Virus - Infection

Question 1

What are the four ways viruses can infect?

Answer 1

Latent
Persistent
Lysis
Transformationq

Question 2

What does transformation infection lead to?

Answer 2

Tumor cells with oncogenic virus development

Question 3

What is the process of transformation?

Answer 3

The virus carrying oncogenes with capacity for cancer by altering host behaviour

Question 4

What is the general infection cycle?

Answer 4

Binding surface of a host, receptor-ligand interactions, membrane fusion or receptor-mediated endocytosis, host DNA insertion, virion assembly then budding.

Question 5

How do retroviruses infect?

Answer 5

Integrate into genem and produced cDNA where viral integrase integrate them into genome

Question 6

What are examples of transformation viruses?

Answer 6

Retrovirus
Human papillomavirus

Question 7

How does Human Papillomavirus infect?

Answer 7

Contain oncogenes within own genome, integration leading to host cell machinery expression

Question 8

HPV

Answer 8

This carries oncogene E6 which inhibits P53 function

Question 9

What is lysis infection?

Answer 9

This is infection of a host with dealth, being pathogenic, like ebola

Question 10

How does Ebola infiltrate?

Answer 10

Containing glycoproteins binding Niemann-Pick C1 receptors with endocytic internalisation and endosomal transportations

Question 11

What is the intracellular life-cycle of Ebola?

Answer 11

RNA injectied into cytoplasm by glycoprotein fusion, replicated by viral polymerase enzymes

Question 12

What is persistent infection?

Answer 12

This is slow-killing of cell, with slow virus release like HIV

Question 13

How does HIV enter the cell?

Answer 13

CCR5 co-receptor aand CD4 receptor with transcriptase DNA for host integration

Question 14

How do HIV evade host immune response?

Answer 14

Dormancy of viral genome for persistence.

Question 15

How does HIV remain dormant?

Answer 15

Inhibition of host cell transcription by binding TF like P53 and NF-kB like NEF protein.

Question 16

How is HIV latency maintained?

Answer 16

Epigenetic modifications of viral promoter as well as repression of chromatin remodelling complexes that bind the HIV LTR region

Question 17

LTR region

Answer 17

This is a cis-acting regulatory element that controls the initiation and regulation of HIV transcription.

Question 18

What does prolonged HIV infection result in?

Answer 18

Replication in T Cells depleting their efficiency with progressive immune dysfunction

Question 19

Viral Integrase Enzyme

Answer 19

This catalyses viral DNA integration into the host for dsDNA incorporation into host genome forming provirus

Question 20

Provirus

Answer 20

This is the viral genetic material able to replicate, incorporated into the host genome

Question 21

How is latency reactivation stimulated?

Answer 21

Environemtnal signals where peristence triggers immune response with antibody production and immune cell activation

Question 22

What is latent finfection?

Answer 22

Virus is present but not harmful until stimulated, like Herpesvirus

Question 23

What are the steps of the Virus life cycle?

Answer 23

Attachment
Uncoating
Replication
Biosynthesis
Assembly of virus
Budding

Question 24

How does attachment occur?

Answer 24

Outer envelope surrounding the genome has proteins binding host cells, or membrane fusion

Question 25

What is the process of uncoating?

Answer 25

Release of nucleic acids with fusion of envelope with the host membrane like measles

Question 26

How can uncoating occur?

Answer 26

Endosomal acidification for enveloped viruses or proteolytic cleavage of capsid for naked viruses

Question 27

What does replication require?

Answer 27

Formation of dsDNA from the viral genome then transport into nucleus with integrase incorporation.

Question 28

How does integrase faciltiate its function?

Answer 28

Binds long terminal repeats of virus and Barrier-To-Autointegration Factor of host

Question 29

How does biosynthesis occur?

Answer 29

Binding of RNAP to promoters of the virus with epigenetic modifications

Question 30

What are the THREE CATEGORIES of viral infection?

Answer 30

Entry - Attachement, uncoating Replication - Biosynthesis Exit - Assembly and budding