Friday December 14, 2018
Home Science & Technology Infertility g...

Infertility gene in mosquitoes to curb malaria

0
//
Republish
Reprint

London: For the first time, researchers led by the Imperial College London, have genetically modified malarial mosquitoes so that they carry a gene that disrupts egg production in female mosquitoes.

They used a technology called “gene drive” to ensure the gene for infertility is passed down at an accelerated rate to offspring, spreading the gene through a population over time and raising the possibility of reducing the spread of disease.

Within a few years, the spread could drastically reduce or eliminate local populations of the malaria, carrying mosquito species.

The mosquito species Anopheles gambiae is a major carrier of malaria parasites in sub-Saharan Africa, where 90 per cent of annual malaria deaths occur.

Malaria infects over 200 million people each year and causes more than 430,000 deaths.

“Scientists have been trying to tackle malaria for more than 100 years. If successful, this technology has the potential to substantially reduce the transmission of malaria,” said study co-author professor Andrea Crisanti.

Normally, each gene variant has 50 per cent chance of being passed down from parents to their offspring.

In the team’s experiments with Anopheles gambiae, the gene for infertility was transmitted to more than 90 per cent of both male and female mosquitoes’ offspring.

The technique uses recessive genes so that many mosquitoes will inherit only one copy of the gene.

Two copies are needed to cause infertility, meaning that mosquitoes with only one copy are carriers, and can spread the gene through a population.

This is the first time the technique has been demonstrated in Anopheles gambiae.

The team targeted three different fertility genes and tested each for their suitability for affecting a mosquito population through gene drive, demonstrating the strength and flexibility of the technique to be applied to a range of genes.

“As with any new technology, it will be at least 10 more years before gene drive malaria mosquitoes could be a working intervention,” added professor Austin Burt from Imperial’s department of life sciences.

There are roughly 3,400 different species of mosquitoes worldwide.

“While Anopheles gambiae is an important carrier of malaria, it is only one of around 800 species of mosquito in Africa, so suppressing it in certain areas should not significantly impact the local ecosystem,” noted lead author Dr Tony Nolan.

The team aims to improve the expression of their gene drive elements. Exploring target genes is also helping the researchers to learn more about basic mosquito biology.

The results were published in the journal Nature Biotechnology.(ians)

(picture credit:upload.wikimedia.org)

Click here for reuse options!
Copyright 2015 NewsGram

Next Story

An Experimental Vaccine to Treat Malaria

Scientists hope to get a better grasp on the system these vaccines employ, known as cellular immunity. Harnessing this system could help tackle hepatitis and HIV infection.

0
Vaccines
A doctor assists people looking for treatment for malaria at a health center in San Felix, Venezuela. VOA

After decades of disappointment in efforts to develop a malaria vaccine, researchers are starting to see promise in a new approach.

While most vaccines trigger the body’s defenses to produce antibodies against a disease-causing germ, the new approach recruits an entirely different branch of the immune system.

If it works, it could open up a new route to attack other diseases, including hepatitis and possibly HIV, the virus that causes AIDS.

Nearly 450,000 people die of malaria each year, according to the World Health Organization. The parasites that cause the disease are increasingly becoming drug-resistant.

One successful vaccine has been developed so far, but it prevented only about a third of cases in a clinical study.

Experts have decided that’s better than nothing. The vaccine is being piloted in Ghana, Kenya and Malawi.

Vaccine
Defensive cells killed liver cells that were infected with malaria parasites. (VOA)

New angle

Other scientists are trying a different angle of attack.

There are basically two ways to prevent germs from causing infections. “You either prevent them from getting into cells with antibodies, or you kill them inside the cells with T-cells,” said Stephen Hoffman, chief executive officer of Sanaria, a company working on one vaccine.

Most vaccines target the infection by building up antibodies. “If you need to kill them inside the cells with T-cells, we haven’t been overwhelmingly successful,” Hoffman said.

But Sanaria is one group seeing success by targeting malaria parasites inside infected liver cells, the first stop in the complex life cycle of the disease.

One key difference is how the vaccine is delivered. Hoffman’s group tried a typical route: injecting radiation-weakened parasites into patients’ skin or muscle. That didn’t work.

But it did work when injected directly into veins.

Vaccine
A public health worker takes a blood sample from a woman to be tested for malaria in Bo Rai district, Trat province, Thailand. VOA

The weakened parasites traveled to the liver, where they set off an immune reaction. Defensive cells killed liver cells that were infected with malaria parasites.

And the liver’s defenses were ready when faced with the real thing months later.

Most of that early work has been done in mice and macaques. When Hoffman and colleagues did something similar with a handful of human patients, most were protected against infection.

No waiting

Recruiting immune cells in the liver is especially effective because “we don’t need to wait until the immune system figures out that the parasite is in the liver and starts mounting an immune response, which can take days and sometimes weeks,” said Adrian Hill, director of the Jenner Institute at Oxford University.

“By then, the malaria’s gone. It only spends a week in the liver, and then it’s out in your blood causing disease.”

Vaccine
FILE – A worker of the Ministry of Public Health and Population fumigates in the street against mosquito breeding to prevent diseases such as malaria, dengue and Zika in Port-au-Prince, Haiti, Feb. 15, 2016. VOA

Hill’s group just published a study in the journal Science Translational Medicinein which immune cells in the liver were triggered by using a protein from the parasite, rather than the entire organism.

Scientists hope to get a better grasp on the system these vaccines employ, known as cellular immunity. Harnessing this system could help tackle hepatitis and HIV infection.

Also Read: Alcohol Kills More People Than AIDS, Violence Combines: WHO

Drugs can control HIV infection but can’t eliminate it from the body.

“If somebody could get cellular immunity to work really well for vaccination, that would be transformative for a whole range of diseases,” Hill said. “Not just for infectious diseases that we want to prevent, but ones that we want to treat and we can’t treat today.” (VOA)