Antivirals

Question 1

What is the genetic material of a virus like?

Answer 1

It can be either RNA or DNA and it is in a capsid surrounding the genetic material

Question 2

What do some viruses have around the outside?

Answer 2

Lipid envelope that is decorated by envelope proteins

Question 3

What do both Hep B and Hep C have a tropism for?

Answer 3

Liver hepatocytes

Question 4

How curable are Hep B and C?

Answer 4

Hep B isn’t curable and Hep C is

Question 5

How do you treat Hep B?

Answer 5

All you can do is contain the viral replication and transform it into a chronic disease which is much less likely to cause cirrhosis, liver failure and liver cancer

Question 6

How do you know if either Hep B or Hep C needs treatment?

Answer 6

A lot of people can clear them before they get a chronic infection. So if someone gets infected, you leave it 6 months to se if they clear it but if not it requires treatment

Question 7

How is HepB treated?

Answer 7

Tenofovir- A nucleotide analogue- nucleotide reverse transcriptase inhibitor. It competes with endogenous deoxynucleotides that would be used to make up DNA- blocking DNA synthesis

Question 8

How is HepC treated?

Answer 8

Ribavirin (nucleoside analogue) and peg interferon alpha. Ribivarin competes with endogenous nucleotides and prevents synthesis of RNA
Boceprivir- protease inhibitor
Effective against Hep C genotype 1 (most common)

Question 9

What is the attachment and entry of HIV like?

Answer 9

Viral membrane proteins interact with leukocyte membrane receptors. This leads to viral capsid endocytosis

Question 10

What is the replication and integration of HIV like?

Answer 10

Within the cytoplasm there is reverse transcriptase which converts viral RNA -> DNA. The DNA is then transported into the nucleus and integrated into host DNA

Question 11

What is the assembly and release of HIV like?

Answer 11

Host cell machinery is used to produce copies of viral RNA and essential proteins. These are assembled to form new virus particles and mature virions are released

Question 12

Describe the HIV attachment and entry process?

Answer 12

HIV glycoprotein 120 attaches to CD4 receptor on the T lymphocytes
GP120 also binds to either CCR5 or CXCR4
GP41 then penetrates the host cell membrane and the viral capsid enters

Question 13

What does enfuvirtide do?

Answer 13

It binds to GP41 on HIV and blocks fusion of the virus with the host cell membrane

Question 14

What does maraviroc do?

Answer 14

Blocks the CCR5 chemokine receptor

Question 15

What are long term non-progressors in terms of HIV?

Answer 15

These are people with a polymorphism in CCR5 receptor so HIV can infect them but can’t enter their cells

Question 16

What is reverse transcription?

Answer 16

When viral RNA is converted to double stranded DNA by reverse transcriptase

Question 17

What are used to inhibit HIV replication (reverse transcription)?

Answer 17

Nucleoside reverse transcriptase inhibitors -activated by 3 step phosphorylation process e.g. Zidovudine
Nucleotide reverse transcriptase inhibitors- fewer phosphorylation steps required e.g. Tenofovir
Non-nucleoside reverse transcriptase inhibitors (NNRTI)

Question 18

How do nucleotide/nucleoside reverse transcriptase inhibitors work?

Answer 18

They compete with endogenous deoxynucleotides/deoxynucleosides thus inhibiting the action of reverse transcriptase

Question 19

How do non-nucleoside reverse transcriptase inhibitors work?

Answer 19

No phosphorylation is required, they aren’t incorporated into DNA. They bind to reverse transcriptase and cause a change in the shape of the enzyme -> blocks HIV replication e.g. Efavirenz

Question 20

What does viral integrase do?

Answer 20

It inserts the viral DNA into the host DNA

Question 21

Name an integrase inhibitor?

Answer 21

Raltegravir

Question 22

What does a virus need after it has replicated and produced a capsid?

Answer 22

It needs some other components to be synthesised to make it a complete virus that can go and infect other cells

Question 23

What is Gag?

Answer 23

It is a gene that encodes all viral structural proteins

Question 24

What does HIV protease do?

Answer 24

It cleaves Gag precursor protein releasing the proteins that go on to make up the complete virus

Question 25

What is saquinavir?

Answer 25

First generation protease inhibitor which has a low bioavailability so isn’t a very good drug

Question 26

What does low dose ritonavir do?

Answer 26

Reduces the metabolism of the protease inhibitor which allows saquinavir to reach therapeutic concentrations- they are commonly used together

Question 27

What type of virus is herpes simplex virus?

Answer 27

dsDNA virus

Question 28

What is HSV dsDNA surrounded by?

Answer 28

Tegument and enclosed in a lipid bilayer

Question 29

What is the tropism for HSV1 and HSV2?

Answer 29

HSV1- Cold sores

HSV2- Genital herpes

Question 30

How is herpes treated?

Answer 30

Acyclovir- nucleoside analogue

Question 31

Why is acyclovir very specific?

Answer 31

One of the phosphorylation steps requires viral kinases

Question 32

What type of virus is influenza?

Answer 32

Multipartite single stranded RNA virus

Question 33

What is important for the release of influenza into the host cell?

Answer 33

Envelope protein neuraminidase

Question 34

What is the tropism for influenza?

Answer 34

Nose, throat and bronchi

Question 35

What is oseltamivir?

Answer 35

Neuraminidase inhibitor