Structure and Assembly of Adenoviruses

Abstract

Adenoviruses, this year celebrating the 30th anniversary of their discovery by man, are still in the foreground of scientific interest. With their multiple genes they are in fact one of the outstanding model systems for studying gene expression and its control in mammalian cells, as evidenced in numerous reviews (PHILIPSON et al. 1975; DOERFLER 1977; GINSBERG 1979; PHILIPSON 1979; NEVINS and CHEN-KIANG 1981; FLINT and BROKER 1981). The advances in the biochemistry and molecular biology of these viruses have not yet been balanced by equal progress in ultrastructural research of the virion itself and its assembly in the cell, although the architectural problems have recently received attention (PEREIRA and WRIGLEY 1974; EVERITT et al. 1975; BROWN et al. 1975; CORDEN et al. 1976; BURNETT et al. 1978; NERMUT 1980). Although adenoviruses are recovered from several hosts, including among others humans, monkeys, mice, and birds, with distinct but small differences in single polypeptides, the virion itself is of remarkably uniform morphology (Fig. 1). They all have an icosahedral shell and the capsid is built up from 252 capsomers, comprising 240 hexons, each surrounded by six neighboring capsomers, and 12 pentons at the vertices of the icosahedron each surrounded by five peripentonal hexons (VALENTINE and PEREIRA 1965; GINSBERG etal. 1966). Inside the capsid is a nuclear core containing the viral DNA and at least three viral proteins.