blood (usually number of copies per ml). There are several different technologies laboratories can use to quantify the amount of HIV:
reverse-transcriptase polymerase chain reaction (RT-PCR/PCR); branched DNA (bDNA), and nucleic acid sequence-based amplification assay (NASBA)
these technologies are used to amplify the extremely tiny virus so that it can be counted (PCR and NASBA use enzymes to amplify the RNA, bDNA uses branched DNA fragments to bind specifically to viral RNA).
Hope that helps! If you have any more questions, just ask :-)