Figure 1. Phylogenetic tree including genotype B2 and genotype B3 of measles virus (MV) strains from the Democratic Republic of the Congo 2000–2006, and World Health Organization (WHO) reference strains (italics) of the corresponding genotypes and some other genotype B2 strains available in GenBank (accession numbers in brackets). MV strains were named according to WHO nomenclature: MVi/City of isolation.Country/epidemiologic week.year of isolation/isolate number. Sequences obtained from RNA extracted from isolates (MVi) or clinical material (MVs) were distinguished. The main genotype B2 variants from Kinshasa (B2KIN-A, B2KIN-B, and B2KIN-C) are indicated in boldface. Except for B2 strains from Kinshasa, the provinces of Democratic Republic of the Congo where strains were collected are indicated in brackets. The phylogenetic tree was calculated on the basis of the 450-nt region that codes for the C-terminus of the MV N protein by using MEGA4 software (24) and the neighbor-joining method (Kimura 2-parameter, 1,000 bootstraps). Scale bar indicates nucleotide substitutions per site.