Safety, tolerability and humoral immune responses after intramuscular administration of a malaria DNA vaccine to healthy adult volunteers

DNA-based vaccines are considered to be potentially revolutionary due to th eir ease of production, low cost, long shelf life, lack of requirement for a cold chain and ability to induce good T-cell responses. Twenty healthy ad ult volunteers were enrolled in a Phase I safety and tolerability clinical study of a DNA vaccine encoding a malaria antigen. Volunteers received 3 in tramuscular injections of one of four different dosages (20, 100, 500 and 2 500 mu g) of the Plasmoditum falciparum circumsporozoite protein (PfCSP) pl asmid DNA at monthly intervals and were followed for up to twelve months. L ocal reactogenicity and systemic symptoms were few and mild. There were no severe or serious adverse events, clinically significant biochemical or hem atologic changes, or detectable anti-dsDNA antibodies. Despite induction of excellent CTL responses, intramuscular DNA vaccination via needle injectio n failed to induce detectable antigen-specific antibodies in any of the vol unteers. Published by Elsevier Science Ltd.