ABSTRACT

The enteroviruses are small, spherical, non-enveloped (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 2.6×106. The viruses have a protein shell containing four polypeptide chains which are elements of 60 identical, four-segmented viral capsid protein subunits called protomers.