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Science

German scientists discover 'needle-free' malaria vaccine

By combining antibiotics and malaria-infected mosquitos, researchers find that mice are protected. Human clinical trials will be just around the corner.

Mosquito

Approximately half of all humans live in areas of the world threatened by malaria

Deep in a lab, in carefully sealed incubators, mosquitos, which normally are malaria carriers, may this time actually be part of the solution.

Kai Matuschewski and his research team from the Max Planck Institute for Infection Biology in Berlin used mosquitoes to infect test mice with malaria. At the same time, they gave the mice antibiotics for three days and the mice showed no signs of the disease.

Matuschewski says this means that he and his research team may have discovered the first so-called "needle-free" malaria vaccine. Their research was published last month in the journal Science Translational Medicine.

If successful, the vaccine would use a combination of drugs and the mosquito itself to prevent the onset of malaria. It could be a boon to billions of people worldwide who are at risk for the disease, which mainly affects people living in temperate climates.

Matuschewski said the idea behind their research was to "combine a classical prophylaxis aspect - which is antibiotic treatment - (that travelers use to protect themselves against malaria), together with a natural exposure."

"The mosquito is our sort of syringe that delivers the pathogen and we stop the parasite from growing in the liver through antibiotic prophylaxis," he said.

malaria drug

Malarone is a common anti-malarial drug

'The mice don't get sick'

While feeding, a malaria-carrying mosquito injects something called a sporozoite, which is the cell form that infects the new host.

In this case, that would be the mouse. In the real world, it could be a human. The sporozoites migrate to the liver, where they replicate massively and mature to the disease-causing blood stage cells called merozoites.

In this new German study, the merozoites continued to develop in the liver cells, but the antibiotics prevented them from infecting the red blood cells, which meant that the mice didn't get malaria symptoms.

With this treatment the mice not only didn't get sick, but they also developed long-term immunity.

The mice were infected with sporozoites again after 40 days, four months, and six months, this time without adding antibiotics, and all the animals had complete protection against malaria.

Antibiotic resistance

The antibiotics the scientists used were clindamycin and azithromycin, that are both generic, cheap and readily available. This is good news for poorer countries, but Dr. Michael Knappik, from the Berlin Center for Tropical and Travel Medicine, pointed out that there are drawbacks with using antibiotics in the long term.

"We have growing resistance against the malaria drugs we use at the moment," he said, "and that's a big problem especially in Southeast Asia, and this of course can also arise in these new antibiotic treatments."

Matuschewski and his team hope to reduce the likelihood of antibiotic resistance by administering the drugs once a year - at the onset of the rainy season. He added that antibiotic resistance isn't as pronounced in Africa as it is in Western countries, so the benefits could outweigh the concerns.

electron micrograph of a mosquito

This electron micrograph shows a female Anopheles stephensi mosquito, which often is a carrier of malaria

Clinical trials to begin next year

If successful, this new treatment could dramatically lower the one million deaths worldwide from malaria every year.

Around 600 Germans contract the disease each year, and Sebastian Hofmann was one of the unlucky ones. Seven years ago at age 19, Hofmann went backpacking across West Africa, and, despite the usual malaria prevention measures - including medicine, insect repellent and mosquito nets - he still contracted the disease.

"I was hallucinating. I was sweaty," he remembered, "I thought I was somehow in the state of being really drunk and having a really bad flu."

Hofmann contracted the worst strain of malaria and fell into a coma for three days, although he eventually recovered. While this new treatment isn't targeted at travelers in general - because you need to be infected with malaria first for it to work - it could make a big difference for people living in severely affected regions.

"In endemic areas in Kenya, in East Africa, people live there for 20 years, get infected probably sometimes 100 times a year and they always develop parasites," Matuschewski said. "So to achieve something like anti-parasitic sterile immunity is almost impossible. So what we want is to protect against disease."

Put another way, even if children living in malaria regions are protected daily with bed nets, according to Matuschewski all this does is delay their potential exposure to the disease and subsequent symptoms and complications.

So rather than trying to prevent all mosquito bites - which is virtually impossible - this new treatment uses the infection as a part of the solution in combination with the antibiotic.

Because the antibiotics are readily available, Matuschewski and his research team hope that clinical trials could start in sub-Saharan Africa, as early as the beginning of summer next year.

While they're excited about their findings, scientists like Dr Johannes Friesen from the Max Planck Institute for Infection Biology in Berlin, were careful to point out that their research is just "one component to fight the disease."

Author: Cinnamon Nippard
Editor: Cyrus Farivar

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