Transcriptomic signatures of disease tolerance and environmental persistence in a mosquito-microsporidian system

Parasite life histories are expected to shape virulence and transmission, but the host programmes involved are largely unknown. Experimental evolution and RNA-seq were combined in a mosquito-nicrosporidian system, Anopheles gambia e- Vavraia culicis, to test how evolved parasite strategies alter host gene expression. A mosquito population was infected with parasite lineages selected for early or late transmission and compared with infections by an unselected reference parasite and with uninfected controls. Whole-body transcriptomes were all sampled at a common sporulating stage of infection. A core infection signature was identified by contrasting reference infections with uninfected mosquitoes. Against this baseline, early and late parasites generated distinct, partly overlapping expression profiles. Network analysis revealed modules whose activity tracked infection background and estimates of virulence and parasite load. One module was negatively associated with virulence and enriched for genes involved in damage limitation and tissue integrity, consistent with a disease tolerance programme. A second was positively associated with environmental persistence and enriched for genes that condition the replication and release environment, indicating that host pathways can influence the robustness of transmission stages. These findings link parasite life history, host tolerance and environmental persistence and highlight molecular targets for eco-evolutionary studies of vector-borne disease.