This is a past event.

Dr. Clara Shaw, Disease Ecologist

University of Minnesota, Duluth

Abstract:

Countless genetic and environmental factors impact susceptibility to infectious disease and the outcome of infection. We use a Caenorhabditis nematode – Orsay virus system to understand these factors through laboratory experiments. During the first part of my talk, I will discuss our work exploring the effect of maternal age on Orsay virus susceptibility and viral amplification. We found that early offspring (from young parents) had greater viral loads than later offspring (from older parents). Interestingly, when the virus was allowed to transmit in populations derived from early or late offspring, there was more viral amplification in the populations derived from the later offspring. We are now working to mechanistically understand these effects, which, at first glance, seem contradictory. During the second part of my talk, I will discuss our experiments to understand factors that govern the success of viruses following spillover of Orsay virus to Caenorhabditis species that do not naturally host the virus. Often, spillover results in dead-end infections, sometimes, in stuttering transmission chains that die out, and rarely, large epidemics and virus persistence. We exposed populations of non-natural host species to the virus and measured epidemiological characteristics of the resulting spillover process (i.e. prevalence of infection, intensity of infection, and the degree of virus shedding from novel hosts). We then quantified viral persistence in populations through a passage experiment: we used quantitative PCR to track virus persistence in passaged host populations for 10 passages or until virus was undetectable, indicating its loss. We found that sustained transmission was associated with infection prevalence in the exposed population and the ability of exposed hosts to detectably shed the virus, but not with the infection intensity. Though there are few other experimental studies of disease emergence for comparison, our findings are in line with theory and with findings in invasion ecology: the probability of persistence increases with more introductions and pre-adaptation to the novel environment. These findings suggest that continued monitoring of pathogens known to replicate and disseminate from human cells and of spillover events that infect multiple individuals is important for disease emergence monitoring.