Posted by Vector and Vector-borne Disease Committee
July 3, 2022
Cell 2022 [in press].
Zhang H., Zhu YB, Lui ZW, Peng YM, Peng WY, Tong LQ, Wang JL, Lui QY, Wang PH, Cheng G.
School of Medicine, Tsinghua University, China.
From a summary by Kate Baggaley. Popular Science. https://www.popsci.com/health/mosquito-virus-smell-sweeter/
Summary [partial]: To understand how the viruses might use odor to aid their own transmission, Cheng’s team first demonstrated that when given a choice between dengue and Zika virus infected and healthy mice, more mosquitoes [presumably Aedes] tried to feed on the infected rodents. The researchers then filtered out the chemicals … from the air around the rodents to mute the scent of their infections. Without that cue, mosquitoes downwind of the mice attempted to feed on healthy animals just as often as sick ones.
The researchers next analyzed the chemical composition of the volatiles and identified 20 compounds that increased or decreased in Infected mice. Using electroantennography, they found that acetophenone [a byproduct from Bacillus skin bacteria] prompted the strongest response. Infected mice produced 10 times more of this compound than uninfected mice. In choice assays, mosquitoes were more attracted to healthy mice or humans treated with acetophenone than those without treatment. Treating skin of infected mice with alcohol to eliminate the bacteria eliminated mosquito preference. Mammals typically produce RELMɑ proteins to counter act skin bacteria and production can be enhanced by vitamin A derivatives used to control acne. Attraction to infected mice was reduced after the mice were fed compounds derived from vitamin A.
Note: These interesting experiments were well done, but almost entirely used laboratory mice as hosts which have a different skin biota from humans. Flavivirus infections in mice normally raise body temperature and increase respiration with more CO2 emission, but these factors did not seem to influence the results of these experiments. These studies produced interesting insight into how arboviral infections may enhance transmission by increasing the frequency with which viremic hosts are fed upon and help explain how DENV and ZIKV can be transmitted efficient by low vector populations.