The reproductive status of the host determines the tolerance and resistance toMycobacterium marinuminfection inDrosophila melanogaster

Abstract

Both the sex and the reproductive status of the host have a major impact on the regulation of the immune response against infection. The fruit fly Drosophila melanogaster has become a powerful model for study such interaction due to its well-characterized hormonal, metabolic and immune traits. In order to further characterize this in mycobacterial infections, we tested the systemic Mycobacterium marinum infection of D. melanogaster. We wanted to understand whether the sex or the reproductive status has an impact on the tolerance or resistance of the host to the infection. We measured gene expression by RT-qPCR of immune genes (diptericin and drosomycin) as well as host survival and bacillary load at time of death. We assessed the impact of metabolic (by expression of upd3 and impl2) and hormonal (by ecR expression) regulation in the protection against infection. Data showed that the effect of reproductive status (virgin and mated kept alone or together) in tolerance and resistance to infection is sex dependent. We found differences in protection according to the levels of expression in immune, metabolic and hormone-related genes which also showed differences between sex and reproductive status, highlighting the expression of impl2 in males and upd3 in females to face the infection. The results obtained allows further interpretation of the results when assessing the differences between sexes in D. melanogaster for other infections, since data demonstrated the importance of the reproductive status in resistance and tolerance against M. marinum infection.