Molecular characterisation of Toll-like receptors in the black flying fox Pteropus alecto.

Bats are believed to be reservoir hosts for a number of emerging and re-emerging viruses, many of which are responsible for illness and mortality in humans, livestock and other animals. In other vertebrates, early responses to viral infection involve engagement of Toll-like receptors (TLRs), which induce changes in gene expression collectively leading to an "antiviral state". In this study we report the cloning and bioinformatic analysis of a complete set of TLRs from the black flying fox Pteropus alecto, and perform quantitative tissue expression analysis of the nucleic acid-sensing TLRs 3, 7, 8 and 9. Full-length mRNA transcripts from TLRs homologous to human TLRs 1-10 were sequenced, as well as a nearly intact TLR13 pseudogene that was spliced and polyadenylated. This prototype data can now be used to design functional studies of the bat innate immune system.