Task Progress:
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Understanding the impact of the spaceflight environment on the virulence potential of a wide variety of microorganisms is critical for ensuring crew health, safety, and performance. Changes that occur to both the immune system of astronauts and pathogenesis of microbes during spaceflight could represent a formidable challenge to the successful transition from short-to-long duration missions. The goal of this work was to assess the feasibility of using the roundworm Caenorhabditis elegans (C. elegans) as a model host organism for investigating transient changes in virulence of microbes cultured under spaceflight analogue conditions in the Rotating Wall Vessel (RWV) bioreactor. The design of this study was such that only the bacteria were cultured in the RWV, while the C. elegans hosts (wild type and an immunocompromised mutant) were grown prior to infection on standard nematode growth media (NGM) agar plates on their normal laboratory diet of Escherichia coli OP50. The infections then took place in liquid medium using a variety of exposure times (1-18 hours) in order to minimize any reversion of the low-shear modeled microgravity (LSMMG)-associated phenotypes (i.e., changes in virulence and pathogenesis-related stress resistance) during the infection. Microorganisms profiled in this work included: 1) Salmonella enterica serovar Typhimurium, 2) Staphylococcus aureus, and 3) an ISS potable water isolate of Burkholderia cepacia.
Under the conditions of this study, we found that transient exposure of the RWV-cultured microbes to C. elegans in a static dish was not sufficient for establishing a lethal infection in the nematode relative to the uninfected control nematodes fed on OP50. The outcomes of the infection process in liquid were quite different from what was previously reported for these pathogens using a solid agar medium. This indicates the need for further study design optimization. Persistence studies with S. Typhimurium did however indicate an early difference in the bacterial colonization numbers within the nematode intestine infected with LSMMG versus control cultures. We also observed an interesting phenotype following S. aureus infection, in which the bacterium appeared to form a biofilm-like structure around the anterior of the worm in liquid. Studies are ongoing to further investigate these findings.
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Abstracts for Journals and Proceedings
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Castro SL, Nickerson CA, Ott CM, Forsyth RJ, Rideout A, Alverdy JC, Barrila J. "Evaluating the Spaceflight Infectious Disease Risk Potential of Pathogenic and Commensal microorganisms using Caenorhabditis elegans as a Human Surrogate Model for Infection." Presented at the 2014 Human Research Program Investigators’ Workshop, Galveston, TX, February 12-13, 2014. 2014 Human Research Program Investigators’ Workshop, Galveston, TX, February 12-13, 2014. Immunology and Microbiology Posters, http://www.hou.usra.edu/meetings/hrp2014/pdf/3267.pdf , Feb-2014
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Abstracts for Journals and Proceedings
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Barrila J, Ott CM, Forsyth RJ, Davis R, Wilson JW, Nickerson CA. "Experimental Considerations for the Proper Assessment of Spaceflight-induced alterations in Microbial Virulence " 30th Annual Meeting of the American Society for Gravitational and Space Research, Pasadena, CA, October 22-26, 2014. 30th Annual Meeting of the American Society for Gravitational and Space Research, Pasadena, CA, October 22-26, 2014. Abstract number IP.32. , Oct-2014
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Awards
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Barrila J. "2014 Thora W. Halstead Young Investigator's Award, American Society for Gravitational and Space Research, October 2014." Oct-2014
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