Within-host mechanisms of immune regulation explain the contrasting dynamics of two helminth species in both single and dual infections

by Chiara Vanalli, Lorenzo Mari, Lorenzo Righetto, Renato Casagrandi, Marino Gatto, Isabella M. Cattadori Variation in the intensity and duration of infections is often driven by variation in the network and strength of host immune responses. While many of the immune mechanisms and components are known for parasitic helminths, how these relationships change from single to multiple infections and impac t helminth dynamics remains largely unclear. Here, we used laboratory data from a rabbit-helminth system and developed a within-host model of infection to investigate different scenarios of immune regulation in rabbits infected with one or two helminth species. Model selection suggests that the immu nological pathways activated againstTrichostrongylus retortaeformis andGraphidium strigosum are similar. However, differences in the strength of these immune signals lead to the contrasting dynamics of infections, where the first parasite is rapidly cleared and the latter persists with high intensities. In addition to the reactions identified in single infections, rabbits with both helminths also activate new pathways that asymmetrically affect the dynamics of the two species. These new signals alter the intensities but not the general trend of the infections. The type of interactions described can be expected in many other host-helminth systems. Our immune framework is flexible enough to capture different mechanisms and their complexity, and provides essential insights to the under...
Source: PLoS Computational Biology - Category: Biology Authors: Source Type: research