Expression of Bacillus cereus Virulence-Related Genes in an Ocular Infection-Related Environment

• Published in: Microorganisms (Basel) Vol. 8; no. 4; p. 607
• Main Authors: Coburn, Phillip S, Miller, Frederick C, Enty, Morgan A, Land, Craig, LaGrow, Austin L, Mursalin, Md Huzzatul, Callegan, Michelle C
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 22-04-2020; MDPI
• Subjects: Antibiotics; Bacillus cereus; Chemotaxis; Endophthalmitis; Eye; Gene expression; Genes; Infections; Inflammation; Laboratories; Levels; Motility; ocular environment; ocular infections; Pathogenesis; Pathogens; Phenotypes; Pre-eclampsia; Regulators; Ribonucleic acid; RNA; Superoxide dismutase; Toxins; Virulence; virulence determinants; vitreous; Vitreous humor; Vitreous humour; United States > US; virulence determinants; vitreous; ocular environment; Bacillus cereus; endophthalmitis; ocular infections
• ISSN: 2076-2607; 2076-2607
• DOI: 10.3390/microorganisms8040607

produces many factors linked to pathogenesis and is recognized for causing gastrointestinal toxemia and infections.
also causes a fulminant and often blinding intraocular infection called endophthalmitis. We reported that the PlcR/PapR system regulates intraocular virulence, but the specific factors that contribute to
virulence in the eye remain elusive. Here, we compared gene expression in ex vivo vitreous humor with expression in Luria Bertani (LB) and Brain Heart Infusion (BHI) broth by RNA-Seq. The expression of several cytolytic toxins in vitreous was less than or similar to levels observed in BHI or LB. Regulators of virulence genes, including PlcR/PapR, were expressed in vitreous. PlcR/PapR was expressed at low levels, though we reported that PlcR-deficient
was attenuated in the eye. Chemotaxis and motility genes were expressed at similar levels in LB and BHI, but at low to undetectable levels in vitreous, although motility is an important phenotype for
in the eye. Superoxide dismutase, a potential inhibitor of neutrophil activity in the eye during infection, was the most highly expressed gene in vitreous. Genes previously reported to be important to intraocular virulence were expressed at low levels in vitreous under these conditions, possibly because in vivo cues are required for higher level expression. Genes expressed in vitreous may contribute to the unique virulence of
endophthalmitis, and future analysis of the
virulome in the eye will identify those expressed in vivo, which could potentially be targeted to arrest virulence.