ABSTRACT
The enteroviruses are small, spherical, nonenveloped (naked) viruses that have icosahedral symmetry and a diameter of 27 to 30 nm.The virion is composed of a core of single-stranded RNA of about 7500 bases, with a molecular weight of 2.6106daltons. The viruses have a protein shell containing four polypeptide chains, which are elements of 60 identical, four-segmented viral capsid protein subunits called protomers.
