Figure 1. Acquisition of new tbpB genes by subgroup III Neisseria meningitidis during epidemic spread.

Colours indicate the family of each tbpB allele, with red corresponding to family 4, green corresponding to family 1, and blue corresponding to family 3. The bars highlight the time frame, most common tbpB type, and geographical extent of each epidemic (in 1987, pilgrims from the Hajj pilgrimage briefly distributed the lineage worldwide). The circles correspond to variant genotypes. Small circles indicating that the variant allele was found in only one strain; large circles indicate it was found in between two and four strains.