H. Animal Virus Replication Overview

Question 1

list of steps of virus replication

Answer 1

1 Attachment (adsorption) 2 entry and uncoating 3 replication of viral components 4 assembly, exit from host cell 5 +/- maturation

Question 2

1. attachment

Answer 2

chance collision of viron and host cell. larger # of virions. greater chance of infection

Question 3

1. how does attachment occur

Answer 3

surface molecule on virion bind specific receptor on host cell. receptors have fn for host cell. many members of Ig superfamily. eg Rhinovirus uses ICAM as receptor

Question 4

how can receptors be identified

Answer 4

using monoclonal antibodies. then see if virus can still infect tissue

Question 5

2. Entry and uncoating. what is uncoating

Answer 5

general term for release of genome from virus

Question 6

2. Entry of naked virus

Answer 6

after attachment, the virion is taken up by endocytosis. genome will be released from endosome

Question 7

2. Entry of envelope virus (2 ways)

Answer 7

endocytosis- envelope fuses w/endosomal membrane. contents are released in cytoplasm where they are uncoated. fusion-viral envelope fuses w/PM, releases capsid in cytoplasm where uncoated

Question 8

3. replication of viral component

Answer 8

mRNA synthesis and genome synthesis depends on type of genome. both required virally encoded enzymes b/c host cells don’t have these enzyme

Question 9

3. replication, name an enzyme host cells don’t have

Answer 9

+RNA to -RNA

Question 10

3. replication, polymerase names refer to

Answer 10

type of nucleic acids used as template and type synthesised. eg DDRP DNA dependent template and RNA is nucleic acid synthesized

Question 11

3. Spike proteins are synthesized by

Answer 11

RER and inserted to PM

Question 12

4. Assembly

Answer 12

capsid proteins self assemble enclosing the genome

Question 13

5. Exit of naked viruses

Answer 13

naked viruses accumulate in the cytoplasm. cause cell lysis releasing viral particles

Question 14

5. Exit of envelope viruses

Answer 14

if virus does not have matrix proteins, capsid binds to PM. if matrix proteins then bind to inner surface of PM then capsid binds to matrix. both ways capsid exit by budding

Question 15

5. exit define budding

Answer 15

capsid takes piece of PM containing spike proteins as an envelope

Question 16

6. Maturation

Answer 16

some assembled viruses are not infectious. specific proteins must be cleaved by viral protease. occurs late in assembly or after release of immature viral particle. once matured called virion