The discovery and characterisation of new mosquito-borne viruses provides valuable information on the biodiversity of vector-borne viruses and important insights into their evolution. In this study, a broad-spectrum virus screening system, based on the detection of long double-stranded RNA in inoculated cell cultures, was used to investigate the presence of novel viruses in mosquito populations of northern Australia. We detected and isolated a new virus (tentatively named Parry's Lagoon virus, PLV) from Culex annulirostris, Culex pullus, Mansonia uniformis and Aedes normanensis mosquitoes that shares genomic sequence similarities to Corriparta virus (CORV), a member of the Orbivirus genus of the family Reoviridae. Despite moderate to high (72.2% to 92.2%) amino acid identity across all proteins when compared to CORV, and demonstration of antigenic relatedness, PLV did not replicate in several vertebrate cell lines that were permissive to CORV. This striking phenotypic difference suggests that PLV has evolved to have a very restricted host range, indicative of a mosquito-only life cycle.
Keywords: Culex annulirostris; arbovirus; double-stranded RNA; insect-specific virus; mosquito; orbivirus; reovirus; virus discovery.