248 - Determining the Epidemic Potential of Ross River Virus in the Continental United States Through the Anthropophilic Disease Vector, Aedes albopictus.

Abstract: Ross River virus (RRV) is an emerging arbovirus endemic to Australia and Papua New Guinea. It is the most medically significant arbovirus in Australia, causing an average of 5000 clinical cases per year. RRV is the causative agent of Ross River fever, the symptoms of which resemble other arboviruses with fever, rash, and headaches as common symptoms, but it is unique in that a majority of cases result in arthralgia which commonly lasts for a period of several months to a year. Despite its natural reservoir hosts being marsupials, RRV has caused a number of outbreaks in urban and island areas in a total absence of marsupial hosts, presumably driven by a transmission cycle between human hosts and anthropophilic mosquito disease vectors. This could potentially indicate an evolutionary shift towards new host populations and could open the door to outbreaks well outside of RRV’s endemic range, and as such there is an imperative to determine the likelihood of outbreaks in the continental United States. To this end, we examined the vector competence of Aedes albopictus with regards to RRV by quantifying the viral titers in the bodies, legs, and heads using RT-qPCR at 2, 7, 10, 13, and 16 days post-oral infection to determine the capacity for infection and dissemination respectively. We also collected saliva daily using a filter paper collection method and tested these samples for viral RNA daily in order to demonstrate the capacity for transmission as well as estimate the extrinsic incubation period. Finally, we performed a survival assay to determine whether RRV infection would impact the mosquitos’ life expectancy, and we repeated each experiment at 20, 24.5, and 29 degrees Celsius. We used this data to construct a model to determine the vectorial capacity of RRV in Ae. albopictus as a function of temperature.