Using spaceflight and spaceflight analogue culture for novel mechanistic insight into Salmonella pathogenesis

As the first bacterial pathogen to be profiled for changes in virulence in response to either spaceflight or spaceflight analogue culture, Salmonella enterica serovar Typhimurium (S. Typhimurium) has served as a model organism for evaluating the potential of these environments to alter the pathogenesis-related characteristics of microbes. This chapter describes a series of progressive studies conducted with S. Typhimurium that have established the paradigm that the low fluid shear environment present during spaceflight and spaceflight analogue culture (as well as in the infected host in vivo) could alter the virulence, pathogenesis-related stress responses, and global gene expression profiles of microbial pathogens like Salmonella. The exciting discovery that these environments could reprogram S. Typhimurium in a unique manner, thereby leading to the identification of entire classes of microbial genes/proteins involved in host interactions not previously identified under conventional culture conditions, laid the foundation for these experiments to be conducted with other microbial pathogens. Follow-up studies with other pathogens ultimately unveiled evolutionarily conserved responses to the microgravity and microgravity analogue environments, including the RNA chaperone Hfq, thus demonstrating that bacteria were "hard-wired" to respond to these conditions. These findings have important implications for astronaut health and hold potential for development of novel strategies for treatment and prevention for the general public.