The
picornaviruses are characterized by nonenveloped virions with
icosahedral capsids 20 to 30 nm in diameter.
They contain a single-stranded RNA genome.
Two genera of picornaviruses that commonly infect humans are
the enteroviruses, which have at least 67 recognized immunologic
types, and the rhinoviruses, with more than 100 types infecting the
human.
Enteroviruses parasitise the enteric tract and
the rhinoviruses infect the nasal mucoa.
Enteroviruses have been subdivided on the basis of antigenic
relationships and differences in host range into :
Polioviruses

Coxsackieviruses
groups A and B, &
Echoviruses
|