Researchers have found a way to reduce how effectively mosquitoes can transmit dengue fever, at least in the lab—and their work could be a step toward stopping the spread of the disease, which infects about 390 million people every year and can, in rare cases, be deadly.
The dengue virus is spread by the Aedes aegypti mosquito when the insect takes a bloodmeal from an infected human host. The virus goes through several phases and eventually infects the mosquito's salivary glands, which means the next person it bites will be exposed.
A recent study in PLOS Neglected Tropical Diseases looks at genetically modified mosquitoes that were designed to be resistant to the dengue virus—and it seems that these researchers' methods worked.
An international team, based in the US, Singapore and Thailand, modified the molecular pathways inside about 400 Aedes aegypti mosquitoes to stop the spread of the virus to the insects' salivary glands.
Usually, proteins called Dome and Hop turn on a specific signaling pathway, called JAK/STAT, that fights dengue inside the mosquito after it is infected. Researchers modified the Dome and Hop proteins to activate more quickly—right after the blood was ingested—to kickstart the anti-dengue system.
When they checked the modified mosquitoes after they had ingested infected mouse blood, the set with modified Dome proteins had 78 percent less copies of the virus than what was seen in an infected mosquito outside the lab. Another set, with modified Hop proteins, had 83 percent fewer copies of the virus—so the virus was still there, but it didn't make as many viruses as it usually does to spread to the next host.
"It may be possible to achieve improved or total resistance to dengue and other viruses by expressing additional transgenes in multiple tissues that block the virus through different mechanisms," the researchers stated in a release.
About half of the world's population is at risk of infection from dengue fever, according to the World Health Organization. The virus causes flu-like symptoms at first, but serious cases can cause a high fever, bleeding from the gums and extreme muscle or bone pain. There is a vaccine.
Aedes aegypti have been causing problems for much of the Americas, since that mosquito also spreads the Zika virus, which is similar to dengue. Elsewhere, researchers are attempting to release male mosquitoes that are genetically modified to produce non-viable in the Florida Keys to mate with local females—females are the only ones that bite—to help curb the virus's spread.
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