Bats are unique both ecologically and physiologically, and can thrive in challenging seasonal environments. Despite their role in zoonoses, bat immunology and disease ecology are relatively poorly understood. We have demonstrated that the highly social and peri-domestic African fruit bat Epomophorus labiatus, which may play a role in Filovirus disease ecology, hosts high levels of the malarial parasite Hepatocystis year-round. Our data show that infection load (percent RBCs infected) is significantly correlated to electrolyte imbalance, thus potentially compromising the bat’s overall health status. We will explore the hypothesis that being constitutively infected with one pathogen (Hepatocystis) is correlated with changes in antiviral immunity and overall bat health. For this study, Hepatocystis infection levels were quantified by scanning blood smears and by measuring levels of parasite transcripts by 3’-TagSeq next generation sequencing transcriptomic gene expression analysis in liver tissue from 100 little epauletted fruit bats. Host and parasite gene expression was measured by mapping the 3’-TagSeq data against a high quality de novo transcriptome assembly generated from deep-sequencing RNASeq of spleen and liver. Weighted correlation network analysis (WGCNA) will be used to explore relationships between the level of parasite infection with host gene expression profiles during bat life history stages. Host-parasite interactions will be characterized by identifying clusters (pathways) of highly correlated genes.
Results/Conclusions
We present evidence that some intrinsic and extrinsic factors, such as season, reproductive status, and parasitic infection, influence bat health as well as immune and metabolic gene expression in a way that may affect fitness and survivorship. Demonstration of an altered immune gene expression profile in those bats with higher Hepatocystis prevalence coupled with impacted bat health may provide insight into how these fruit bats are successful viral reservoir hosts. This may then contribute to seasonal infection dynamics by affecting viral load and the viral shedding that may lead to spillover under specific ecological conditions.