Figure 2.

Phylogenetic tree based on a 450-nt region of the N gene of measles virus created using the Kimura 2-parameter model and the neighbor-joining algorithm of MEGA 5.05. Only bootstrap values ≥70% (1000 replicates) are shown. Bulgarian sequences are named based on the location, epidemiological week, and year. The sequences obtained during the present study are marked with black dots, and reference sequences are defined by accession number, name, and genotype. Bulgarian sequences from the period 2013-2017 are noted according to the year (2013: black circle, 2016: black triangle, 2017: gray rhombus). In the GenBank, we found identical strains from other countries, and reference sequences were determined by accession number, name and genotype.