Picornaviridae

VIRUSES

Morphology

• Very small RNA viruses
• Much antigenic variation
• Subtypes evolve and do not cross-protect
• 4 capsid proteins (VP1-VP4), with VP1 providing neutralizing target

Virulence and Pathogenesis

• Cytopathic effect of all viruses is an overnight cell rounding and pyknosis

Epidemiology

• Very resistant
• Can survive several months on fomites
• Infect via upper respiratory tract or buccal cavity and spread to target organs after viremia

Types and Subtypes

3 Main Genera:

Enteroviruses

• Swine Vesicular Disease
• Porcine Enterovirus

Apthoviruses

• Foot and Mouth Disease (FMDV)

Rhinoviruses

• Subclinical cold viruses
• Equine rhinovirus (picornavirus type 1 and 2) in rhinitis, see respiratory infections
• Bovine rhinovirus may cause mild respiratory infections