COS 262-1 - Unraveling the role of microbiome in host-ectoparasite infectious disease dynamics

Thursday, August 18, 2022

1:30 PM – 1:45 PM EDT

Location: 514C

Presenting Author(s)

RK

Rachael Kramp, PhD Student

PhD Student
University of Pittsburgh
Pittsburgh, Pennsylvania, United States

Coauthor(s)

LC

Lindsay Colgan

Undergraduate Researcher
University of Pittsburgh, United States
JS

Jessica Stephenson, PhD

Principal Investigator
University of Pittsburgh
Pittsburgh, Pennsylvania, United States

Background/Question/Methods

Prioritizing research on the parameters that characterize infectious disease transmission is vital for optimizing interventions during outbreaks. The spread of an infectious disease in a population is dependent on the characteristics of the host (an animal capable of becoming infected), the parasite (infecting agent), and their environment. Even when experimentally controlling for the parasite and environment across systems, there is substantial variation between infected hosts in the outcomes of their infection, called ‘host heterogeneity.’ Host heterogeneity results in the majority of infected hosts transmitting to very few others, while a small subset is responsible for most new transmission events. One under-investigated driver of heterogeneity is the microbiome—the diverse community of archaea, bacteria, fungi, and viruses that live on or in an animal host. These diverse communities perform essential functions for the host like immune system education and breakdown of complex carbohydrates. Heterogeneity between infected hosts is influenced by host behavior, which determines the rate at which infected and uninfected hosts come in contact, and host competence, the ability of a host to transmit infection to a susceptible conspecific. Research has demonstrated that the microbiome can impact both host behavior and host defense against parasites, and recently the spread of pathogens.

Results/Conclusions

To understand the role of the microbiome in host heterogeneity, I experimentally manipulated the microbial communities in the rearing water of Trinidadian guppies in one of three treatment groups consisting of conventional, probiotic, and sterilized water. The conventional treatment is wastewater from adult fish from the same lineage; probiotic is the same wastewater but inoculated with Lactobacillus acidophilus after water changes, and microbial deplete is sterilized water through the autoclave. During controlled infections with Gyrodactylus turnbulli, I closely monitored parasite loads, host behavior, and transmission to naive conspecifics. My preliminary results show reduced body size under microbial deplete conditions. Once infected with G. turnbulli, the fish with the microbial deplete demonstrated a reduction in parasite load. The probiotic and conventional fish did not appear to have any statistical differences. Manipulative experiments to examine the role of the microbiome in host heterogeneity in transmission is unique in this new frontier of microbial science and will give us unique insights into the microbiome’s role in infectious disease outcomes. Knowing how the microbiome influences disease spread could bring novel venues for controlling outbreaks.