Detection of mammalian antibodies against Ross River virus in mosquito blood meals and potential for arbovirus surveillance

Mosquito-borne alphaviruses are the causative agents of several debilitating diseases that have been associated with large, cross continental outbreaks, as demonstrated recently by chikungunya virus. Ross River virus (RRV) is an alphavirus endemic to Australia and the Pacific which is the agent of a debilitating disease with symptoms including fever, arthritic joint pain and rash. RRV is characterized by a broad association with a variety of mosquito vectors and vertebrate hosts. A number of these hosts are native Australian marsupials, including kangaroos, wallabies and koalas. The complex ecology of the virus present large challenges for disease surveillance, epidemiology and control. We are developing a novel xenodiagnostic assay strategy to determine the seroprevalence of RRV antibodies among vertebrate host populations. The strategy avoids animal ethics dilemmas by harnessing the natural behavior of resident mosquito populations to sample blood from a wide variety of vertebrate hosts. We demonstrate the ability to detect RRV IgG from within mosquitoes that originate from any vertebrate host species. We are utilizing a population of koalas with a seroprevalence for RRV IgG of 75% and a colony of flying foxes (Pteropus spp.) in a suburb of Brisbane. This work will provide insights and strategies for improved epidemiology of RRV and potentially other mosquito-borne diseases.