Viruses in the Heme system

Question 1

What do all viruses contain?

Answer 1

Protein and nucleic acids

- some have lipid envelope that is embedded with glycoproteins

Question 2

What are the possible genomic organization of a virus?

Answer 2

RNA both ss and ds

DNA

Question 3

What are the capsid symmetry of viruses?

Answer 3

icosahedral
spherical
helical

Question 4

What is the difference between positive and negative ssRNA?

Answer 4

Positive- the genome is Viral mRNA. Can directly make proteins

Negative- the genome is a template for Viral mRNA. Thus you must first make + RNA or mRNA to make proteins

Question 5

What are the 4 ways to describe a virus?

Answer 5

1. Genomic organization
2. Capsid Symmetry
3. Presence of Envelope
4. Tropism

Question 6

What does tropism mean?

Answer 6

What organisms do the viruses affect

• which tissues do the affect
• because specific molecular structures on viruses need specific proteins on host tissues to bind to to be affective

Question 7

What hematopoietic cells are affected by viruses?

Answer 7

All

- specific viruses affect specific cell types

Question 8

What are the steps in viral replication?

Answer 8

1. Gaining entry to host cell
2. Replicating proteins
3. Replicating nucleic acids
4. Packaging proteins and nucleic acids into virions
5. Exiting the cell
   - of note drugs are targeted to affect any of these steps

Question 9

What is the common MOA of an antiviral drug?

Answer 9

Mimic shape of nucleotide or nucleoside and plug up enzymes that are used for replication.
- drugs must have higher affinity for viral enzymes than host enzymes

Question 10

What is acyclovir and what does it mimic?

Answer 10

Antiviral that fights against some herpes viruses

• nucleoside analog which is structurally similar to guanosine
• lacks 3’ hydroxyl and thus DNA elongation cannot occur

Question 11

What is acyclovir in terms of classification and what must happen to it before it becomes active?

Answer 11

Pro-drug

- must be activated by viral thymidine kinase

Question 12

When in the cell cycle is thymidine kinase expressed and how do viruses get around this?

Answer 12

during S phase

• Viruses carry their own which push the cell into S phase and replication
• HSV does this
• allows virus to replicate in quiescent host cell

Question 13

What are the phases of viral pathogenies?

Answer 13

Acute: cell death and inflammation

Long term: malignancies and immune suppression

Question 14

What is a long term complication of Ebstein Barr Virus?

Answer 14

Oral pharyngeal cancer

Lymphoma

Question 15

What are 2 ways which viruses can cancer?

Answer 15

1. Cause cell proliferation

2. Inhibit apoptosis

Question 16

Where in the cell cycle can viral oncogenes act?

Answer 16

1. G1-S phase checkpoint
2. The regulation of cell death by apoptosis
3. The immunological synapse

Question 17

When Bid binds Bax what happens?

Answer 17

This allows for pores to form the mitochondrial membrane which then releases Cytochrome C and causes apoptosis

Question 18

When Bid binds BCL-2 what happens?

Answer 18

Doesn’t allow for release of Cytochrome C and thus no Apoptosis