Mosquito-borne viruses encompass a range of virus families and comprise a number of significant human pathogens including flaviviruses (eg. dengue viruses, Japanese encephalitis virus and West Nile virus) and alphaviruses (eg. Ross River virus and Barmah Forest virus). Virulent strains of these viruses are continually evolving and expanding their geographic range, thus it is important to employ rapid and sensitive screening assays to detect newly emerged viruses and monitor their prevalence and spread in mosquito populations.
We have developed an assay based on monoclonal antibodies to viral RNA intermediates in cells (MAVRIC), for streamlined and economical detection and discovery of viruses from mosquito populations. This assay uses two monoclonal antibodies which target the double-stranded RNA (dsRNA) intermediate produced in cells infected with positive-strand RNA and dsRNA viruses. In order to further characterise this system, we have assessed the ability of MAVRIC to detect infection with a panel of viruses in a range of cell types, across a number of platforms including immunofluorescence (IFA) and ELISA. These antibodies bind dsRNA molecules > 40 base pairs in length, in a non-sequence specific manner, and thus detect a broad spectrum of viruses in three different arbovirus families (Flaviviridae, Togaviridae and Reoviridae). This allows the detection of novel and divergent isolates which would otherwise be missed by standard screening assays based on sequence- or antigen-specific recognition.
To date, these antibodies have been instrumental in the discovery of a number of novel viruses in mosquitoes, including a new species of the Mesoniviridae family, and three new flavivirus species. The MAVRIC system is being trialled in a number of institutes across Australia to assess its potential for integration into routine arbovirus surveillance programs.