Adenoviruses

Abstract

The 60–90 nm adenovirus virion contains a double-stranded DNA genome of approximately 35 kb surrounded by a nonenveloped icosahedral protein capsid containing 252 capsomeres and fiberlike projections from each of 12 pentagonal vertices. The fiber protein is attached noncovalently to the icosahedron by a pentameric polypeptide called the penton base. The fiber protein mediates attachment to cells and is probably an important determinant of tissue tropism. A cellular receptor known as “coxsackie B and adenovirus receptor” or CAR because it also binds coxsackie B virus has been identified for the subgroup C adenovirus types 2 and 5 [10]. The major surface protein of the virion is the trimeric polypeptide hexon. Group-reactive antigenic determinants are present on the hexon proteins from all human adenoviruses. Type-specific neutralizing epitopes are present on both the fiber and hexon proteins, with minor sites on the penton base. In addition, many adenoviruses hemagglutinate rat or rhesus monkey red blood cells; this property is related to the fiber proteins and is used to classify adenoviruses into four hemagglutination groups (Table 1).