A potent malaria vacci ne with virtually no si de-effects has cleared
clinical trials. The new “highly protective“ malaria vaccine was successful in
humans and can pave the way for treatment of other parasitic diseases.
Scientists from the US genetically engineered the plasmodium parasite
that causes the disease, after being passed on from mosquitos, to remove three
genes that lead to infection. Although they can't multiply , they live in the
liver and stimulate the body's defences to repel a real infection.
Plasmodium parasites first infect the liver and then blood, leading to
more than 200 million infections and nearly half a million deaths worldwide in
2015. “The most clinically advanced vaccine in development contains fragments
of the malaria parasite and is only partially protective,“ said James Kublin
from University of Washington.
Vaccination with whole, live-attenuated parasites offers an alternate
approach, but its potential to cause breakthrough malaria infection poses
formidable safety challenges. To overcome these hurdles, researchers created
genetically attenuated parasites (GAP) by knocking out three genes (GAP3KO) in
plasmodium falciparum that arrested its development within the liver, thereby
preventing its advance to blood infection, the stage of malaria that triggers
disease symptoms.
The GAP3KO vaccine was administered through infected mosquito bites in a
controlled setting. The participants during the human trial, none of whom
developed malaria symptoms or signs of infection in the blood, showed strong
protective antibody responses, researchers said. When transferred into
humanised mice, these antibodies blocked malaria infection in the liver. These
promising results pave the way to phase 1b trial of GAP3KO vaccine.
Doctor Sebastian Mikolajczak, Centre for Infectious Disease Research
scientist, said, “The clinical study now shows that the GAP3KO 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.“
Source: TIMES OF INDIA-6th January,2017
