title: Differential bacterial gene expression during experimental pneumococcal endophthalmitis.
abstract: Streptococcus pneumoniae (pneumococcus) is a potential cause of bacterial endophthalmitis in humans that can result in ocular morbidity. We sought to identify pneumococcal genes that are differentially expressed during growth in the vitreous humor of the eye in an experimental endophthalmitis model. Microarray analysis was used to identify genes that were differentially expressed when pneumococci replicated in the vitreous of rabbit eyes as compared with bacteria grown in vitro in Todd Hewitt medium. Array results were verified by quantitative real-time PCR analysis of representative genes. Select genes potentially playing a role in virulence during endophthalmitis were deleted, and mutants were tested for reduced eye pathogenesis and altered adhesion to host cells. Array analysis identified 134 genes that were differentially expressed during endophthalmitis; 112 genes demonstrated increased expression during growth in the eye whereas 22 were downregulated. Real-time analysis verified increased expression of neuraminidase A (NanA; SP1693), neuraminidase B (NanB; SP1687) and serine protease (SP1954), and decreased expression of RlrA (SP0461) and choline transporter (SP1861). Mutation of NanA and NanB had no major effect on pathogenesis. Loss of SP1954 led to increased adherence to host cells. S. pneumoniae enhances and represses the expression of a variety of genes during endophthalmitis. While some of these genes reflect changes in metabolic requirements, some appear to play a role in immune evasion and pathogenesis in the eye.
authors: Department of Biological Sciences, Mississippi State University, Starkville, Miss., USA.
authors: Justin A
authors: JA
authors: Thornton
authors: Nathan A
authors: NA
authors: Tullos
authors: Melissa E
authors: ME
authors: Sanders
authors: Granger
authors: G
authors: Ridout
authors: Yong-Dong
authors: YD
authors: Wang
authors: Sidney D
authors: SD
authors: Taylor
authors: Larry S
authors: LS
authors: McDaniel
authors: Mary E
authors: ME
authors: Marquart
mesh_terms: D000818:Animals; D001426:Bacterial Proteins / Q000378:metabolism; D004195:Disease Models, Animal; D009877:Endophthalmitis / Q000378:metabolism* / Q000382:microbiology; D015818:Eye Infections, Bacterial / Q000378:metabolism* / Q000382:microbiology; D020869:Gene Expression Profiling; D005798:Genes, Bacterial; D046228:Microarray Analysis; D011008:Pneumococcal Infections / Q000378:metabolism* / Q000382:microbiology; D011817:Rabbits; D060888:Real-Time Polymerase Chain Reaction; D013296:Streptococcus pneumoniae / Q000235:genetics* / Q000378:metabolism; D014822:Vitreous Body / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins