To do this, scientists needed to change the skin microbiome
Are you tired of buzzing and stinging bloodsuckers and repellent sprays with a pungent odor and short action? Then an innovation from scientists at the University of California and Stanford University may seem like a solution to your problem. They modified the bacteria that inhabit the skin so that they did not produce scents that were attractive to mosquitoes. The covers inhabited by the new community became “tasteless” for mosquitoes for 7-11 days!
Mosquitoes search for prey by volatile substances released by breathing and some skin bacteria. Among the many bacteria that inhabit our surfaces, scientists are interested in Staphylococcus epidermidis (skin staphylococcus) and Corynebacterium amycolat (corynebacterium — relatives of diphtheria), which are components of the natural flora and emit odors that are tasty for insects.
Microbes attract mosquitoes by producing lactic acid against the background of our good metabolism and physical activity. Scientists set out to reduce the production of this alluring component by changing the genetic makeup of staphylococcus and root bacteria. They genetically modified them and colonized the skin of laboratory mice with their strains.
The engraftment of the engineered bacteria on the skin of rodents was carried out in two stages. First, with sticky strips reminiscent of wax strips for depilation, they exposed the skin of the mice on the stomach and sides, also clearing it of the previous, natural microbiome. Then a genetically modified microbiome with reduced lactic acid production was applied to clean skin.
Unlike the most effective repellents, which act for 4 hours when applied to the skin, the new “remedy” repelled, or rather did not attract, mosquitoes for 7 to 11 (!) days.
The experimenters specify that they were able to achieve this result by depriving the bacteria of just one secreted component – lactic acid, although the skin emits many others.
The new GMO protection was tested on three species of mosquitoes: Aedes aegypti (carrier of yellow fever, Zika virus, dengue virus), Culex quinquefasciatus (southern house mosquito, carrier of West Nile virus) and Anopheles gambiae — African mosquito, carrier of tropical malaria. Females of all three species were almost indifferent to mice with an altered skin microbiome for more than a week. After this time, the microbiome of the deep layers of the skin, which is considered quite stable, repopulated the skin with the usual composition of its inhabitants-microorganisms.
Experts do not exclude that in the future, with the development of technology, a similar method could be applied to humans.
In 2022, there were about 250 million cases of malaria in humans and 400 million cases of dengue fever worldwide. Together, the diseases cause tens of thousands of deaths worldwide every year.
– This is all great, but I think that this GMO microbiome is unlikely to work on our mosquitoes. The fact is that each region has its own conditions for its existence, and, accordingly, the bacteria themselves differ. Of course, there are some basic, unchanging components of their genome, but, nevertheless, they need to be studied in their natural environment. Apart from the fact that the application of this method may be limited, the idea itself of replacing the natural microbiome with an artificial one is not bad, but, of course, requires further development.
– The thing is that we already went through something similar during the Covid times, when everyone was forced to vigorously wipe their hands with alcohol. We essentially washed away our native protective layer, becoming defenseless against the same viruses. This can also be a double-edged sword, because the same staphylococci that live on the skin participate in natural defense, and no one knows how they will behave if they become mutants.