Viral Characteristics

Question 1

What are the three components of viruses

Answer 1

1. Nucleic acid
2. Capsid (structural coat/shell)
3. Plasma membrane

Question 2

How can viruses be classified?

Answer 2

Morphology (structure of viral capsule)
Genetic make up (DNA vs RNA)
Mode of replication
Specific host cell that it invades (Cell tropism)

Question 3

Classify viruses based on genetic make up

Answer 3

DNA virus can either be SS or DS.

RNA virus can either be SS or DS. SS can either be positive sense or anti sense

Question 4

Positive sense vs anti sense

Answer 4

Characteristics of SS RNA viruses.
Positive sense means that the RNA can be directly used by the host
Anti sense means that it must be converted first before being used by host

Question 5

6 stages of infection

Answer 5

1. Attachement
2. Penetration
3. Uncoating
4. Replication
5. Assembly
6. Release

Question 6

How can viruses enter a cell?

Answer 6

Membrane fusion
-Enveloped viruses

Endocytosis
-Enveloped or naked

Direct entry
-Naked

Genetic injections
-Bacteriophage

Question 7

3 types of tropism

Answer 7

Cellular (Ex HIV)
Tissue (Respiratory vs neural)
Host (Rabbit vs human)

Question 8

How do viruses effect their host cell?

Answer 8

Will inhibit cell from DNA/RNA/protein synthesis so that the cell can make the viral particles.

Disrupt lysosomal membranes

Promotion of apoptosis if DNA is damaged or CD8 noticing strange MHC1

Carcinogenesis due to DNA change

Promotion of secondary bacterial infections if virus causes damage to basement membranes

Question 9

Outcomes of viral infection

Answer 9

Cell death, latency, carcinogenesis, clearance

Question 10

What 4 things contribute to viral pathogenicity?

Answer 10

Host range, cell tropism, mechanism of replication, method of transmission.

Question 11

Host defenses to viral infection on cellular level

Answer 11

Increase immunoproteasome activity
Upregulate MHC I and II
Destroy RNA
Disrupt protein synthesis
Increase P53 gene translation to induce apoptosis
Increase antiviral proteins (prob from IFN a)
Increase M0 and NK cell activity.

Question 12

Host defenses to viral infection on systemic level

Answer 12

Fever
Muscle aches
Taste bud function/apoptosis

Can use interferon therapy for viral infections, cancer, or MS

Question 13

Antiviral actions to prevent entry

Answer 13

Prevent attachment, prevent endocytosis, prevent uncaring

Question 14

Antiviral actions to prevent viral synthesis

Answer 14

Protease inhibitor
Reverse transcriptase inhibitor
Integrase inhibitor
Neuraminidase inhibitor

Question 15

3 types of antiviral vaccines

Answer 15

1. Live/attenuated
2. Inactivated
3. Subunit

Question 16

Attenuated antiviral vaccine

Answer 16

Elicit strongest immune response
Risky for immunocompromised patients
Require refrigeration

Ex: MMR, Varicella, polio (oral)

Question 17

Inactivated antiviral vaccine

Answer 17

Inactivated by heat or UV 
Elicit weaker immune response 
Low risk 
Very stable- does not need refrigeration 
May require boosters 

Ex: Hep A, polio (injected), and influenza.

Question 18

Subunit antiviral vaccine

Answer 18

Very safe and stable.
V small particles associated with carrier molecule
Multiple doses required

Ex: Hepatitis B

Question 19

4 types of bacterial vaccines

Answer 19

1. Live/attenuated (tb)
2. Killed (Pneumonia)
3. Conjugated (Influenza B)
4. Toxoids- vaccine against bacterial toxins. DTaP

Question 20

Toxoids bacterial vaccine

Answer 20

Vaccine against bacterial toxins. DTaP