Editing Virology (section)

===Serology===
Viruses are [[antigens]] that induce the production of [[antibodies]] and these antibodies can be used in laboratories to study viruses. Related viruses often react with each other's antibodies and some viruses can be named based on the antibodies they react with. The use of the antibodies which were once exclusively derived from the serum (blood fluid) of animals is called [[serology]].<ref name="pmid32342927">{{cite journal |vauthors=Zainol Rashid Z, Othman SN, Abdul Samat MN, Ali UK, Wong KK |title=Diagnostic performance of COVID-19 serology assays |journal=The Malaysian Journal of Pathology |volume=42 |issue=1 |pages=13–21 |date=April 2020 |pmid=32342927 |doi= |url=}}</ref> Once an antibody–reaction has taken place in a test, other methods are needed to confirm this. Older methods included [[complement fixation test]]s,<ref name="pmid1365549">{{cite journal |vauthors=Swack NS, Gahan TF, Hausler WJ |title=The present status of the complement fixation test in viral serodiagnosis |journal=Infectious Agents and Disease |volume=1 |issue=4 |pages=219–24 |date=August 1992 |pmid=1365549 |doi= |url=}}</ref> [[Hemagglutination assay|hemagglutination inhibition]] and [[Neutralizing antibody|virus neutralisation]].<ref name="pmid21887208">{{cite journal |vauthors=Smith TJ |title=Structural studies on antibody recognition and neutralization of viruses |journal=Current Opinion in Virology |volume=1 |issue=2 |pages=150–6 |date=August 2011 |pmid=21887208 |pmc=3163491 |doi=10.1016/j.coviro.2011.05.020 |url=}}</ref> Newer methods use [[ELISA|enzyme immunoassay]]s (EIA).<ref name="pmid22185616">{{cite journal |vauthors=Mahony JB, Petrich A, Smieja M |title=Molecular diagnosis of respiratory virus infections |journal=Critical Reviews in Clinical Laboratory Sciences |volume=48 |issue=5–6 |pages=217–49 |date=2011 |pmid=22185616 |doi=10.3109/10408363.2011.640976 |s2cid=24960083 |url=}}</ref>

In the years before [[Polymerase chain reaction|PCR]] was invented [[immunofluorescence]] was used to quickly confirm viral infections. It is an infectivity assay that is virus species specific because antibodies are used. The antibodies are tagged with a dye that is luminescencent and when using an optical microscope with a modified light source, infected cells glow in the dark.<ref name="pmid32197545">{{cite journal |vauthors=AbuSalah MA, Gan SH, Al-Hatamleh MA, Irekeola AA, Shueb RH, Yean Yean C |title=Recent Advances in Diagnostic Approaches for Epstein-Barr Virus |journal=Pathogens |volume=9 |issue=3 |date=March 2020 |page=226 |pmid=32197545 |pmc=7157745 |doi=10.3390/pathogens9030226 |url=|doi-access=free }}</ref>