The dengue virus is transmitted by mosquitoes. It is found in over one hundred countries and threatens three billion people with a serious illness that causes flu-like symptoms and rashes in one of four people that are infected, according to the Centers for Disease Control and Prevention. There is currently no treatment for the virus, which can also cause a life-threatening form of the disease called severe dengue in about five percent of infected people.
Researchers have now engineered Aedes aegypti mosquitoes that stop the virus from being transmitted. The scientists, in the lab of UC San Diego Associate Professor Omar Akbari and at Vanderbilt University Medical Center, developed the strategy; it uses an antibody carried by female A. aegypti mosquitoes that can target all four types of dengue. The study has been reported in PLOS Pathogens.
"Once the female mosquito takes in blood, the antibody is activated and expressed -- that's the trigger," explained Akbari. "The antibody is able to hinder the replication of the virus and prevent its dissemination throughout the mosquito, which then prevents its transmission to humans. It's a powerful approach."
Akbari said a gene drive based on the CRISPR gene editor could be used to spread the antibody to mosquito populations in the wild that transmit disease.
"It is fascinating that we now can transfer genes from the human immune system to confer immunity to mosquitoes. This work opens up a whole new field of biotechnology possibilities to interrupt mosquito-borne diseases of man," said study co-author James Crowe, Jr., M.D., director of the Vanderbilt Vaccine Center at Vanderbilt University Medical Center in Nashville.
"This development means that in the foreseeable future there may be viable genetic approaches to controlling dengue virus in the field, which could limit human suffering and mortality," said Akbari.
"Mosquitoes have been given the bad rap of being the deadliest killers on the planet because they are the messengers that transmit diseases like malaria, dengue, chikungunya, Zika and yellow fever that collectively put 6.5 billion people at risk globally," said Suresh Subramani, professor emeritus of molecular biology at UC San Diego and global director of the Tata Institute for Genetics and Society (TIGS). "Until recently, the world has focused on shooting this messenger. Work from the Akbari lab and at TIGS is aimed at disarming the mosquito instead by preventing it from transmitting diseases, without killing the messenger. This paper shows that it is possible to immunize mosquitoes and prevent their ability to transmit dengue virus, and potentially other mosquito-borne pathogens."
Sources: Science Daily via University of California San Diego, PLOS Pathogens
