Editing Virology (section)

===Polymerase chain reaction (PCR) and other nucleic acid detection methods===
PCR is a mainstay method for detecting viruses in all species including plants and animals. It works by detecting traces of virus specific RNA or DNA. It is very sensitive and specific, but can be easily compromised by contamination. Most of the tests used in veterinary virology and medical virology are based on PCR or similar methods such as [[transcription mediated amplification]]. When a novel virus emerges, such as the covid coronavirus, a specific test can be devised quickly so long as the viral genome has been sequenced and unique regions of the viral DNA or RNA identified.<ref name="pmid32815744">{{cite journal |vauthors=Zhu H, Zhang H, Xu Y, Laššáková S, Korabečná M, Neužil P |title=PCR past, present and future |journal=BioTechniques |volume=69 |issue=4 |pages=317–325 |date=October 2020 |pmid=32815744 |pmc=7439763 |doi=10.2144/btn-2020-0057 |url=}}</ref> The invention of [[microfluidic]] tests as allowed for most of these tests to be automated,<ref name="pmid35300739">{{cite journal |vauthors=Wang X, Hong XZ, Li YW, Li Y, Wang J, Chen P, Liu BF |title=Microfluidics-based strategies for molecular diagnostics of infectious diseases |journal=Military Medical Research |volume=9 |issue=1 |pages=11 |date=March 2022 |pmid=35300739 |pmc=8930194 |doi=10.1186/s40779-022-00374-3 |url= |doi-access=free }}</ref> Despite its specificity and sensitivity, PCR has a disadvantage in that it does not differentiate infectious and non-infectious viruses and "tests of cure" have to be delayed for up to 21 days to allow for residual viral nucleic acid to clear from the site of the infection.<ref name="pmid33219449">{{cite journal |vauthors=Benzigar MR, Bhattacharjee R, Baharfar M, Liu G |title=Current methods for diagnosis of human coronaviruses: pros and cons |journal=Analytical and Bioanalytical Chemistry |volume=413 |issue=9 |pages=2311–2330 |date=April 2021 |pmid=33219449 |pmc=7679240 |doi=10.1007/s00216-020-03046-0 |url=}}</ref>