Editing Viral load (section)

===Nucleic acid-based tests (NATs)===

There are many different molecular based test methods for quantifying the viral load using NATs. The starting material for amplification can be used to divide these molecular methods into three groups:<ref>{{cite book|last1=Buckingham|first1=L.|last2=Flaws|first2=M.L.|date=2007|title=Molecular Diagnostics Fundamentals, Methods, & Clinical Applications|url=http://www.justmed.eu/files/MolecularDiagnosticsFundamentalsMethodsandClinicalApplications.pdf|publisher=F.A. Davis Company|pages=121–154|isbn= 978-0-8036-1659-2|access-date=7 September 2020}}</ref>
# Target amplification which uses the nucleic acid itself. Just a few of the more common methods
#* The [[polymerase chain reaction]] (PCR) method of [[in vitro]] DNA synthesis uses a [[DNA]] template, [[polymerase]], buffers, [[Primer (molecular biology)|primers]], and [[nucleotides]] to multiply the HIV in the blood sample. Then a chemical reaction marks the virus. The markers are measured and used to calculate the amount of virus.  PCR is used to quantify [[Integrase|integrated]] DNA.
#* [[Reverse transcription polymerase chain reaction]] (RT-PCR) is a variation of PCR that can be used to quantify viral RNA. RNA is used as the starting material for this method and converted to double-stranded DNA, using the enzyme [[reverse transcriptase]] (RT) for PCR.
#* The [[NASBA (molecular biology)|nucleic acid sequence-based amplification]] (NASBA) method is a transcription-based amplification system (TAS) variation of PCR. RNA is used as the target and a DNA copy is made. The DNA copy is then transcribed into RNA and amplified. Several TAS commercial variations are available including; transcription-mediated amplification (TMA), and self-sustaining sequence replication (3SR).
# [[Molecular probe|Probe]] specific amplification uses synthetic probes that preferentially bind to a target sequence. The probes are then amplified
# Signal amplification uses large amounts of signal bound to an unamplified target originally present in the sample. One commonly used method:
#* The [[Branched DNA assay|branched DNA]] (bDNA) method can use either DNA or RNA as the target nucleic acid. Short probes attached to a solid support and capture the target nucleic acid. Additional extender probes also bind to the target nucleic acid and to numerous reporter molecules which are used to increase the signal intensity, which is converted to a viral count.