Portugal: Institute of Molecular Medicine-led team paves way to malaria vaccine

An international team of researchers led by Miguel Prudêncio from Portugal’s Institute of Molecular Medicine (iMM) has tested the potential of a new malaria vaccine on 24 volunteers, with results that the institution says pave the way for an effective vaccination strategy.

The team, which also includes Robert Sauerwein from Radboud University Medical Centre and Perry van Genderen from Erasmus MC (UMC Rotterdam), both in the Netherlands, on Wednesday published in the scientific journal ‘Science Translational Medicine’ results of the Phase 1/2a clinical trial of the potential new malaria vaccine, called PbVac, that involved a total of 24 healthy volunteers.

“Although none of the vaccinated subjects were fully protected against the disease, the results showed a very significant 95% reduction in liver infection in immunised versus non-immunised control subjects,” the iMM said in a news release. “This study paves the way for further developments of PbVac and similar vaccines towards the development of an effective human malaria vaccination strategy.”

The study “provides the clinical validation of a new approach to malaria vaccination, and opens possibilities for its optimisation towards the creation of an effective vaccine against malaria,” the statement quotes Miguel Prudêncio as saying.

Malaria is a disease caused by Plasmodium parasites that caused more than 400,000 deaths in 2018 alone.

The clinical development of a malaria vaccine has been a critical challenge for numerous international research groups over the years due to the complex biology of malaria parasites, whose life cycle includes several stages that occur in both the species of mosquito that is vector of the disease and the mammalian host, including a mandatory and asymptomatic stage of development in the human liver.

PbVac is the first member of a new class of “whole organism” type agents designed for malaria vaccination, consisting of a rodent malaria parasite called Plasmodium berghei, which has been genetically altered to become “masked” with a protein of its human-infecting counterpart, P. falciparum.

Prudêncio, as leader of the group at Portugal’s iMM and head for the study, is quoted as saying that the innovative idea of using rodent parasites, which are not pathogenic for humans, as the basis for a new malaria vaccine arose a decade ago.

After pre-clinical validation of the immunogenicity and safety of PbVac for human use, the researchers moved on to a clinical trial involving 24 healthy volunteers to verify the safety and protective efficacy of PbVac in the clinic.

The results showed that PbVac is safe and well tolerated, with a very significant 95% decrease in P. falciparum liver infection – the first stage of malaria infection in humans – in immunised volunteers.