Characterization of toll-like receptors 1–10 in spotted hyenas

Abstract

Previous research has shown that spotted hyenas (Crocuta crocuta) regularly survive exposure to deadly pathogens such as rabies, canine distemper virus, and anthrax, suggesting that they have robust immune defenses. Toll-like receptors (TLRs) recognize conserved molecular patterns and initiate a wide range of innate and adaptive immune responses. TLR genes are evolutionarily conserved, and assessing TLR expression in various tissues can provide insight into overall immunological organization and function. Studies of the hyena immune system have been minimal thus far due to the logistical and ethical challenges of sampling and preserving the immunological tissues of this and other long-lived, wild species. Tissue samples were opportunistically collected from captive hyenas humanely euthanized for a separate study. We developed primers to amplify partial sequences for TLRs 1-10, sequenced the amplicons, compared sequence identity to those in other mammals, and quantified TLR expression in lymph nodes, spleens, lungs, and pancreases. Results show that hyena TLR DNA and protein sequences are similar to TLRs in other mammals, and that TLRs 1-10 were expressed in all tissues tested. This information will be useful in the development of new assays to understand the interactions among the hyena immune system, pathogens, and the microbial communities that inhabit hyenas.

Markedly Elevated Antibody Responses in Wild versus Captive Spotted Hyenas Show that Environmental and Ecological Factors Are Important Modulators of Immunity

“…The feasibility and impact of comparative immunology research should be augmented by the rapidly increasing availability of published genomes and decreasing costs of monoclonal antibody production, which should allow reagents, such as isotype subclass specific antibodies, to be developed in a cost-effective manner for non-traditional study species. The recent discovery of the important role of TLR10, which is expressed in human and hyenas but not in mice [75], in the innate immune response to influenza virus in humans [76] suggests that some infectious disease research might progress more rapidly by incorporating comparative studies of non-traditional species. However, in future studies, we do caution that the genetic distance between the captive and wild populations should be minimal, and meticulous monitoring and record keeping are needed to establish unambiguous differences between the captive and wild populations.…”

Long-Read Genome Sequencing Provides Molecular Insights into Scavenging and Societal Complexity in Spotted HyenaCrocuta crocuta

“…4 D and supplementary table 17 , Supplementary Material online ). Indeed, due to their specific feeding behavior, spotted and striped hyenas are repeatedly exposed to pathogens from the carcasses they scavenge ( Flies et al 2014 ; Zhou et al 2020 ). Chronic exposure to pathogens may have resulted in adaptive changes in various pathways, including DNA damage and repair, disease resistance, and immunity.…”