Tests on mice

Researchers are getting closer to an effective malaria vaccine

Microscopic image of the protozoan Plasmodium falciparum, which is responsible for malaria.

(Bild: CDC/Dr. Greene; Steven Glenn, Laboratory & Consultation Division)

The malaria parasite still kills almost half a million people worldwide every year. Swiss researchers are now one step closer to developing an effective malaria vaccine. They have identified a gene that holds out the prospect of an effective and safe live vaccine.

The researchers have genetically modified the malaria parasite so that it cannot cause malaria. Such live vaccines are already being used successfully against viral infectious diseases such as measles. They are considered safe and have few side effects.

Vaccine tested on mice
In future, the weakened parasite could be used as a live vaccine, as announced by the Swiss National Science Foundation (SNSF) on Friday. It was tested on mice. A study published in the journal "PLOS One" found that it was effective in mice.

However, there is still a long way to go before a truly safe vaccine for humans is developed. "For a vaccine that is to be administered millions of times, it must be ensured that the attenuated parasite does not get through in isolated cases and cause malaria," emphasized Volker Heussler, the cell biologist from the University of Bern responsible for the project, in the press release.

Two genes of the parasite switched off
Previously approved vaccines against malaria consist of a single protein of the malaria parasite. According to the SNSF, a vaccination currently provides protection in a maximum of seventy percent of those vaccinated and only lasts for around one year without a booster.

Researchers were therefore looking for a way to produce a more effective vaccine from an attenuated malaria parasite. In a screening process, they tested 1500 different variants of the parasite, in each of which a different gene had been switched off.

Pathogen is stopped in the liver
They found a genetically modified parasite that is stopped in the liver before it enters the bloodstream and triggers fever attacks. To make the vaccine safer, they also switched off another gene that was already known to stop the parasite in the liver stage.

For these studies, they worked with the protozoan Plasmodium berghei, which is closely related to the malaria parasite Plasmodium falciparum, but infects mice instead of humans.