Viruses

Question 1

What is a virion?

Answer 1

• the infectious particle of a virus
  
  • no metabolism outside of host cells
  • bind to host cells and infect them

Question 2

What is a progeny?

Answer 2

-newly synthesized virions that are released by infected (host) cells

Question 3

What is the structure of a naked virion?

Answer 3

• (non enveloped)
• nucleic acid (DNA or RNA)
• protein capsid
• protein spikes (proteins or glycoproteins)

Question 4

What is the structure of an enveloped virion?

Answer 4

• lipid envelope
• nucleic acid (DNA or RNA)
• protein capsid
• protein spikes (glycoproteins)

Question 5

What is a nucleocapsid made of?

Answer 5

-capsid+ nucleic acids

Question 6

Where are the matrix proteins located?

Answer 6

-inside the capsid

Question 7

Where is the tegument located?

Answer 7

-between the envelope and capsid (some enveloped viruses)

Question 8

What kind of proteins are sometimes found in the matrix or tegument of virions?

Answer 8

• viral enzymes; necessary for virion to subvert (take over) a host cell

Question 9

What makes up the viral genome?

what are the 2 types?

Answer 9

Nucleic acids

-monopartite and segmented

Question 10

What is a monopartite? Example

Answer 10

• a single molecule of nucleic acid

- coronaviruses have 1 RNA molecule inside each virion

Question 11

What is a segmented virus? Example?

Answer 11

• genome consisting of several nucleic acid molecules

- rotaviruses have 11 RNA molecules inside each virion

Question 12

What is the typical size of a virion?

Answer 12

22-450 nm in diameter

Question 13

Which cell is smaller than a virion?

Answer 13

-hemoglobin; 15 nm

Question 14

What are the 7 steps the viral life cycle?

Answer 14

1) adsorption
2) Entry
3) uncoating
4) subversion
5) synthesis
6) assembly
7) exit/release
7) exit/release

Question 15

What is adsorption?

Answer 15

-virion spike proteins bind to protein on host cell (viral receptors)

Question 16

What is entry? What are some strategies viruses use to enter a cell

Answer 16

• nucleic acids (and other parts) enter host cell
  
  • fusion (enveloped)
  • receptor-mediated endocytosis
  • injection of genome

Question 17

What is uncoating?

Answer 17

• nucleic acids are exposed in the cytoplasm of the host cell

Question 18

What is subversion?

Answer 18

-virus takes control of host cell to be reprogrammed to build more virions

Question 19

What are the 2 goals of viral synthesis?

Answer 19

1) make copies of viral genome/nucleic acids

2) make viral proteins
- capsid
- spike
- viral enzymes

Question 20

Look to notes on the process of viral synthesis

Question 21

What are 2 viral exit (release) strategies?

Answer 21

• enveloped viruses bud (allows gradual, prolonged release) to exit
• naked viruses exit by lysis (release of large numbers in a short period)

Question 22

What kind of viruses increase the risk of cancer?

Answer 22

-oncoviruses

Question 23

How do some viruses increase the risk of cancer?

Answer 23

-the reprogramming of the host cell allows it to escape the normal controls that prevent overgrowth, promoting cancer.

-

Question 24

Explain what host range is regarding viruses

Answer 24

• all of the species of hosts that it can effect
  
  • ex. Influenza > people, pigs, chickens
  -Zika virus > mosquitos, people, monkeys, other mammals

Question 25

What is tissue tropism?

Answer 25

• all of the cells/ tissues in a host that can be infected

- rabies > muscle cells, nervous cells, salivary glands

Question 26

Characteristics of human herpes viruses

Answer 26

+/- DNA viruses

Enveloped

Complex tegument

Latent infections

Not a retrovirus

Question 27

What are the 8 human herpes viruses?

Answer 27

1) herpes simplex 1 (STD)
2) herpes simplex 2
3) Varicella zoster (chicken pox, shingles)
4) Epstein- Barr (rash, swollen tonsils)
5) Cystomegalovirus (can lead to stillbirth, liver, CNS damage)
6) Roseola (fever> rash)
7) HHV 7 (fever>rash)
8) Kaposi Sarcoma Associated

Question 28

What is seroprevalence?

Answer 28

• measures antibodies in a large group

- % of people who have antibodies vs specific pathogen

Question 29

What kind of virus is herpes simplex?

Answer 29

-latent virus

Question 30

What do you need to culture a virus in a lab?

Answer 30

-host cells

Question 31

What are some cytopathic effects of cells

Answer 31

• Plaques= missing host cells
• syncytiums= fusion of host cells
• enlarged cells

Question 32

Why don’t bacterial or fungal antibodies work on viruses?

Answer 32

• viruses use host cell enzymes to carry out reproductive process
• viruses are minimalists
• viruses use human cells

Question 33

What are 3 antiviral therapies?

Answer 33

• nucleoside analogs
• interferons
• budding inhibitors

Question 34

Name a nucleoside analog and how it works

Answer 34

• Acyclovir; becomes phosphorylated and is incorporated into DNA rep, creating a dead end

Question 35

What is a cytokine?

Answer 35

-protein release by human cells; part of immune system

Question 36

What is an interferon?

Answer 36

• type of cytokine that activate inherent antiviral defenses_

Question 37

What are the different ways a interferon can defend against a virus? (3)

Answer 37

• attack viral mRNA
• slow protein synthesis
• increase MHC display

Question 38

Name a budding inhibitor and the virus it is used to treat. How does it work?

Answer 38

• Neuraminidase inhibitor treats influenza.

- it greatly slows viral spread giving an advantage to the immune system

Question 39

Look at notes for Life Cycle of HIV