Differential responses of the antennal proteome of male and female migratory locusts to infection by a fungal pathogen.

The narrow host range entomopathogenic fungus, Metarhizium acridum, is an environmentally friendly acridid specific pathogen used for locust control. The locust is capable of responding within hours of infection, however, little is known concerning how the locust detects the pathogen. Here, we have identified 3213 proteins in the infected antennal proteome of the migratory locust, Locusta migratoria. iTRAQ comparative analyses of antennal proteomes identified 194 differentially abundant proteins (DAPs) between uninfected and infected males, 218 DAPs between uninfected and infected females, and 240 DAPs between infected males and infected females. In relation to olfaction, a total of 29 chemosensory proteins (CSPs), 9 odorant binding proteins (OBPs), 31 odorant receptors (ORs), and 8 ionotropic receptors (IRs) were differentially abundant after M. acridum infection, with a subset of 12 proteins found in both infected male and female antennae not present in uninfected individuals. The time course of the gene expression profiles of olfaction related DAPs were investigated by quantitative real-time PCR (qRT-PCR). Our data indicate significant changes in the antennal proteomes of male and female locusts in response to a microbial pathogen, highlighting the potential participation of olfactory processes in pathogen detection and response. BIOLOGICAL SIGNIFICANCE: The ability of an organism to detect microbial pathogens is essential for mounting a response to mitigate the spread of the infection. Using iTRAQ-based proteomic analyses changes in the protein repertoire of the antennae of male and female locusts in response to infection by a host-specific pathogen were determined. These data show proteomic alterations that are also sex-specific, identifying members of olfactory pathways that are modified in response to infection. Our data identify antennal and related olfactory proteins that are candidates for mediating host detection of pathogens, and that may contribute to subsequent behavioral and/or immune responses of the host to the infection challenge.