Low-shear modelled microgravity alters expression of virulence determinants by Staphylococcus aureus
- Paper number
IAC-08.A1.7.-A2.7.5
- Author
Ms. Helena Rosado, School of Pharmacy, University of London, United Kingdom
- Coauthor
Dr. Marie Doyle, School of Pharmacy, University of London, United Kingdom
- Coauthor
Dr. Jason Hinds, United Kingdom
- Coauthor
Prof. Peter W. Taylor, School of Pharmacy, University of London, United Kingdom
- Year
2008
- Abstract
Microbiological monitoring of air and surfaces within the ISS indicated that bacteria of the genus Staphylococcus are found with high frequency. Staphylococcus aureus, an opportunistic pathogen with the capacity to cause severe debilitating infection, constitutes a significant proportion of these isolates. Ground-based studies of Salmonella enterica have provided evidence that bacterial virulence is increased under the influence of simulated microgravity. These studies, and others linking space flight to reduced immune competence, provide clear evidence that extended missions may be compromised by increased risk of infection. We have therefore examined the effects of simulated microgravity on the virulence properties of S. aureus. The methicillin-susceptible S. aureus isolates RF1, RF6 and RF11 were grown in a Synthecon High Aspect Ratio Vessel (HARV) under low shear modelled microgravity (LSMMG) and compared with cells grown under normal gravity (NG). Global gene expression was determined by DNA microarray analysis and protein secretion examined using two-dimensional gel electrophoresis. Growth in a modelled microgravity environment had an impact on a number of factors associated with the virulence of S. aureus. LSMMG elicited large reductions in protein secretion by the three isolates; in particular isolate RF6 displayed a four-fold reduction in protein secretion. In total, 40 proteins were found to be down-regulated under LSMMG in a highly reproducible fashion. LC-MS/MS identified these proteins to be involved mainly with cell metabolism, including protein biosynthesis, folding and transport; 4 proteins were also found to be iron-binding proteins. DNA microarray identified significant changes in gene regulation; these were in the main associated with cell metabolism, transport, stress and virulence. For isolate RF6, the expression of a major virulence gene, hla, and the virulence regulatory system saeR/ saeS was found to be reduced two-fold. These data provide strong evidence that growth of S. aureus under modelled microgravity leads to a reduction in expression of virulence determinants.
- Abstract document
- Manuscript document
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