Genome-wide discovery of novel M1T1 group A streptococcal determinants important for fitness and virulence during soft-tissue infection

PLoS Pathogens

Jeffrey A. Freiberg¹  Yoann Le Breton²  Joshua Lieberman²  Ashton T. Belew²  Emrul Islam²  Najib M. El-Sayed³  Kevin S. McIver⁴  Hervé Tettelin⁴  Mark E. Shirtliff⁵  Ganesh S. Sundar⁶ 

[1] Center for Bioinformatics and Computational Biology, University of Maryland, College Park, Maryland, United States of America;Department of Cell Biology & Molecular Genetics and Maryland Pathogen Research Institute, University of Maryland, College Park, Maryland, United States of America;Department of Microbial Pathogenesis, Dental School, University of Maryland, Baltimore, Maryland, United States of America;Department of Microbiology and Immunology, University of Maryland School of Medicine, Baltimore, Maryland, United States of America;Division of Infectious Diseases, University of Maryland School of Medicine, Baltimore, Maryland, United States of America;Graduate Program in Life Sciences, University of Maryland School of Medicine, Baltimore, Maryland, United States of America

关键词: Mammalian genomics;    Genetic screens;    Soft tissue infections;    Genomic library screening;    Gene pool;    Group A streptococcal infection;    Skin infections;    Library screening;   

DOI  :  10.1371/journal.ppat.1006584

学科分类：生物科学（综合）

来源: Public Library of Science

【 摘 要 】

The Group A Streptococcus remains a significant human pathogen causing a wide array of disease ranging from self-limiting to life-threatening invasive infections. Epithelium (skin or throat) colonization with progression to the subepithelial tissues is the common step in all GAS infections. Here, we used transposon-sequencing (Tn-seq) to define the GAS 5448 genetic requirements for in vivo fitness in subepithelial tissue. A near-saturation transposon library of the M1T1 GAS 5448 strain was injected subcutaneously into mice, producing suppurative inflammation at 24 h that progressed to prominent abscesses with tissue necrosis at 48 h. The library composition was monitored en masse by Tn-seq and ratios of mutant abundance comparing the output (12, 24 and 48 h) versus input (T0) mutant pools were calculated for each gene. We identified a total of 273 subcutaneous fitness (scf) genes with 147 genes (55 of unknown function) critical for the M1T1 GAS 5448 fitness in vivo; and 126 genes (53 of unknown function) potentially linked to in vivo fitness advantage. Selected scf genes were validated in competitive subcutaneous infection with parental 5448. Two uncharacterized genes, scfA and scfB, encoding putative membrane-associated proteins and conserved among Gram-positive pathogens, were further characterized. Defined scfAB mutants in GAS were outcompeted by wild type 5448 in vivo, attenuated for lesion formation in the soft tissue infection model and dissemination to the bloodstream. We hypothesize that scfAB play an integral role in enhancing adaptation and fitness of GAS during localized skin infection, and potentially in propagation to other deeper host environments.

【 授权许可】

CC BY