Fig. 1From: Molecular epidemiology of Bordetella pertussis and analysis of vaccine antigen genes from clinical isolates from Shenzhen, ChinaThe minimum spanning tree of 50 Shenzhen stains. The size of the circle indicates the number of strains with this particular genotype. Each color represents one sample. The length of the connecting lines between the circles indicates the genetic distance between different genotypesBack to article page