Seasonality of host immunity in a tropical disease system

• Main Author: Rosa, Gonçalo M.
• Publication Date: 2022
• Other Authors: Perez, Rachel, Richards, Lora A., Richards‐Zawacki, Corinne L., Smilanich, Angela M., Reinert, Laura K., Rollins‐Smith, Louise A., Wetzel, Daniel P., Voyles, Jamie
• Format: Article
• Language: eng
• Source: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Download full: http://hdl.handle.net/10451/58092

Infectious disease systems frequently exhibit strong seasonal patterns, yet themechanisms that underpin intra-annual cycles are unclear, particularly intropical regions. We hypothesized that host immune function fluctuates sea-sonally, contributing to oscillations in infection patterns in a tropical diseasesystem. To test this hypothesis, we investigated a key host defense of amphib-ians against a lethal fungal pathogen,Batrachochytrium dendrobatidis(Bd).We integrated two field experiments in which we perturbed amphibian skinsecretions, a critical host immune mechanism, in Panamanian rocket frogs(Colostethus panamansis). We found that this immunosuppressive techniqueof reducing skin secretions in wild frog populations increasedBdprevalenceand infection intensity, indicating that this immune defense contributes toresistance toBdin wild frog populations. We also found that the chemicalcomposition and anti-Bdeffectiveness of frog skin secretions varied across sea-sons, with greater pathogen inhibition during the dry season relative to thewet season. These results suggest that the effectiveness of this host defensemechanism shifts across seasons, likely contributing to seasonal infection pat-terns in a lethal disease system. More broadly, our findings indicate that hostimmune defenses can fluctuate across seasons, even in tropical regions wheretemperatures are relatively stable, which advances our understanding of intra-annual cycles of infectious disease dynamics.