Picornaviruses

Question 1

Decribe viral replication

Answer 1

attachment -> penetration -> uncoating -> transcription -> translation -> replication (RNA-dep RNA polymerase +/-/+) -> assembly -> release

*they must disassemble in order to direct synthesis of viral progeny

Question 2

Picornoviruses

Answer 2

• RNA viruses affecting humans and animals
• icosahedral structure, symmetrical
• linear ssRNA positive sense
• VPg (viral protein genome) attached to 5’ end of genome
• poly A attached to 3’ end
• enteroviurs, coxsackievirus, echovirus, poliovirus, rhinovirus and HAV
• attachment via capsid protein canyon floor
• penetration
• VP1 & VP4 conformation change for uncoating
• cytosol translation and cleavage of single protein for functions
• RdRp replication
• icosahedron assembly from peptide fragments
• release through lysis

Question 3

Poliovirus

Answer 3

Key:

• aseptic meningitis
• live attenuated vaccine paralysis
• PVR attachment
• oral pathogenic ingestion

Extra:

• Surface: VP1, VP2, VP3. Internal VP4 (capsid proteins)
• attachment to PVR (CD155) via capsid protein canyon floor
• VP1 & VP4 conformation change for uncoating
• oral ingestion invasion
• primary replication in peripheral lymphoid, secondary replication in CNS
• *aseptic meningitis, OPV in developing country -> poliomyelitis (paralysis)
• vaccines: live attenuated oral (OPV) - virulence reversion; *inactivated IPV

Question 4

Rhinovirus

Answer 4

• enters through direct mucosal inoculation (not aerosols)
• primary replication - upper respiratory epthelium
• secondary replication - continguos spread, rarely systemic
• common cold, pharyngitis