Malaria’s long history includes many attempts to defeat it. Quinine, a substance derived from the bark of the cinchona tree, has been known to be effective against malaria since the 1600s. After the role of mosquitoes in malaria transmission was understood, scientists focused on vector control. They hypothesized that that by killing the vector, they could halt the cycle of infection. Consequently, DDT and other insecticides came into view in the mid-1900s and have been topline deterrents ever since, along with bed nets and several different anti-malaria drugs. All these tactics have helped push toward the eradication of malaria. But, are there any steps left to take?
Just this month JCI Insights published a study giving light to a new genetically attenuated parasite that could give hope for malaria vaccine. In this study they report developing a genetically attenuated parasite (GAP) that stops late in the liver stage of human malaria caused by the mosquito Plasmodia falciparum. A vaccine developed with this new GAP would target the clinically silent phase of parasite infection in the liver and prevent blood stage infection. This would not only decrease mortality in especially vulnerable groups like children under the age of five, but also would serve to block the cycle of transmission.
To engineer this GAP, selected genes are deleted from the parasite’s DNA, allowing the GAPs to stop in the liver but not reach the blood stream. This “arrest” exposes the GAPs to the immune response that blocks infection. At this time only animal studies have been conducted, and translating these outcomes to humans may prove challenging, despite promising preliminary results. However, the scientists do believe that there is sufficient evidence to move the GAP vaccine candidate into early phase clinical trials.
At the same time the Lancet published findings from researchers investigating the safety and immunogenicity of Anopheles gambiae saliva vaccine. The shot is a peptide-based vaccine derived from salivary proteins tested in humans via performing randomized, placebo-controlled, double-blind, phase 1 trial enrolling 49 healthy adult participants. The idea behind the vaccine is to train the body’s immune system to recognize the saliva proteins and mount a response that would weaken or prevent an infection.
These studies showcase how research and development are at the core for the fight against malaria.