Poly-N-acetylglucosamine production in Staphylococcus aureus is essential for virulence in murine models of systemic infection.
The contribution of the Staphylococcus aureus surface polysaccharide poly-N-acetylglucosamine (PNAG) to virulence was evaluated in three mouse models of systemic infection: bacteremia, renal abscess formation, and lethality following high-dose intraperitoneal (i.p.) infection. Deletion of the intercellular adhesin (ica) locus that encodes the biosynthetic enzymes for PNAG production in S. aureus strains Mn8, Newman, and NCTC 10833 resulted in mutant strains with significantly reduced abilities to maintain bacterial levels in blood following intravenous or i.p. injection, to spread systemically to the kidneys following i.p. injection, or to induce a moribund/lethal state following i.p. infection. In the bacteremia model, neither growth phase nor growth medium used to prepare the S. aureus inoculum affected the conclusion that PNAG production was needed for full virulence. As the SarA regulatory protein has been shown to affect ica transcription, PNAG synthesis, and biofilm formation, we also evaluated S. aureus strains Mn8 and 10833 deleted for the sarA gene in the renal infection model. A decrease in PNAG production was seen in sarA mutants using immunoblots of cell surface extracts but was insufficient to reduce the virulence of sarA-deleted strains in this model. S. aureus strains deleted for the ica genes were much more susceptible to antibody-independent opsonic killing involving human peripheral blood leukocytes and rabbit complement. Thus, PNAG confers on S. aureus resistance to killing mediated by these innate host immune mediators. Overall, PNAG production by S. aureus appears to be a critical virulence factor as assessed in murine models of systemic infection.
Kropec
Andrea
A
Channing Laboratory, Department of Medicine, Brigham and Women's Hospital, Boston, Massachusetts 02115, USA.
Maira-Litran
Tomas
T
Jefferson
Kimberly K
KK
Grout
Martha
M
Cramton
Sarah E
SE
Götz
Friedrich
F
Goldmann
Donald A
DA
Pier
Gerald B
GB
D018829:Adhesins, Bacterial / Q000235:genetics; D000818:Animals; D016470:Bacteremia / Q000276:immunology / Q000382:microbiology*; D001426:Bacterial Proteins / Q000235:genetics*; D004195:Disease Models, Animal; D017353:Gene Deletion; D007113:Immunity, Innate / Q000276:immunology; D051379:Mice; D010587:Phagocytosis; D013203:Staphylococcal Infections / Q000276:immunology / Q000382:microbiology*; D013211:Staphylococcus aureus / Q000235:genetics / Q000378:metabolism / Q000472:pathogenicity*; D014774:Virulence / Q000235:genetics; D047071:beta-Glucans / Q000737:chemistry / Q000276:immunology*
D018829:Adhesins, Bacterial; D001426:Bacterial Proteins; C492107:SarA protein, Staphylococcus aureus; C048165:adhesin, Staphylococcus aureus; D047071:beta-Glucans; C505465:poly-N-acetyl-1-6-glucosamine