Adenoviruses as gene/vaccine delivery vectors: promises and pitfalls.

INTRODUCTION: Adenoviruses (Ads) have attracted researchers from across the disciplines for several reasons. Their ability to recombine with and express the heterologous genes encouraged their development as gene/vaccine delivery vectors. Preclinical and clinical trials using these vectors have shown significant promise for their future development while highlighting certain limitations. AREAS COVERED: Ad vector development, clinical application of these vectors in gene therapy and vaccine development, and promises that these vectors offered for future development are discussed. Also, various factors affecting their in vivo efficacy as well as the strategies being pursued to overcome these obstacles are described. EXPERT OPINION: Decades of efforts have resulted in understanding various aspects of human Ad 5 biology as well as the in vivo behavior of vectors derived from this serotype. While this vector has shown great potential, some of the limitations highlighted in recent studies have reinforced the quest for an ideal vector derived from novel Ads. Combinatorial approaches to address the various limitations of the existing vectors must be pursued to develop novel vectors with enhanced clinical potential.