Dr  Sampurna Roy  MD

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