RESEARCHERS have developed a rapid screening tool to detect and monitor mosquito-borne viruses, eliminating the need for lengthy and laborious virus detection methods.

Mosquito-borne viruses can be transmitted to humans through mosquito bites / Image courtesy - Wikimedia Commons

The limitations of standard surveillance systems for detecting mosquito-borne viruses inspired a collaborative effort from a University of WA researcher, Associate Professor Cheryl Johansen, and colleagues in WA and Queensland to develop and test a new method for virus monitoring. 

This tool, which is capable of detecting a range of mosquito-borne viruses including Ross River, Barmah Forest, Kunjin, chikungunya and Murray Valley encephalitis, relies on the action of mosquitoes expelling virus-containing saliva onto honey-soaked cards held within a trap.

“We confirmed that the mosquitoes actually deposited saliva with virus when they fed on the honey,” says Assoc. Prof Johansen from UWA’s School of Biomedical, Biomolecular and Chemical Sciences.
 
“Mosquitoes are held in a trap with four or six of these cards that have the honey soaked into them and by feeding on the cards, the mosquitoes are depositing the virus.

“The virus actually dies because the card denatures the all the proteins but you are still able to detect the virus genome (RNA) on the card.”

The cards are collected, processed and analysed for virus by polymerase chain reaction-based methods. According to Assoc. Prof Johansen, one of the advantages of this trap is that it can be attended to once a week and would therefore be beneficial in remote areas.

“Also, if you’re detecting the virus genome on these cards, the mosquitoes have to have deposited virus on there in the saliva so it means that the mosquito was physically capable of transmitting the virus (vector-competent).

“As opposed to if we collect mosquitoes in traps, we test the whole mosquito to see if they’ve got viruses in them by virus isolation. 

“You don’t necessarily know that the mosquito that had the virus in it was vector-competent whereas with this card system, the mosquito must have been because it transmitted the virus.”

The tool, which is undergoing modifications to potentially eliminate the need for a power-supply, is being tested alongside standard systems for the surveillance of mosquito-borne viruses.

“We ran a trial of this trapping system in parallel with the sentinel chickens in Kununurra,” says Assoc. Prof Johansen.

“We have flocks of sentinel chickens around the state and volunteers to take blood samples from them every fortnight.  The samples then get sent down to us and we test them and if they [the chickens] have developed antibodies, we know that those viruses have been active.”

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