Biology of Adenovirus Cell Entry

Adenoviruses contain an icosahedral coat and a nucleoprotein core of viral deoxyribonucleic acid. Mastadenoviruses infecting mammals are composed of several hundred different types. Human adenoviruses are the most widely used vectors in clinical applications, mainly for killing cancer cells and vaccinations. They are physically and genetically stable and are safe for use in humans. We discuss the state of the art in adenovirus entry, a key process for infection and immunity. Entry requires hundreds of host factors, but mechanisms are known for only some of them. It involves coating the virus with soluble serum or tissue factors, using receptors that initiate stepwise uncoating, signaling, endocytic uptake, and lysis of the endosomal membrane. Cytoplasmic transport and immunity, together with complete uncoating, determine nuclear import and transcriptional activation of the viral genome. We conclude with perspectives and a discussion of outstanding questions in the field.