Scientists working on a malaria vaccine have reported that the vaccine has passed a critical milestone in human life safety trials. The solution employed a genetically modified form of parasites which was unable to cause a full infection in people.
The results of this research were published, Jan. 4, in the journal Science Translational Medicine, and have been described as "promising" by tropical disease experts.
One Step Closer To Malaria Vaccine
As part of the human trials, none of the 10 volunteer subjects developed the disease, and the treatment administered to them had no severe side-effects. The parasite undergoes various stages in people as well as mosquitoes. Starting from this premise, the team of scientists deleted three genes, which made the liver infection impossible to complete.
The results of this research are all the more promising, as there are roughly 5,000 malaria genes, and through the deletion of three of them, formidable results were achieved.
The mechanism behind this strategy is that people are infected with the weakened parasite, exposing their immune system. Since the lifecycle of the parasite cannot be completed, the disease will not install in the human body.
Further, the antibodies of the patients were administered to mice, which responded to the deliberated infection with a higher overall immunity.
"The clinical study now shows that the vaccine is completely attenuated in humans and also shows that even after only a single administration, it elicits a robust immune response against the malaria parasite," noted Dr Sebastian Mikolajczak, researcher of the study.
So far, two main directions have been developed in response to this threat. The first one consists of weakening the parasite itself by exposing it to radiation, while the second one, applied as part of the current research, involves strengthening the patient. The latter is a combination of administering the anti-malarial drugs to the patients and infecting them with the weakened parasites at the same time, which creates a positive response from the immune system.
"Immunization of humans with whole sporozoites confers complete, sterilizing immunity against malaria infection. However, achieving consistent safety while maintaining immunogenicity of whole parasite vaccines remains a formidable challenge," mentions the study.
Malaria, An Ongoing Threat
A completely feasible vaccine is, however, far from being developed. While there are a high number of trials under tests, the disease still affects approximately 200 million people by the year, as research points out. The disease appears as a result of plasmodium, a microscopic parasite that infects the human body through the means of mosquito bites, which allow a version of the parasite to get under the human skin.
Once in the human body, the parasite attacks the liver, where its sporozoites infect the organ with 30,000 copies of the parasite. From the liver, the parasite gets into the blood stream, where it attacks red blood cells, which sometimes results into the patient's death.
Because the infection follows these three stages, it is all the more complicated to create a fully functional vaccine to prevent it from spreading throughout the body and, finally, affecting the blood cells.