Lymphocyte Inhibition by Cell Wall Components of Batrachochytrium dendrobatidis (Bd) 2333163

Abstract Introduction The chytrid fungus, Batrachochytrium dendrobatidis (Bd), is linked to continuing global amphibian population declines. Bd causes the lethal disease chytridiomycosis when swimming zoospores attach, encyst, form a germ tube, and invade epidermal skin cells. Disruption of the host skin results in death. Although amphibians have robust immune defenses, this fungus has evolved mechanisms to evade immunity. Previous studies have revealed three small metabolites released by Bd that inhibit lymphocyte responses. We hypothesized that another molecule or molecules associated with the fungal cell wall is also inhibitory for lymphocytes. Methods To investigate the role of cell wall components, we fragmented mature zoosporangia, isolated the cell wall components lacking other soluble factors, and cultured them with proliferating frog spleen cells (Xenopus laevis) or Jurkat T cells. The cell wall fractions were boiled or treated with a mixture of carbohydrase enzymes to investigate the nature of potential inhibitory factors. Results Enriched cell wall fragments alone inhibited proliferation of both frog spleen cells and Jurkat T cells in a dose-dependent manner. Boiling of the cell wall fragments or treatment with carbohydrase enzymes reduced their capacity to inhibit lymphocyte proliferation. Conclusion These results suggest that the active inhibitory factor in the Bd cell wall is a glycosylated protein or a protein-carbohydrate complex. Ongoing studies aim to further understand the nature of the lymphocyte inhibitory factors associated with the chytrid cell wall. Support: Vanderbilt SYBBURE Searle Undergraduate Research Program and NSF IOS-2147467. Funding Source NSF IOS-2147467 Topic Categories Veterinary and Comparative Immunology (VET)