Meeting Abstract
Most invertebrates must rely solely on their innate immune system to defend against pathogenic microbes. Unlike the immunoglobulins of vertebrate adaptive immunity, innate immune receptors do not recombine to diversify their ligand specificity – thus it is the plurality of these receptors encoded in the genome which provide breadth of protection. In this study, we investigate the diversity of Toll-like receptor (TLR) and Interleukin-1 receptor (IL-1R) pathway genes in hemichordates. Hemichordates, alongside echinoderms, belong to the Ambulacraria – sister group to the chordates. While research has shown echinoid echinoderms exhibit a vast diversification of TLRs, the hemichordate TLR repertoire has been largely uninvestigated. Using available TLR/IL-1R pathway genes from the SwissProt database, hemichordate TLR homologues were determined through reciprocal BLAST searches cross-referenced with their associated Pfam-domain predictions (via HMMER). Our results suggest both colonial and solitary hemichordates do not possess the diversification of TLR genes observed in the echinoids. Furthermore, hemichordates may possess the genetic machinery necessary for MYD88-dependent and MYD88-independent signal transduction of the TLR/IL-1R pathway. These data provide a strong foundation for future experiments in hemichordate and ancestral deuterostome innate immunity.
