%A Qin,Tian %A Zhou,Haijian %A Ren,Hongyu %A Liu,Wenbin %D 2017 %J Frontiers in Microbiology %C %F %G English %K secretion systems,Legionella,L. pneumophila,whole genome sequence,population structure,pathogenicity evolution %Q %R 10.3389/fmicb.2017.00388 %W %L %M %P %7 %8 2017-March-14 %9 Original Research %+ Tian Qin,State Key Laboratory for Infectious Disease Prevention and Control, National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention,Beijing, China,qintian@icdc.cn %+ Tian Qin,Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases,Hangzhou, China,qintian@icdc.cn %# %! Secretion systems of Legionella %* %< %T Distribution of Secretion Systems in the Genus Legionella and Its Correlation with Pathogenicity %U https://www.frontiersin.org/articles/10.3389/fmicb.2017.00388 %V 8 %0 JOURNAL ARTICLE %@ 1664-302X %X The genus Legionella comprises over 60 species, which are important human pathogens. Secretion systems in Legionella pneumophila have been studied extensively because of the essential role of protein secretion in bacterial infection. However, there are few reports describing the secretion systems in non-L. pneumophila species. In this study, we analyzed the distribution of secretion systems in L. pneumophila and 18 species of non-L. pneumophila based on whole genome sequences. A total of 74 whole genome sequences from 19 species of Legionella were analyzed. Type II and IVB secretion systems were detected in all Legionella strains, but the type I secretion systems was restricted to L. pneumophila. The type IVA secretion system was randomly distributed among different species. Furthermore, we found the type VI secretion system in three non-L. pneumophila strains (Legionella cherrii DSM 19213, Legionella dumoffii Tex-KL, and Legionella gormanii ATCC 33297). In population structure analysis, L. pneumophila formed a conservative cluster and was located at the terminal of the evolutionary tree. At the same time, L. pneumophila, especially eight clone groups (named MCGG1–MCGG8), showed higher intracellular growth ability than non-L. pneumophila species. These results suggest that L. pneumophila has acquired additional secretion systems during evolution, resulting in increased pathogenicity.