picornaviruses

Question 1

characteristics of picornaviruses

Answer 1

-simple
- non-enveloped virions
small viruses with small RNA (pico-RNA) genome
+ssRNA

Question 2

examples of picornaviruses

Answer 2

FMDV, polio, rhinovirus, hepatitis A

Question 3

common features in order picornavirales

Answer 3

pseudo T=3 virus particles
+ strand RNA often with VPg and polyAtail
polyprotein
Helicase-protease-RDRP unit (in this order)

Question 4

poliovirus virus particle

Answer 4

non-enveloped, icohedral virus particle (virion)
virion T=1 but pseudo T=3 particle. triangle from VP1/2/3
hexamer and pentrameric symmetry

Question 5

Why psuedo T=3

Answer 5

originally one type of CP, evolution changed into 3 distantly related.

Question 6

IRES

Answer 6

internal ribosome entry site. two type I (6 stem loops enteroviruses/polio), type II (12 stem loops FMDV and EMCV)

Question 7

function of IRES

Answer 7

binds to cleaved eIF4G and initiates translation (viral proteinases cleave eIF4G)

Question 8

viral proteases in picornaviruses

Answer 8

FMDV: L (leader) protease cleaves itself from VP4 and cleaves EiF4G
enterovirus 2A protease cleaves at the P1-P2 border and cleaves EIF4G
3C conserved in all picornaviruses

Question 9

3C protease in picornaviruses

Answer 9

cleaves P1/2/3 by uncleaved 3C. 3C cuts at its own N-terminus in 3AB and 3CD. 3CD cleaves P1 and P2. 3CD -> 3C and 3C, 3C cleaves remainder of P2 and P3

Question 10

FMDV 2A

Answer 10

2A is a ribosome skipping element

Question 11

structure of picornaviruses

Answer 11

P1: capsid protein VP0 to VP4.

P2 and P3: replication

Question 12

P1 region

Answer 12

Capsid maturation. Immature capsid: VP0, VP1, VP3. only when RNA is inside: VP0 cleaves into to VP2 and VP4

Question 13

picornavirus entry

Answer 13

poliovirus enters through conformational changes after receptor binding at cell membrane
Rhinovirus and FMDV: receptor mediated endocytosis

Question 14

P2 and P3 regions

Answer 14

replication:
2B,2C,3A are responsible for the vesicles
3D: polymerase
3B: VPg. RNA strand is synthesis when VPg is uridylated to VPg-UU, positioned on template and 3D elongates the strand. polyA is part of the genome.

Question 15

picornavirus host shut off

Answer 15

mediates protein synthesis shut off from hosts. uses the proteases (2A and 3C) mostly to cleave host proteins like polymerase or translation factors to shut off host.