ABSTRACT
The enteroviruses are small, 24-to 30-nm particles with a single-stranded RNA genome. They are classified as Picomaviridae. In 1957, several groups of viruses (polio, Coxsackie, and echo) were combined into the enterovirus genus. Although polioviruses caused severe epidemics of paralytic disease in the first half of the 20th century, successful vaccine programs have eliminated polio from the Western hemisphere, and a multinational effort is under way to eradicate polio from the world. This leaves the nonpolio enteroviruses as the major neonatal viral infection during the summer months in the United States. Enteroviruses of human origin include the following:
l. Coxsackie viruses A: 23 types and several variants (Coxsackie viruses AlA24 [Coxsackie virus type A 23 is the same virus as echovirus 9])
2. Coxsackie viruses B: types Bl-B6 3. Echoviruses: 31 types (types 1-33 [echovirus 10 has been reclassified as re-
ovirus type 1, and echovirus 28 as rhinovirus type lA]) 4. Enterovirus types 68-71
All enteroviruses contain four structural proteins: VPl, VP2, VP3, and VP4. The variability of these structural proteins accounts for the unique serotypes. Although minor mutations occur rapidly, the emergence of new serotypes is rare. Since the enteroviruses lack a lipid envelope, they resist inactivation by alcohol and ether.
