Cell: Don't fight, "nothing to do with mosquitoes" these people are born to attract mosquitoes!

You can't dodge a female mosquito – she'll hunt down members of
any human species by tracking our carbon dioxide emissions, body temperature, and body odor.
But some of us are pronounced "mosquito-sucking constitutions" and get bitten more times than we deserve.

Blood type, blood sugar levels, eating garlic or bananas, being a woman, or a child are all popular theories
we know well.
However, Leslie Vosshall, head of the Rockefeller Laboratory for Neurogenetics and Behavior, said there is little reliable data
for most people.

That's why Vosshall and Maria Elena De Obaldia, a former postdoc in her lab, set out to explore the main theory that explains changes in mosquito attraction: changes in individual odors are related to
skin flora.
They recently demonstrated through a study that fatty acids emitted by the skin may produce an intoxicating perfume
that mosquitoes can't resist.
They published their findings in the journal Cell
.

Vosshall said: "There is a very, very strong connection
between having a lot of these fatty acids on the skin and being a mosquito smoker.
"

A game that no one wants to win

In the three-year study, eight participants were asked to wear nylon stockings on their forearms for 6 hours
a day.
They repeated this process
for several days.
Over the next few years, the researchers tested
all possible combinations through round-robin-style "tournaments.
" They used a dual-choice olfactory analyzer made by De Obaldia, which consisted of a plexiglass chamber divided into two tubes, each ending in a box
of socks.
They placed the Aedes aegypti mosquito — the main vector species for Zika virus, dengue, yellow fever and chikungunya — in the main chamber and watched how the insects flew along the tube to one or another nylon stockings
.

By far the most attractive target for Aedes aegypti mosquitoes was subject 33, which was four times more attractive to mosquitoes than the second most attractive study participant and a staggering 100 times
that of the least attractive subject, 19.

The samples in the trial were de-identified, so the experimenter did not know which participant wore which nylon
.
Still, they would notice that something unusual was happening in any trial involving subject 33 because insects would flock to that sample
.
De Obaldia said: "It will be obvious
within seconds of starting the trial.
As a scientist, that's something I'm very excited about
.
It's real
.
This is not nitpicking
.
This is a huge impact
.
”

The researchers divided the participants into high attractors and low attractors and then asked what distinguished them
.
They used chemical analysis techniques to identify 50 molecular compounds that were elevated
in the highly attractive participants' sebum, a kind of moisture barrier on the skin.
From there, they found that mosquito smokers produced much
higher carboxylic acids than less attractive volunteers.
These substances are found in sebum and are used by bacteria on our skin to produce our distinctive body odor
.

To confirm their findings, Voshall's team recruited another 56 people for validation studies
.
Once again, subject 33 was the most attractive and has always been
.

De Obaldia said: "Some of the study subjects have been involved for several years, and once we found out that if they are very attractive to mosquitoes, they have been acting like mosquitoes for several years
.
During this time, there may be many changes in the subjects of study or their behavior, but this is a very stable attribute
of a person.
”

Even the knockout can find us

Humans produce two main types of odors, while mosquitoes detect them with two different sets of odor receptors: Orco and IR receptors
.
To see if they could engineer mosquitoes so they couldn't recognize humans, the researchers created mutants
that were missing one or both receptors.
Orco mutants are still attractive to humans, being able to distinguish mosquito attractors from low attractors, while IR mutants have lost the distinction of attraction to humans to varying degrees, but still retain the ability to
find us.

This is not the result
scientists were hoping for.
"Our goal is to make mosquitoes lose all attraction to people, or make mosquitoes less attractive to everyone, whether it's subject 19 or subject 33," Vosshall said, because it could lead to the development
of more effective mosquito repellents.
But that's not what
we're seeing.
This is frustrating
.
”

These results complement a recent study by Vosshall and also published in the journal Cell that revealed redundancy in the sophisticated olfactory system of the Aedes aegypti mosquito
.
This is an insurance measure
that female mosquitoes rely on to survive and reproduce.
Without blood, she couldn't
do anything.
That's why "she has a fallback plan, fallback after fallback, and adjusts for differences in the chemical makeup of the skin of the people she tracks," Vosshall said
.

Mosquito odor trackers look indestructible, and it's hard to imagine a future where we're not the first meal
on the menu.
But one potential avenue is to manipulate our skin's microbiome
.
Applying sebum and skin bacteria from the skin of a person with low attraction like subject 33 to the skin of a person with high attraction like subject 19 may produce a mosquito coil effect
.

Vosshall said: "We haven't done such an experiment
yet.
It was a difficult experiment
.
But if that's effective, then you can imagine that by diet or microbiome intervention you put bacteria on the skin to somehow change their interaction with sebum, and then you can turn people like subject 33 into subject 19
.
But all this
is very speculative.
”

She and her colleagues hope the paper will inspire researchers to test other species of mosquitoes, including the Anopheles mosquitoes that transmit malaria, Vosshall added: "I think it would be very, very cool
to figure out if this is a universal effect.
"