Mosquitoes are the world’s deadliest insects, responsible for transmitting pathogens that cause millions of deaths each year. Yet in regional Australia and neighbouring tropical countries, the full genetic diversity of circulating mosquito-borne viruses is not well understood. Researchers at the Australian Institute of Tropical Health and Medicine (AITHM) are working to uncover which viruses are present — and what risk they pose to humans and animals.
The AITHM’s Dr Subir Sarker and PhD candidate Md. Eram Hosen are studying mosquito populations in Far North Queensland, Papua New Guinea (PNG) and Bangladesh to identify both known and potentially novel viruses that may be quietly circulating.
“While dengue and other flaviviruses are known to occur in Queensland, for example, there is still much to learn about the diversity of viral strains and variants circulating in mosquito populations from underserved regions,” Dr Sarker said.
Currently, Queensland Health records polymerase chain reaction (PCR) test results and the number of people admitted into hospital for a certain disease. PCR tests can detect that a virus is present, but they do not provide information about the virus variant. “By complementing existing public health surveillance with advanced molecular approaches, we aim to build a more complete picture of the viruses present in tropical regions”, Mr Hosen said.
Mr Hosen has begun collecting mosquitoes across Townsville, in collaboration with Townsville City Council, as well as in PNG and Bangladesh. His research focuses on the common banded mosquito (Culex annulirostris) and the northern salt marsh mosquito (Aedes vigilax), among others. “I aim to collect around 1,000 mosquitoes for the analysis,” he said. To simplify the analysis process, Mr Hosen said he will divide the mosquitos into 50 samples consisting of at least 20-30 mosquitoes each.
“Using next-generation sequencing is the central focus of my work, and I’m planning to use both metagenomic and metatranscriptomic sequencing to identify the known and novel viruses and determine which are actively replicating,” Mr Hosen said.
“Metagenomic sequencing will identify all viral genetic material, providing insights into viral diversity and genome composition, while metatranscriptomic sequencing will reveal actively replicating RNA viruses and their expression profiles.”
Once the researchers know which novel viruses and new variants of known viruses are present in North Queensland, PNG, and Bangladesh they can apply the most effective approach for surveillance as a second step. “This research will help us improve surveillance and early warning systems,” Mr Hosen said. “If new or emerging viruses are circulating, we want to detect them early so that public health teams can take informed action.”