STUDY SUGGESTS STRATEGY FOR MALARIA VACCINEReporting in the Feb. 8 issue of Nature, Stephen Hoffman of theNaval Medical Research Institute and his colleagues have foundone possible explanation for the failed efforts to create arecombinant vaccine for malaria.
The answer could rest on the idea that what is left out is just asimportant as what's included in an effective vaccine againstthis major worldwide health problem.
Considerable effort has been devoted over the past few yearsto developing protective malarial vaccines aimed at thePlasmodium parasites. This strategy has focused on usingrecombinant peptides based on a nine-amino acid repeatingpeptide sequence found within the Plasmodium CS protein.
Because monoclonal antibodies to this repeat region of the CSprotein have been shown to protect animals from infection, theCS repeat has been the basis for creating a protective vaccineagainst malaria.
Experimental CS protein-based vaccines have not yet inducedsignificant levels of protection in monkeys or humans. Still,they inhibit the ability of malarial parasites to invade the liver,which is a key step in the development of malaria.
Hoffman and his collaborators synthesized 137 peptides basedon different portions of the CS repeat and identified onesynthetic peptide that bound specifically to the protective anti-CS monoclonal antibody.
The team found that the experimental vaccines were unable tostimulate the production of antibodies to this protectivepeptide even though these vaccines included the peptidesequence. These results indicate that the design of recombinantvaccines will be much more complex than originally thought. Itimplies that the exclusion of extraneous amino acids may benearly as important to creating an effective vaccine as theinclusion of protective sequences. -- Cynthia Robbins-Roth,Ph.D.
(c) 1997 American Health Consultants. All rights reserved.