Lecture 5.2: Viral Adaptations

Question 1

Viral Cell Cycle

Answer 1

• Attach
• Enter
• Replicate
• Exit

Question 2

An Overview of the Spanish Flu

Answer 2

• The 1918 influenza
• H1N1 virus with genes of avian origin
• About 500 million people or 1/3 of the world’s population was infected
• 50 million deaths worldwide

Question 3

What is the Influenza Virus?

Answer 3

• Is an orthomyxovirus
• Virions are surrounded by an envelope
• Genome is single-stranded RNA
• Allows a high rate of mutation

Question 4

What is a Serotype?

Answer 4

A variation within a microbial species, distinguished by the humoral immune response

Question 5

What are the main serotypes of Influenza Virus?

Answer 5

• A, B, and C
• Differences are based on antigens associated with the nucleoprotein

Question 6

What can Influenza A infect?

Answer 6

• Avian Hosts
• Mammalian Hosts

Question 7

What can Influenza B infect?

Answer 7

• Humans only

Question 8

Major influenza A subtypes that have infected humans during seasonal epidemics (3)

Answer 8

• H1N1
• H2N2
• H3N2

Question 9

What are the surface glycoproteins of Influenza A? (2)

Answer 9

• Hemagglutinin (HA)
• Neuraminidase (NA)

Question 10

Structure of the Influenza Virion

Answer 10

• Hemagglutinin (HA)
• Neuraminidase (NA)
• Lipid Envelope
• Protein Envelope
• M1 & M2
• RNA

Question 11

Signs and Symptoms of Influenza

Answer 11

• Sudden fever
• Pharyngitis
• Congestion
• Cough
• Myalgia

Question 12

Basic Treatments for Influenza

Answer 12

• Symptomatic care
• Anticipation of potential complications

Question 13

Best Treatments for Influenza

Answer 13

• Rest and fluid intake
• Conservative use of analgesics for myalgia and headache
• Cough suppressants

Question 14

Antiviral Medications (4)

Answer 14

• Amantidine
• Rimantadine
• Oseltamivir
• Zanamivir

Question 15

What are the 2 main processes by which mutations occur?

Answer 15

• Antigenic Drift
• Antigenic Shift

Question 16

What is Antigenic Drift?

Answer 16

Involves the accumulation of a series of minor genetic mutations

Question 17

What is Antigenic Shift?

Answer 17

Involves “mixing” of genes from influenza viruses from different species

Question 18

When does an “Epidemic” occur?

Answer 18

When there are significantly more cases of the same disease than past experience would have predicted

Question 19

What is Epidemiology?

Answer 19

To study the cause (or etiology) of disease(s), or conditions, disorders, disabilities, etc

Question 20

Structure of Covid-19/SARS-CoV-2

Answer 20

• Spike Protein
• Envelope Proteins
• Membrane Glycoproteins
• Nucleocapsid Protein
• RNA

Question 21

Common Symptoms of Covid-19/SARS-CoV-2

Answer 21

• Mild to moderate flu-like symptoms
• Fever
• Cough
• Diarrhoea
• Shortness of Breath

Question 22

Rare complications of Covid-19/SARS-CoV-2

Answer 22

• Respiratory Failure
• Systemic Inflammation
• Can lead to further consequences including Multi-Organ Damage

Question 23

Role of Spike Protein

Answer 23

Plays a key role in viral pathogenesis, evolutions, and transmission

S protein subunits and their variable conformational states significantly affect the virus pathogenesis, infectivity, and evolutionary mutation

Question 24

Mechanism of Entry of Covid-19 (7)

Answer 24

1) CoV binds to ACE2 cell receptors of epithelial cells in respiratory tract, via
Spike Protein
2) Binding of CoV receptor mediates proteolytic cleavage and fusion with host
cell membrane
3) Viral RNA released into host cell cytoplasm, viral nucleoproteins uncoat
4) Viral RNA translated to produce unglycosylated proteins
5) Proteins trafficked through Golgi, where they are glycosylated
6) Viral capsids assemble from viral RNA and N-Proteins in cytoplasm
7) Vesicles fuse with cell membrane and release CoV virions into lumen

Question 25

Origins of Covid-19/SARS-CoV-2

Answer 25

• SARS-CoV-2 has a Zoonotic Origin

Question 26

Why is Genome Sequencing in Viral Diseases

Answer 26

It can help to understand:
• The evasion mechanism of the immune system
• The development of drug resistance
• The development of precise and effective therapy
• Helps isolate different strains of the same virus

Question 27

What are the 5 consequences of an antiviral state induced by receptor activation?

Answer 27

• Inhibition of Protein Synthesis
• Viral Degradation
• Inhibition of Gene Expression
• Inhibition of Virion Assembly
• Strengthening of Cell Wall

Question 28

Which cytokine is a major activator of an antiviral state in cells?

Answer 28

Interferons