Picornaviruses Flashcards
General characteristics of picornaviruses
Icosahedral, no envelope, ssRNA
Where do picornaviruses replicate and how do they escape the cell?
Replicate in cytoplasm, escape by cell lysis (have no envelope to bud with)
Four genera of picornaviruses
Cardio-, Aptho-, Rhino- and Enteroviruses (CARE)
Which genera of picornaviruses affect humans?
Enteroviruses and rhinoviruses
Major human enteroviruses
Polioviruses, coxsackieviruses, echoviruses
Transmission and incubation period for enteroviruses
2-10 day incubation (which is short), spread by direct or indirect fecal-oral contact
What is unique about the attachment proteins of enteroviruses?
They are in a canyon on the virion surface (usually attachment proteins stick out)
What receptor do enteroviruses usually use for cell entry
A member of Ig gene superfamily
Secondary sequelae of enterovirus infection and what causes them
Myopericarditis, nephritis, and myositis. They are immune mediated (molecular mimicry)
Why are attempts to isolate enterovirus from blood usually unsuccessful?
Because by the time symptoms appear viremia is usually long over
Why should isolation of an enterovirus from stool be assessed with caution?
Because shedding may persist in feces for 4 months
How many serotypes of polioviruses are there?
Only 3. This is why development of a vaccine was a reasonable goal
What is the relationship between age and risk of paralytic disease in poliovirus infection?
Risk increases with age of infection
Two types of polio vaccines
Inactivated polio vaccine (original Salk vaccine) and Oral polio vaccine (Sabin vaccine, not used as much anymore because can regain virulence)
Up to 60 percent of infections with Coxsackievirus and Echovirus are subclinical. When symptoms do arise, which ones are most common?
Aseptic meningitis (usually mild - bad headache), rashes (esp children, eg Hand-Foot-And-Mouth disease), Acute inflammation of heart (myocarditis)
