Although measles virus (MV) is serologically monotypic, the
genetic characterization of wild-type viruses has identified
eight clades (A – H), which have been divided into 22
genotypes and one proposed genotype. Clades B, C, D, G and H
each contain multiple genotypes (B1 - 3, C1 - 2, D1 - 10, G1
- 3, H1 - 2) while clades A, E and F each contain a single genotype
(A, E, F). The sequences of the vaccine strains indicate that
the wild type viruses from which they were derived were all
members of genotype A.
There are no known biological differences between viruses of
different genotypes. Specific measles genotypes are not associated
with differences in severity of disease, likelihood of developing
severe sequela such as subacute sclerosing panencephalitis or
inclusion body encephalitis, or variability in sensitivity of
laboratory diagnosis.
Analysis of the variability in the nucleotide sequences of wild-type
MVs has enabled the use of molecular epidemiologic techniques
for measles surveillance. Genetic characterization of viral
isolates or RT-PCR products is the only laboratory test that
can differentiate between vaccine-associated cases and wild-type
infection.
In 1998, the World Health Organization (WHO) recommended a standard
protocol for the designation of measles genotypes. The minimum
amount of sequence data required to assign a virus to a genotype
are the 450 nucleotides encoding the carboxy terminus of the
N protein. The entire sequence of the coding region of the H
gene should be obtained from representative isolates
The purpose of this summary is to collate all available reports
of MV genotypes and to standardize the published genotype nomenclature,
according to the current WHO criteria, with the aim of giving
a comprehensive overview of the distribution of MV genotypes
in the prevaccine and postvaccine eras
Summary of distribution of MV genotypes from the prevaccine
era to 2004
Refer to “Review of global
temporal and geographical distribution of measles virus genotypes.pdf”
for complete referencing of data shown in figure
Data reflects publications available as of
August 2005
