Identification of CiaR Regulated Genes That Promote Group B Streptococcal Virulence and Interaction with Brain Endothelial Cells.
Group B Streptococcus (GBS) is a major causative agent of neonatal meningitis due to its ability to efficiently cross the blood-brain barrier (BBB) and enter the central nervous system (CNS). It has been demonstrated that GBS can invade human brain microvascular endothelial cells (hBMEC), a primary component of the BBB; however, the mechanism of intracellular survival and trafficking is unclear. We previously identified a two component regulatory system, CiaR/H, which promotes GBS intracellular survival in hBMEC. Here we show that a GBS strain deficient in the response regulator, CiaR, localized more frequently with Rab5, Rab7 and LAMP1 positive vesicles. Further, lysosomes isolated from hBMEC contained fewer viable bacteria following initial infection with the ΔciaR mutant compared to the WT strain. To characterize the contribution of CiaR-regulated genes, we constructed isogenic mutant strains lacking the two most down-regulated genes in the CiaR-deficient mutant, SAN_2180 and SAN_0039. These genes contributed to bacterial uptake and intracellular survival. Furthermore, competition experiments in mice showed that WT GBS had a significant survival advantage over the Δ2180 and Δ0039 mutants in the bloodstream and brain.
Department of Biology and Center for Microbial Sciences, San Diego State University, San Diego, California, 92182, United States of America.
Rong
R
Mu
Department of Biology and Center for Microbial Sciences, San Diego State University, San Diego, California, 92182, United States of America.
Andrew S
AS
Cutting
Department of Biology and Center for Microbial Sciences, San Diego State University, San Diego, California, 92182, United States of America.
Yvette
Y
Del Rosario
Department of Biology and Center for Microbial Sciences, San Diego State University, San Diego, California, 92182, United States of America.
Nicholas
N
Villarino
Department of Biology and Center for Microbial Sciences, San Diego State University, San Diego, California, 92182, United States of America.
Lara
L
Stewart
Department of Biology and Center for Microbial Sciences, San Diego State University, San Diego, California, 92182, United States of America.
Thomas A
TA
Weston
Department of Biology and Center for Microbial Sciences, San Diego State University, San Diego, California, 92182, United States of America.
Kathryn A
KA
Patras
Department of Biology and Center for Microbial Sciences, San Diego State University, San Diego, California, 92182, United States of America.|Department of Pediatrics, University of California San Diego School of Medicine, La Jolla, California, 92093, United States of America.
Kelly S
KS
Doran
D000818:Animals; D001422:Bacterial Adhesion / Q000276:immunology*; D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism; D001692:Biological Transport; D001812:Blood-Brain Barrier; D001921:Brain / Q000276:immunology* / Q000378:metabolism / Q000382:microbiology / Q000473:pathology; D002465:Cell Movement; D002478:Cells, Cultured; D004730:Endothelium, Vascular / Q000276:immunology* / Q000378:metabolism / Q000382:microbiology / Q000473:pathology; D005455:Fluorescent Antibody Technique; D015964:Gene Expression Regulation, Bacterial / Q000235:genetics; D005809:Genes, Regulator; D006801:Humans; D007113:Immunity, Innate / Q000276:immunology; D008297:Male; D051379:Mice; D009154:Mutation / Q000235:genetics; D011494:Protein Kinases / Q000235:genetics / Q000378:metabolism*; D013290:Streptococcal Infections / Q000235:genetics / Q000276:immunology / Q000382:microbiology*; D013292:Streptococcus agalactiae / Q000472:pathogenicity*; D014774:Virulence / Q000235:genetics / Q000276:immunology*
D001426:Bacterial Proteins; D011494:Protein Kinases; C088910:CiaR protein, Streptococcus pneumoniae