The structure of coxsackievirus B3.

Abstract

Picornaviruses are small, nonenveloped, icosahedral viruses. The mature virions are approximately 300 A in diameter and the interior of the capsid shell is packed with single-stranded plus sense RNA (Mw ∼ 8×106 Daltons) (Rueckert 1990). The virus capsid is composed of 60 protomers, each consisting of one copy of the viral proteins VP1, VP2, VP3 and VP4 arranged in a T= 1 (Pseudo T = 3) icosahedral lattice (CASPAR and KLUG 1962) (Fig. 1). Atomic resolution structures have been determined for all Picornaviridae genera (Hogle et al. 1985; Rossmann et al. 1985; Luo et al. 1987; Acharya et al. 1989) with the exception of the hepatoviruses. Their structures demonstrate conservation of the eight-stranded antiparallel β-sandwich of VP1, VP2 and VP3 while VP4, which is completely interior, is not well defined in many of the structures. The regions of most structural dissimilarity for VP1, VP2 and VP3 occurs at the NH2- and COOH-terminals and the loops that connect the β-strands. Many of the differences at the COOH-terminals and β-strand loops present themselves on the surface of the virion and give each virus its unique surface topology and hence define how these viruses interact with cells and mediate early steps in the viral life cycle including receptor recognition and viral uncoating.