Skeeter spit is no friend to our immune system.
Every time a https://www.popsci.com/tags/mosquitoes" rel="nofollow - mosquito
bites you, she injects a bunch of goodies into your bloodstream. These
ingredients help her to slurp up a meal by stopping your https://www.popsci.com/tags/blood" rel="nofollow - blood
from clotting and keeping your blood vessels dilated. However, mosquito
spit serves a more nefarious purpose as well. Scientists http://journals.plos.org/plosntds/article?id=10.1371/journal.pntd.0006439" rel="nofollow - reported today
that mosquito saliva causes far-reaching changes in the immune system
that last for a least a week in mice after they’ve been bitten. This may
explain how saliva from mosquitoes and other pests such as ticks and
sand flies primes our bodies to be more vulnerable to diseases like
malaria and dengue fever.
It’s concerning that mosquito spit has such a strong effect on the
immune system. But there is a way we can fight back. Scientists are https://academic.oup.com/jid/advance-article/doi/10.1093/infdis/jiy179/4956143#115994201" rel="nofollow - developing vaccines that will combat mosquito saliva itself rather than a single virus, bacteria, or parasite.
“You can try to protect against many, many different pathogens in one
fell swoop, with one vaccine,” says Rebecca Rico-Hesse, a virologist at
Baylor College of Medicine in Houston and coauthor of the new paper.
“That way we could actually have some weapons against emerging viruses.”
To make such a weapon possible, we’ll need to learn more about how
our immune systems react to mosquito saliva. One strength of the new
study is that the mice in question were engrafted with human stem cells,
giving them an
https://www.popsci.com/is-it-possible-to-boost-your-immune-system" rel="nofollow - immune system
that more closely resembles our own, says Jessica Manning, an
infectious diseases physician at the National Institutes of Health’s
Malaria and Vector Research Laboratory in Phnom Penh, Cambodia. This
gives us a clue as to what a human response to mosquito saliva might
look like without having to dissect people’s bone marrow and
https://www.popsci.com/freedivers-spleens-bajau" rel="nofollow - spleens.
Every time a https://www.popsci.com/tags/mosquitoes" rel="nofollow - mosquito
bites you, she injects a bunch of goodies into your bloodstream. These
ingredients help her to slurp up a meal by stopping your https://www.popsci.com/tags/blood" rel="nofollow - blood
from clotting and keeping your blood vessels dilated. However, mosquito
spit serves a more nefarious purpose as well. Scientists http://journals.plos.org/plosntds/article?id=10.1371/journal.pntd.0006439" rel="nofollow - reported today
that mosquito saliva causes far-reaching changes in the immune system
that last for a least a week in mice after they’ve been bitten. This may
explain how saliva from mosquitoes and other pests such as ticks and
sand flies primes our bodies to be more vulnerable to diseases like
malaria and dengue fever.
It’s concerning that mosquito spit has such a strong effect on the
immune system. But there is a way we can fight back. Scientists are https://academic.oup.com/jid/advance-article/doi/10.1093/infdis/jiy179/4956143#115994201" rel="nofollow - developing vaccines that will combat mosquito saliva itself rather than a single virus, bacteria, or parasite.
“You can try to protect against many, many different pathogens in one
fell swoop, with one vaccine,” says Rebecca Rico-Hesse, a virologist at
Baylor College of Medicine in Houston and coauthor of the new paper.
“That way we could actually have some weapons against emerging viruses.”
To make such a weapon possible, we’ll need to learn more about how
our immune systems react to mosquito saliva. One strength of the new
study is that the mice in question were engrafted with human stem cells,
giving them an https://www.popsci.com/is-it-possible-to-boost-your-immune-system" rel="nofollow - immune system
that more closely resembles our own, says Jessica Manning, an
infectious diseases physician at the National Institutes of Health’s
Malaria and Vector Research Laboratory in Phnom Penh, Cambodia. This
gives us a clue as to what a human response to mosquito saliva might
look like without having to dissect people’s bone marrow and https://www.popsci.com/freedivers-spleens-bajau" rel="nofollow - spleens .
Previously, Rico-Hesse and her colleagues http://jvi.asm.org/content/86/14/7637" rel="nofollow - have seen
that this type of mouse develops more severe symptoms of dengue fever
after being bitten by mosquitoes than when the researchers injected the
virus with a needle. This happens because our bodies have an allergic
reaction to mosquito saliva (the reason we get those itchy red bumps).
“The virus present in that mosquito’s saliva, it’s like a Trojan
horse,” Manning says. “Your body is distracted by the saliva [and]
having an allergic reaction when really it should be having an antiviral
reaction and fighting against the virus.” Thus, the immune system does
not attack the virus as fiercely as it needs to. On top of this, the
saliva attracts immune cells that are susceptible to the germ. “Your
body is unwittingly helping the virus establish infection because your
immune system is sending in new waves of cells that this virus is able
to infect,” Manning says.
