picorna viridae

PICORNAVIRIDAE
• enterovirus • rhinovirus
- nonenveloped viruses, 27-30 nm, resistant to ether and other lipid solvents.
- 60 subunits, RNA (30%), protein (70%).

-         genome → SS RNA, linear, (+) sense, 7.2-8.4 kb, infectious, genome linked protein (VPg).
→ Replication → cytoplasm

STRUCTURE / COMPOSITION
- capsid shell → 60 subunits, each with 4 proteins (VP1-VP4) arranged with icosahedral symmetry around a genome

-         prominent cleft or canyon around each pentameric vertex.

-         Receptor binding site located near the floor of the canyon.

-         Genome polyadenylated at 3’ end and a small coded protein (VPg) covalently bound to 5’ end.

-         Enteroviruses stable at acid PH (3.0-5.0) for 1-3 hrs , rhinoviruses are acid – labile.

-         Inactivated by heat (55⁰C for 30 min); MgCl₂ protects virus against heat inactivation.

-         Formaldehyde and oxidizing disinfectants destroy the virus.

Phenolic disinfectants not effective.