Viral Pathogens: Classification, Biology, Diseases I

Question 1

What are the two types of virus?

Answer 1

RNA

DNA

Question 2

What are the four structures of viral genomes?

Answer 2

SsRNA
DsRNA
SsDNA
DsDNA

Question 3

What are the structure of RNA genomes?

Answer 3

Linear and segmented

Question 4

What are the structure of DNA genomes?

Answer 4

Linear or circular

Question 5

What is the central dogma?

Answer 5

DNA polymerase facilitates replication
RNA polymerase facilitates transcription
Ribosomes facilitate translation

Question 6

How do viruses use the central dogma?

Answer 6

Reverse transcriptase reverses RNA polymerase

RNA dependant RNA polymerase reverses RNA replication

Question 7

What is the baltimore classification?

Answer 7

Classes of genetic material present in the virion

Question 8

What are group I viruses made up of?

Answer 8

DNA +/-

Question 9

What are group II viruses made up of?

Answer 9

DNA+

Question 10

What are group III viruses made up of?

Answer 10

RNA +/-

Question 11

What are group IV viruses made up of?

Answer 11

RNA+

Question 12

What are group V viruses made up of?

Answer 12

RNA -

Question 13

What are group VI viruses made up of?

Answer 13

RNA+

Question 14

What are group VII viruses made up of?

Answer 14

DNA+/-

Question 15

What does the HIV-1 outer envelope consist of?

Answer 15

Lipid bilayer with protruding Env spikes

Question 16

What lies inside the HIV-1 envelope?

Answer 16

Shells of Gag proteins

Question 17

What associates with the membrane?

Answer 17

Matrix

Question 18

What does the capsid form?

Answer 18

Conical capsid

Question 19

What does the viral RNA genome form?

Answer 19

Nucleocapsid

Question 20

What does the envelope consist of and covered by?

Answer 20

A trimer of gp41 and gp120 peptide subunits

Covered with glycans

Question 21

What are the two membrane proteins necessary for HIV-1?

Answer 21

CD4 and a chemokine receptor

Question 22

What are the steps in HIV entry?

Answer 22

Native primer
CD4 binding and T20 binding site exposure (due to a conformational change)
CoR binding and fusion peptide insertion
6-helix bundle formation and membrane fusion

Question 23

What is HIV-1 tropic for?

Answer 23

CD4 expressing cells

Question 24

What are the early phases of HIV-1 infection?

Answer 24

Fusion
Uncoating and reverse transcription
Intracellular trafficking
Nuclear entry

Question 25

What is reverse transcriptase a heterodimer of?

Answer 25

P66 and p51 subunits

Question 26

What are the three enzymatic properties of reverse transcriptase?

Answer 26

RNA dependant DNA polymerase RNAse H DNA dependant DNA polymerase

Question 27

What is reverse transcription mediated by?

Answer 27

Reverse transcriptase

Question 28

What does reverse transcriptase act as?

Answer 28

Polymerase to make the RNA template from the RNA genome

Question 29

How does the HIV DNA insert itself into the host chromosome?

Answer 29

Ends of viral DNA have specific sequences that are recognised by integrase enzymes Sticks and pastes the viral DNA into cellular DNA

Question 30

How does the integrase enzyme Stick and paste the viral DNA into cellular DNA?

Answer 30

Bending the viral DNA round into very close contact with the cellular DNA

Question 31

What binds HIV-1 integrase and facilitates chromatin targeting?

Answer 31

LEDGF/P75

Question 32

What does the HIV-1 promoter contain?

Answer 32

Binding sites for transcription factors that are present in T-lymphocytes

Question 33

What does the HIV-1 promoter do?

Answer 33

Recruits cellular proteins to the viral genome that are required for mRNA transcription

Question 34

What is the first thing that gets produced by the genome and what does it do?

Answer 34

Tat protein | Specifically binds to the RNA and enhances RNA replication

Question 35

What does the HIV-1 rev protein mediate?

Answer 35

Nuclear export of a spliced viral RNA

Question 36

What does HIV-1 rev protein form?

Answer 36

A feedback loop wherein it comes back into the nucleus and promotes the nuclear export of the RNA viral genome over cellular RNA

Question 37

What does REV protein interact with to promote viral genome replication?

Answer 37

Crm 1 and RRE RNA

Question 38

What does dimerisation of the un spliced viral RNA allow?

Answer 38

Packing of two genomes in the virus

Question 39

What is the kissing loop complex?

Answer 39

Two of the same sequence brought together

Question 40

What is gag-pol protein generated by?

Answer 40

7 ribosomal frameshifting induced by a slippery sequence on RNA hairpin structure

Question 41

What is myristoylation?

Answer 41

Post-translational modification of glycines in the MA domain of Gag

Question 42

What does myristoylation mediate?

Answer 42

Association with the plasma membrane

Question 43

What causes the polyprotein to be made, myristoylated and transferred to the cell surface?

Answer 43

Tsg 101

Question 44

What is hijacked by HIV to perform membrane abscission during viral release?

Answer 44

ESCRT

Question 45

What is abscission?

Answer 45

Combining proteins and RNAs into a capsid, which essentially pushes the new capsid into the extracellular space

Question 46

What does Gag processing generate?

Answer 46

Mature viruses