Detection and discovery of novel arboviruses in Western Australia

Abstract

Viruses from several recognized arthropod-borne virus families are regularly isolated in Australia. Many of these are important human and animal pathogens, and the emergence of novel or exotic arboviral pathogens pose additional threats. In Western Australia, arbovirus activity is monitored by the Arbovirus Surveillance and Research Laboratory. Viruses are isolated in cell culture from pools of mosquitoes, and their identification is then performed using a panel of monoclonal antibodies raised against medically important viruses belonging to the Alphavirus and Flavivirus genera in an enzyme immunoassay. A collection of arbovirus cultures that had evaded serological identification were further screened using molecular methods. A series of RT-PCR assays using primer sets targeting alphaviruses, flaviviruses and orbiviruses enabled identification of many of these cultures. The identity of the remaining isolates was subsequently determined using unbiased high-throughput sequencing. Novel members of the Rhabdoviridae (Oak Vale-like virus) and Reoviridae (Stretch Lagoon orbivirus) were identified. Viruses belonging to the Mapputta virus group of the Orthobunyaviridae family were also identified, as well as a single isolate of a novel reassortant virus, whose genome consists of a bunyamwera virus-like L segment and Batai virus-like M and S segments. The identification and characterisation of these viruses has informed subsequent molecular screening activities. These findings emphasise the importance of employing combinations of laboratory-based diagnostic and detection methods for comprehensive arbovirus surveillance.