This time around, Rico-Hesse and her team exposed mice to mosquito
spit without any trace of dengue. They discovered that the immune
response to mosquito https://www.popsci.com/tags/saliva" rel="nofollow - saliva
lasts longer and ropes in more different types of cells than had
previously been suspected, including ones from the bone marrow. Seven
days after the mice had encountered mosquitoes, the team detected these
immune cells traveling to the site of the bite. Since immune cells also
migrate back to the marrow, it may become a reservoir for any https://www.popsci.com/tags/viruses" rel="nofollow - viruses that happen to be lurking in mosquito saliva, Rico-Hesse speculates.
“We had no idea that saliva was doing all these things to make [the
body] a better replication ground for the viruses or parasites,” she
says. “Mosquito saliva has evolved to modify our entire immune system
and it’s basically setting it up for pathogens to replicate easier and
to cause more disease.”
It’s also possible that being constantly bitten by mosquitoes could
have negative consequences for our immune systems even when the bugs
aren’t carrying any viruses.
“There must be other effects that we haven’t even begun to measure,” says Rico-Hesse, who published the findings in the journal PLOS Neglected Tropical Diseases. “It opens up a whole can of worms in terms of what people are being exposed to when we’re being bitten by mosquitoes.”
Vaccines to stymie spit
So the sooner we can make a vaccine against mosquito spit, the
better. As a first step, both Rico-Hesse and Manning are trying to
figure out which proteins in mosquito saliva are responsible for helping
pathogens infect us more easily. Other scientists are doing the same
for https://www.tandfonline.com/doi/full/10.1586/14760584.2016.1105135" rel="nofollow - sand fly and https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5459892/" rel="nofollow - tick spit .
Their hope is to prevent bug saliva from messing with our immune
system so our bodies will attack any germs carried along with it more
effectively. “Perhaps your body is going to maintain that fighting
stance... as opposed to launching into an allergic response,” Manning
says.
Scientists would also add ingredients to the vaccine that would
encourage the body to mount an even more intense response to destroy the
pathogen. This strategy is used in many of today’s vaccines, including
those for tetanus, hepatitis, and https://www.popsci.com/science/article/2013-07/attn-men-hpv-vaccine-works-against-oral-infections-too" rel="nofollow - human papillomavirus , Manning says.
She and her colleagues have also been working with SEEK, a
pharmaceutical company in the United Kingdom, to develop a vaccine
against a handful proteins in spit from a mosquito that transmits
malaria, Anopheles gambiae. They have https://www.nih.gov/news-events/news-releases/nih-begins-study-vaccine-protect-against-mosquito-borne-diseases" rel="nofollow - begun testing the vaccine in people, and hope that it may be effective against spit from other kinds of mosquitoes as well.
“It would be a feat if there was a universal vaccine—one single
vaccine for all mosquito-borne disease,” Manning says. However, creating
a vaccine against one type of mosquito saliva is a more realistic goal
for the next decade, she says.
Meanwhile, Rico-Hesse is focusing on spit from Aedes aeygpti, the mosquitoes that transmit https://www.popsci.com/tags/dengue" rel="nofollow - dengue and a host of other ailments. “If we can get something to work against the Aedes aeygpti
salivary proteins, not only could we be impacting the transmission of
dengue but Zika, yellow fever, [and] all the other viruses,” she says.
One potential problem with saliva-based vaccines is that they may
wear off quickly. There’s some evidence that people may be slightly less
likely to get infected with https://www.popsci.com/tags/malaria" rel="nofollow - malaria if they are constantly bitten by Anopheles
mosquitoes. However, when these people leave town for a few months, the
antibodies they have made against the mosquito spit disappear. So the
immunity bestowed by a spit vaccine may not last very long on its own.
On the other hand, for people who live in areas swarming with these
mosquitoes, being bitten all the time may act as a kind of booster shot.
Ideally, we’d receive spit https://www.popsci.com/tags/vaccines" rel="nofollow - vaccines
along with those designed to target particular diseases. But vaccines
against mosquito saliva would come especially in handy to fight emerging
viruses that we haven’t developed vaccines for yet. Typically, we can’t
create new vaccines fast enough to halt an https://www.popsci.com/tags/epidemics" rel="nofollow - epidemic , Manning says. Scientists developed https://www.popsci.com/tags/zika" rel="nofollow - Zika
vaccines at breakneck speed, but they still were not ready by the time
the recent epidemic had waned. If we had saliva vaccines on hand, it
could potentially help stem future epidemics, Manning says.
Rico-Hesse expects it will take at least 10 years to figure out which
mosquito saliva proteins have the biggest impact on our immune system
and see if immunizing against them does in fact prevent disease
transmission. “We’re just at the beginning of understanding how saliva
works in mosquito-borne diseases,” she says.
Still, mosquitoes kill about 1,700 people a day around the world,
Manning says. And, as the Centers for Disease Control and Prevention
https://www.cdc.gov/vitalsigns/vector-borne/index.html" rel="nofollow - recently reported ,
the number of cases of mosquito-borne diseases has only been rising in
recent years in the United States. “Any dent that we can make in those
numbers would be meaningful,” Manning says.
Source:
https://www.popsci.com/mosquito-spit-disease-vaccine#page-3" rel="nofollow - https://www.popsci.com/mosquito-spit-disease-vaccine#page-3