Texas A&M scientists solve the mystery of how mosquitoes become virulent virus hosts

When viruses invade a mosquito's body, there's a battle between the insect's immune system and the infection.

Scientists have long puzzled over what causes the virus to win that tug of war, which ultimately makes the mosquito a carrier for diseases like Zika, yellow fever, dengue and West Nile.

A team of scientists from Texas A&M University this week announced they have solved that mystery, publishing new research that shows that several mosquito-borne viruses create a protein that suppresses the insect's immune system.

The research, published in the Proceedings of the National Academy of Sciences, could lead to new advances in the fight against Zika, possibly even the development of a vaccine, the scientists say.

"It is definitely something we're looking at," said Kevin Myles, an A&M entomologist and one of authors of the research paper.

Before Myles and his colleagues Zach Adelman and Glady "Hazitha" Samuel could think about whether humans create an immune system-attacking protein when infected with a mosquito-borne virus, they had to understand the biological changes that occur in mosquitoes when they become infected.

The team's research focused on the virus that causes yellow fever, though they say the discovery applies to other viruses transmitted by mosquitoes.

In the Aedes aegypti mosquito, they found that the yellow fever virus encodes a protein that blocks the insect's immune system. In doing so, the pathogen stays one step ahead of its host, and the mosquito becomes a carrier.

"While the mosquito doesn't want the virus in its body any more than we want it in ours, and is trying to get rid of it, the virus isn't defenseless," Myles said. "It's fighting back and deploying its own countermeasures. Basically, this is what's known as an evolutionary arms race. The survival of this group of viruses depends on their ability to stay one step ahead of the mosquito's immune response."

Now that the scientists know about the protein, they might be able to trigger a response within the mosquito that could stop the virus.

By using gene drive, a method targeting specific genes, they could go in and tip the scale in the mosquito's favor. Alternatively, they could give the nod to the virus. In the latter, the virus would actually make the mosquito sick, preventing transmission to humans.

"It will also be interesting to see if this protein interferes with the human immune response," Myles said. "Certainly similar types of proteins have been found in other viruses that are not transmitted by mosquitoes but do infect people, influenza viruses for example."

Texas A&M hired Myles and Adelman away from Virginia Tech this summer to boost the university's scientific efforts to help stop the spread of Zika, a devastating virus that poses a severe threat to unborn babies.

The scientists are long-time collaborators: Myles is focused on understanding the basic biology of how certain viruses replicate in mosquitoes, while Adelman's projects involve creating mosquitoes that are resistant to viruses such as Zika.

They have their work cut out for them.

Just this week, new research was published that the Zika virus can live for several hours on non-porous surfaces, such as countertops and doorknobs, while scientists from Colorado State University announced they had discovered that some mosquitoes carrying the Zika and Chikungunya viruses are capable of transmitting both in a single bite.

From: http://www.chron.com/local/planet-texas/article/Texas-A-M-scientists-solve-the-mystery-of-how-10618027.php