Clinical assessment of a recombinant simian adenovirus ChAd63: a potent new vaccine vector.

ABSTRACT: BACKGROUND:Vaccine development in human Plasmodium falciparum malaria has been hampered by the exceptionally high levels of CD8(+) T cells required for efficacy. Use of potently immunogenic human adenoviruses as vaccine vectors could overcome this problem, but these are limited by preexisting immunity to human adenoviruses. METHODS:From 2007 to 2010, we undertook a phase I dose and route finding study of a new malaria vaccine, a replication-incompetent chimpanzee adenovirus 63 (ChAd63) encoding the preerythrocytic insert multiple epitope thrombospondin-related adhesion protein (ME-TRAP; n?=?54 vaccinees) administered alone (n?=?28) or with a modified vaccinia virus Ankara (MVA) ME-TRAP booster immunization 8 weeks later (n?=?26). We observed an excellent safety profile. High levels of TRAP antigen-specific CD8(+) and CD4(+) T cells, as detected by interferon ? enzyme-linked immunospot assay and flow cytometry, were induced by intramuscular ChAd63 ME-TRAP immunization at doses of 5?×?10(10) viral particles and above. Subsequent administration of MVA ME-TRAP boosted responses to exceptionally high levels, and responses were maintained for up to 30 months postvaccination. CONCLUSIONS:The ChAd63 chimpanzee adenovirus vector appears safe and highly immunogenic, providing a viable alternative to human adenoviruses as vaccine vectors for human use. CLINICAL TRIALS REGISTRATION:NCT00890019.

SUBMITTER: O'Hara GA 

PROVIDER: S-EPMC3274376 | biostudies-literature | 2012 Mar

REPOSITORIES: biostudies-literature