Project description:Leptospirosis, caused by bacteria of the genus Leptospira, is a zoonotic disease affecting humans, companion animals, and all major livestock species. Typical propagation of the highly fastidious Leptospira borgepetesenii serovar Hardjo is limited to 29°C. However, newer culture media formulations now facilitate isolation and propagation at 37°C, a temperature that more closely emulates in vivo conditions and is hypothesized to regulate the expression of virulence factors during host infection. Since protein expression by leptospires is temperature dependent, and therefore the proteome of bacterin vaccines can differ whether grown at 37°C compared to 29°C, we compared the proteome of strains of Leptospira borgpetersenii serovar Hardjo at each temperature; two well-established strains that causes acute (strain JB197) or chronic asymptomatic disease (strain HB203) in the hamster challenge model of leptospirosis and two more recently isolated strains designated TC129 and TC273 (both of which cause chronic asymptomatic disease in the hamster). We found proteomic expression differences within strains propagated at the routine temperature of 29°C, and compared to the newly achieved culture temperature of 37°C. Results highlight significant differential protein expression, including virulence factors, amongst identical serovars of L. borgpetersenii when propagated at 29oC, the collective variation of which can be diminished when propagated at 37oC. Collectively, there is increasingly more evidence available to suggest bacterin vaccine design would benefit from consideration of strains employed, and potential effects of growth temperature related to specific behavior of pathogens in vaccine composition.