Transcriptional analysis shows a robust host response to Toxoplasma gondii during early and late chronic infection in both male and female mice

Abstract

The long-term host effects caused by the protozoan parasite Toxoplasma gondii are poorly understood. RNA-seq analysis previously determined that the host response in the brain was higher and more complex at 28 versus 10 days postinfection. Here, we analyzed the host transcriptional profile of age-and sex-matched mice during early (21 and 28 days) and late (3 and 6 months) chronic infection. We found that a majority of the host genes which increase in abundance at day 21 postinfection are still increased 6 months postinfection for both male and female mice. While most of the differentially expressed genes were similar between sexes, females have far fewer genes that are significantly less abundant, which may lead to the slight increased cyst burden in males. Transcripts for C-X-C Motif Chemokine Ligand 13 (CXCL13) and a C-C Motif Chemokine Receptor 2 (CCR2) were significantly higher in females compared to males during infection. As T. gondii chronic infection and profilin (PRF) confer resistance to Listeria monocytogenes infection in a CCR2 dependent manner, the sex specific difference in CCR2 expression lead us to re-test the protection of PRF in both sexes. Chronic infection as well as PRF were nearly as effective at reducing the bacterial burden in male versus female mice. These data show that most of the differentially express host genes are similar between males and females, important differences exist leading us to emphasize the inclusion of both sexes for future studies.