TEMPORAL AND GEOGRAPHICAL-DISTRIBUTION OF MEASLES-VIRUS GENOTYPES

The nucleotide sequence encoding the C terminus of the nucleocapsid pr otein of measles virus (MV) is the most variable in the genome. The se quence of this region is reported for 21 new MV strains and for virus RNA obtained from cases of subacute panencephalitis (SSPE) tissue. The nucleotide sequence of a total of 65 MV strains has been analysed usi ng the CLUSTAL program to determine the relationships between the stra ins. An unrooted tree shows that eight different genotypes can be disc erned amongst the sequences analysed so far. The data show that the C- terminal coding sequence of the nucleocapsid gene, although highly var iable between strains, is stable in a given strain and does not appear to diverge in tissue culture, It therefore provides a good 'signature ' sequence for specific genotypes. The sequence of this region can be used to discriminate new imported viruses from old 'endemic' strains o f MV in a geographical area. The different genotypes are not geographi cally restricted although some appear to be the mainly 'endemic' types in large areas of the world. In global terms there appears to be at l east four cocirculating genotypes of MV. The low level of divergence i n the Edmonston lineage group isolated before 1970 indicates that some isolates are probably laboratory contaminants. This applies to some S SPE isolates such as the Halle, Mantooth and Horta-Barbosa strains as well as some wild-type isolates from that period.