Editing Measles virus (section)

== Genotypes ==
The measles virus genome is typically 15,894 nucleotides long and encodes eight proteins.<ref>{{cite journal |last1=Phan |first1=MVT |last2=Schapendonk |first2=CME |last3=Oude Munnink |first3=BB |last4=Koopmans |first4=MPG |last5=de Swart |first5=RL |last6=Cotten |first6=M |title=Complete Genome Sequences of Six Measles Virus Strains. |journal=Genome Announcements |date=29 March 2018 |volume=6 |issue=13 |doi=10.1128/genomeA.00184-18 |pmid=29599155 |pmc=5876482 }}</ref> The WHO currently recognises 8 [[clades]] of measles (A–H). Subtypes are designed with numerals—A1, D2 etc. Currently, 23 subtypes are recognised. The 450 nucleotides that code for the C‐terminal 150 amino acids of N are the minimum amount of sequence data required for genotyping a measles virus isolate. The genotyping scheme was introduced in 1998 and extended in 2002 and 2003.{{cn|date=August 2022}}

Despite the variety of measles genotypes, there is only one measles [[serotype]]. Antibodies to measles bind to the hemagglutinin protein. Thus, antibodies against one genotype (such as the [[Measles vaccine|vaccine strain]]) protect against all other genotypes.<ref>{{cite web |title=Measles |date=11 March 2013 |work=Biologicals — Vaccine Standardization |publisher=World Health Organization |url=https://www.who.int/biologicals/vaccines/measles/en/|archive-url=https://web.archive.org/web/20140501133047/http://www.who.int/biologicals/vaccines/measles/en/|url-status=dead|archive-date=1 May 2014}}</ref>

The major genotypes differ between countries and the status of measles circulation within that country or region. Endemic transmission of measles virus was interrupted in the United States and Australia by 2000 and the Americas by 2002.<ref>{{cite web|url=http://www.paho.org/hq/index.php?option=com_content&view=article&id=9318%3A2014-no-endemic-transmission-measles-americas-since-2002&catid=1443%3Aweb-bulletins&Itemid=135&lang=en|title=No endemic transmission of measles in the Americas since 2002|publisher=[[Pan American Health Organization]]|date=14 February 2017|access-date=11 September 2017}}</ref>