Meeting Abstract
The role that microbes play in host-parasite interactions is currently poorly understood. In aquatic environments, the host-associated microbiome (HAM) of fish and salamander skin has been found to be highly important to their general health and ability to fend off other pathogens. Current research focuses primarily on end-infection dysbiosis, or an altered microbial state from normal thought to be caused by parasitic infection or activation of the immune system. Here, we were interested in elucidating whether the microbiome present on the host pre-infection could predict subsequent infection susceptibility to the parasite. To address this question, we used a monogenean ectoparasite, Gyrodactylus turnbulli, and its host the Trinidadian Guppy (Poecilia reticulata) to untangle the relationships between host, parasite, and the HAM. Guppies were either experimentally- or sham-infected with G. turnbulli and housed individually. The number of parasites present on each fish was counted every 48 hours, and we quantified each fish’s infection susceptibility using the area under the curve of infection load over time. We swabbed fish skin to inventory the skin HAM before infection (Day 0) and during late infection (Day 15). We identified several bacterial taxa whose relative abundance in the skin HAM prior to infection significantly predicts subsequent G. turnbulli infection susceptibility (Sphingobium, Agromyces, Methylococcaceae, and Gemmata). Our results therefore demonstrate that skin microbiome community composition significantly predicts susceptibility to an ectoparasitic helminth. Future experiments will elucidate the mechanisms underlying this effect – do bacteria and parasite interact directly, indirectly, or are they correlates of a third process?
