Complete genome sequencing of Mycoplasma pneumoniae strain 309

M. pneumoniae 309 is a type 2a strain of this bacterium. Type 2a strain was rare in 1990s but is frequently found in clinical specimens after 2002 in Japan. This strain has variations in cytadhesin protein P1, which is the essential factor for pathogenesis. This variation is probably created by recombination events between p1 gene and repetitive sequences in the genome. This mechanism could be clearly understood by complete genome sequencing of 309 strain. The precise comparison of complete M. pneumoniae genomes also detect the differences of surface antigenic protein composition between 309 and other strains. This is the key information to understand the clinical emergence of type 2a strain.