Viruses

Question 1

Influenza Genome

Answer 1

ssRNA

Question 2

Influenza structure (main proteins) (4)

Answer 2

HA, NA, M2, M1

Question 3

Influenza cell entry (5)

Answer 3

(1) three spikes of HA bind to sialic acid on HC
(2) receptor mediated endocytosis occurs
(3) low endosomal pH triggers fusion of viral and endosome membrane - low pH induces conformational change in shape of H0 - leads to exposure of HA2 fusion peptide
(4) low pH also opens M2 proton selective channel - acidifies viral core
(5) release of vRNP so free to enter host cell cytoplasm

Question 4

Influenza transcription and replication (2)

Answer 4

(1) converted to positive sense RNA by RNA dependent RNA polymerase (RdRp)
(2) cellular RNA polymerase II binds to DNA and starts transcripiton

Question 5

Influenza immune responses (3)

Answer 5

1. induces strong IFN production - induces non-permissive state in neighbouring cells
2. humoral mediated immunity - HA specific antibodies found
3. RIG-1 is main PRR against influenza virus infections

Question 6

Influenza M2 ion channel inhibiting drugs

Answer 6

Amantadine and Rimantadine

Question 7

Influenza RNA polymerase inhibitor

Answer 7

Favipiravir

Question 8

Influenza NA inhibitor

Answer 8

Zanamivir

Question 9

Herpes Genome

Answer 9

dsDNA

Question 10

HHV-1

Answer 10

Herpes simplex - cold sore - trigeminal ganglion infection (60% US prevalance)

Question 11

HHV-2

Answer 11

Herpes simplex - genital herpes - sacral ganglion (20% US prevalence)

Question 12

HHV-3

Answer 12

Varicella (chicken pox) Zoster (shingles) virus

Question 13

HHV-4

Answer 13

Epstein Virus

Question 14

Herpes Cell entry (6)

Answer 14

1. gC and gB bind to heparan sulfate
2. gD binds to HVEM, nectin-q, or 3-0 sulfated heparan sulphate
3. nectin receptors produce cell-cell adhesion
4. gD (once bound to HVEM), changes conformation and interacts with gH and gL
5. interaction results in hemifusion state
6. gB interaction with gH/gL results in creation of entry pore

Question 15

Herpes Virus immune evasion (4)

Answer 15

1. Block MHC I expression and promote degradation
2. inhibit proteosome
3. block TAP transporter
4. block expression of activatory NK ligands

Question 16

Herpes virus treatment (1)

Answer 16

acyclovir and glancyclovir - thymidine anlogues

Question 17

HIV genome

Answer 17

ssRNA

Question 18

HIV cell entry (4)

Answer 18

1. Gp120 binds to CD4
2. co-receptor binding (CCR5/CXCR4)
3. interaction between CD4 and gp120 allows exposure of fusion proteins in the gp41 subunit - inserts into host cell membrane and acts as a tether
4. mixing of lipids which compose the membranes and entry

Question 19

HIV replication (4)

Answer 19

Uses Reverse Transcriptase

1. polymerase center uses host cell tRNA to use viral RNA as a template - RNA-DNA strand formed
2. RNaseH center used to degrade RNA component
3. dsDNA formed
4. integrase effectively cuts and pastes the viral DNA in to the gebome

Question 20

HIV transcription

Answer 20

1. immediately after replication, only Tat and Rev produced
2. Tat increases transcription of HIV-1 genes by recruiting cellular transcription factors
3. primary RNA transcripts undergo extensive splicing - results in over 40 different mRNAs

Question 21

HIV antiviral drugs (3)

Answer 21

Tak-220 - prevents binding of CCR5 to gp120
Enfuvirtide - targets membrane fusion
Zidovudine - thymidine analogue which prevents action of RT

Question 22

Hepatitis Genome

Answer 22

dsDNA