December 26, 2013 (Silver Spring, Md.) – A vaccine containing recombinant Apical Membrane Antigen-1 (AMA1)
proteins derived from four laboratory strains of the malaria parasite Plasmodium falciparum could inhibit the
invasion of many diverse parasites collected from Africa and Asia. The results were published in the online
journal PLOS Pathogens.
“A first generation monovalent AMA1 vaccine, tested in Malian children, had earlier failed to protect broadly against malaria.
Faced with an extremely diverse parasite population, we set out to find ways to make the vaccine based on the AMA1 protein
effective against multiple parasite strains,” said, Dr. Sheetij Dutta, Ph.D., Chief of the Structural Vaccinology Laboratory
at the Malaria Vaccine Branch at the Walter Reed Army Institute of Research (WRAIR). “Antibodies against a quadrivalent AMA1
vaccine (Quadvax), surprisingly inhibited the invasion of 22 non-vaccine strains and the conserved epitopes targeted by
anti-Quadvax were mapped to two functional regions of the AMA1 molecule. These novel broadly inhibitory epitopes could
now be targeted to improve AMA1-based malaria vaccines.” said Dutta.
“Our data has wide implications for vaccine development against other diverse pathogens, such as HIV and influenza,
because polyvalent vaccines, those containing a mix of immune-system stimulating proteins from multiple strains,
are generally believed to protect by inducing a multitude of type-specific inhibitory antibodies. However, our data
showed that a vaccine containing only a small subset of carefully selected diverse allelic proteins could redirect
antibodies towards broadly inhibitory conserved epitopes.” said Dutta.
Scientists at the National Institutes of Health, The Burnet Institute and the La Trobe University (Australia)
collaborated in this joint effort and the project was supported by grants from the USAID Malaria Vaccine
Development Program, Malaria Vaccine Initiative and the U.S. Department of Defense (DoD).