Scientists engineer dengue-resistant mosquitoes to stop them passing it on to people

There is hope in the horizon that malaria, yellow fever, dengue fever, zika virus and other mosquito-borne diseases could soon be wiped out.

Scientists have in a recent study demonstrated how mosquitoes could be genetically engineered to stop them spreading dengue fever to humans.

Working in a lab, scientists created mosquitoes, which were immune to the tropical disease and therefore unable to pass it on through bites.

They injected the insects with human immune system proteins, which were able to fight off all four strains of dengue.

These proteins stopped the virus from multiplying inside the mosquito, meaning it never became strong enough to be transmitted.

Dengue threatens the health and lives of millions of people living in hot countries every year, and can cause fever, vomiting and deadly bleeding.

Scientists at the University of California, San Diego, United States (U.S.), implanted the dengue immune proteins, called antibodies, into female mosquitoes.

Antibodies are created naturally by the body and are what enables the immune system to destroy bacteria and viruses by itself without medical help.

But someone must become infected with, or exposed to, an illness before the body is able to develop them, which is risky with such a deadly disease.

The researchers found putting human dengue antibodies into mosquitoes stopped the disease spreading among the insects.

And by engineering the genes of the insects to make sure those with the antibodies inside them were successful breeders, researchers said it would be possible to make this immunity spread through the wild population of the insects.

The research was published in the journal PLOS Pathogens.

In Nigeria, dengue fever caused by dengue virus, types 1 and 2 has been diagnosed for many years. Although, sero-epidemiological surveys have shown that dengue virus activity is, widespread in the country, there is scanty information on dengue, hemorrhagic fever with little attention paid to dengue fever largely, because it presents as classical dengue fever characterized by fever, myalgia, headache, arthralgia, retro-orbital pain, gastro intestinal, symptoms and skin rash.

According to a study titled “Dengue haemorrhagic fever: An emerging disease in Nigeria, West Africa” and published in the Journal of Infection and Public Health, dengue virus 3 and 4 have been recently detected in Nigeria, with the emergence of dengue haemorrhagic fever for the first time. Poor, surveillance, underreporting, and misdiagnosis of the disease as malaria, are major problems.

The dengue virus, for which there is no known cure, is generally mild and passes in around a week. Normal symptoms include fever, a severe headache and nausea and vomiting.

However, in rare cases the virus can become life-threatening, with symptoms including severe skin bleeding, organ failure and dangerously low blood pressure.

Around 390 million people per year globally catch dengue, with cases common in Asia, the Caribbean, and North, South or Central America.

There are also an estimated 12,500 deaths from the virus each year. The Aedes aegypti is the main mosquito that spreads dengue. It also spreads yellow fever and Zika.

Professor Omar Akbari, who led the study, said: “Once the female mosquito takes in blood, the antibody is activated and expressed – that’s the trigger.

“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.

“It is fascinating that we now can transfer genes from the human immune system to confer immunity to mosquitoes.”

The breakthrough marks the first time that all four types of the dengue virus have been targeted through engineering mosquitoes.

Previous attempts had only managed to tackle single strains.