Introduction to Virology

Question 1

How do viruses divide?

Answer 1

They hijack the host cell’s replication machinery which allows them to assemble their components in the host cell

Question 2

What material can the viral genome be composed of?

Answer 2

DNA or RNA, but never both. This DNA or RNA can be single stranded or double stranded, and (+) or (-)

Question 3

What structures can viruses have?

Answer 3

• Icosahedral
• Helical
• Complex

Question 4

Virion

Answer 4

A single viral particle which has nucleic acid and a protein coat

Question 5

Capsid

Answer 5

• The protein coat that protects the virion’s nucleic acids
• Also carries required enzymes
• Composed of identical subunits called capsomeres

Question 6

Capsomeres

Answer 6

The identical subunits that compose the capsid

Question 7

Nucleocapsid

Answer 7

Includes the:

• Capsid
• Nucleic acids
• Enzymes

Question 8

Enveloped viruses

Answer 8

• Viruses with a lipid bilayer envelope
• Typitcally less resistant and must remain wet
• Generally transmitted through bodily fluids
• Usually susceptible to alcohol or detergent based antiseptics

Question 9

Matrix protein

Answer 9

Protein between nucelocapsid and envelope

Question 10

Naked viruses

Answer 10

Non-enveloped viruses

Typitically are resistant to drying, acids, and detergents

Question 11

Is a DNA or RNA virus heartier?

Answer 11

Typitcally DNA viruses are heartier as they are more resistant to UV light, endonucleases, etc.

Question 12

What are the main DNA viruses?

Answer 12

HHAPPPP

• Herpes
• Hepadna
• Adeno
• Polyoma
• Papilloma
• Parvo
• Pox

Question 13

What is a (+) RNA virus?

Answer 13

A virus with RNA that is similar to mRNA which can be immediately translated

Question 14

What is a (-) RNA virus?

Answer 14

An virus with RNA that is complementary to mRNA, thus it must first convert its RNA to (+) RNA before it can be translated

Question 15

Viral Attachment Proteins (VAPs)

Answer 15

Proteins that mediate attachment to the target cell by binding to a molecule on the cell surface which acts as a virus receptor

Question 16

What is the first step of viral infection?

Answer 16

Attachment

A virus must first attach to a cell to infect it

Question 17

What is the general life cycle of a virus?

Answer 17

1. Recognition
2. Attachment
3. Penetration
4. Uncoating
5. Transcription
6. Protein Synthesis
7. Genome Replication
8. Assembly/Lysis/Release

Question 18

What do VAPs often attach to?

Answer 18

• Ubiquitously expressed proteins
• Proteins with significant homology to other proteins in the body

Question 19

What goes down on HIV infected cells?

Answer 19

CD4

Question 20

Common viral vectors

Answer 20

• Insects are the main viral vectors
  
  • Mosquitoes: Yellow Fever, West Nile, and Dengue virus
  • Midges (small flys): Oropouche virus
  • Ticks: Powassan virus

Question 21

What age group is more susceptible to viruses and why?

Answer 21

Younger age groups because:

• They may not have all their vaccines yet
• They may not have been previously exposed and thus immune
  
  • Older individuals have had more previous infections and thus have immunity to more pathogens

Question 22

Are viruses easy to diagnose clinically? Why or why not?

Answer 22

No, because viruses present with very general symptoms

In some instances, a specific rash may help diagnose a particular virus

Question 23

What are some ways to get a definitive diagnosis for a virus?

Answer 23

• Tissue sample/biopsy
• Direct cytopathology
• Antibody stains
• PCR
• Serology (shows antibodies after adaptive immune response has activated)