Adenovirus Vaccine for Malaria

Malaria currently represents one of the most prevalent infections in tropical and subtropical areas throughout the world. Each year, malaria affects around 300 million people and kills 1 to 3 million people in developing countries. The widespread occurrence and the growing incidence of malaria are a consequence of the increasing numbers of drug-resistant parasites and insecticide-resistant parasite vectors. Other factors include environmental and climatic changes, civil disturbances and increased mobility of populations. It is hypothesized that the Ad35.CS.01 vaccine will prevent the Plasmodium (P.) falciparum parasite, which causes malaria, from entering and developing within the liver of those who become infected. Ad35.CS.01 would therefore be expected to reduce malaria-attributable morbidity and mortality. The purpose of this phase I, randomized, controlled, dosage-escalation trial is to evaluate the immunogenicity, safety, and reactogenicity of an Adenovirus Type 35 based circumsporozoite malaria vaccine in 72 healthy adults, 18 to 45 years of age, in the United States. Subjects will be randomized in a 5:1 ratio to receive 3 doses of the Adenovirus Type 35 circumsporozoite malaria vaccine (Ad35.CS.01) or normal saline placebo control by the intramuscular route at 0, 1 and 6 months. The safety, reactogenicity, and immunogenicity of ascending dosages of the vaccine will be assessed. Fifteen subjects will receive vaccine at each of the following dosage levels: 10\^8 viral particles (vp)/milliliters (ml), 10\^9 vp/ml, 10\^10 vp/ml and 10\^11 vp/ml with 3 subjects receiving control at each of these dosage levels. Dosage escalation will proceed only after review of the safety data by the Safety Monitoring Committee of the prior dosage level. The primary objective is to assess the safety and reactogenicity of ascending dosages of Adenovirus Type 35 based circumsporozoite malaria vaccine among healthy subjects given in 3 intramuscular doses at 0, 1 and 6 months. The secondary objective is to evaluate the immunogenicity of the Adenovirus Type 35 based circumsporozoite malaria vaccine through performance of Humoral Immune Assays \[ELISA (enzyme-linked immunosorbent assay)\] for antibodies to circumsporozoite antigen and Adenovirus Neutralization Assay for neutralizing antibodies to Adenovirus type 35) and Cellular Immune Assays \[enzyme-linked immunosorbent spot (ELISPOT) and Flow Cytometry\] for circumsporozoite (CS)-specific cluster of differentiation (CD)4+ and CD8+ T cell responses.