Genotypes
The WHO currently recognises 8 clades of measles (A - H). Subtypes are designed with numerals - A1, D2 etc. Currently a total of 23 subtypes are recognised. The sequencing of 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.
The major genotypes differ between countries and restatus of measles circulation within that country or region. Indigenous transmission of measles virus was interrupted in the United States and Australia by 2000 and the Americas by 2002.
Read more about this topic: Measles