Intro to Viruses

Question 1

Size of a virus vs. a bacteria

Answer 1

Viruses are smaller than the smallest bacteria

Question 2

Viruses (can or cannot) be seen w/ a light microscope

Answer 2

Cannot

Question 3

What type of nucleic acids to viruses have?

Answer 3

Either DNA or RNA, but NOT BOTH

Question 4

Protein coating of a virus is called a ____?

Answer 4

Capsid

Question 5

A capsid is composed of identical protein subunits called ____

Answer 5

Capsomeres

Question 6

Some viruses have a lipid/protein membranous outer coating called ____

Answer 6

Envelope

Question 7

Glycoprotein spikes or projections that protrude from the envelope are called ____

Answer 7

Peplomers

Question 8

Viruses w/o envelopes are called ____

Answer 8

“Naked”

Question 9

2 configurations a capsid can have

Answer 9

• Icosahdral (cubic)

- Helical

Question 10

Nucleic acid + capsid = ?

Answer 10

Nucleocapsid

- Infectious form of “naked” viruses

Question 11

Nucleic acid + capsid + envelope = ?

Answer 11

Virion

- Infectious form of enveloped viruses

Question 12

Viral replication occurs only w/in a ____ ____

Answer 12

Living cell

Question 13

How are viruses classified?

Answer 13

• Nucleic acid type
• Virus size, configuration, and composition
• Serological cross-reactivity of group Ags

Question 14

6 steps of viral replication

Answer 14

1. Attachment
2. Penetration
3. Eclipse
4. Replication
5. Maturation
6. Release

Question 15

What happens in the attachment stage of viral replication?

Answer 15

Virus binds to receptors on cell surface

Question 16

What happens in the penetration stage of viral replication?

Answer 16

Virus enters cell (by engulfment, though fusion of cell membrane and viral envelope, or by direct passage)

Question 17

What happens in the eclipse stage of viral replication?

Answer 17

Nucleic acid is freed from capsid; intact virion is not detectable. The protein coding of the nucleic acid is often inserted into the cell membrane.

Question 18

What happens in the replication stage of viral replication?

Answer 18

Host cell manufactures viral nucleic acids and capsid proteins (at spearate locations w/in infected cells)

Question 19

What happens in the maturation stage of viral replication?

Answer 19

New nucleocapsid or virons are assembled

Question 20

What happens in the release stage of viral replication?

Answer 20

New nucleocapsids or virions are released from the host cell (budding or cell lysis)

Question 21

What are the protein substances produced by virus-infected cells that act on infected and surrounding cells to interfere w/ viral replication

Answer 21

Interferons

Question 22

Do interferons act on cells or viruses?

Answer 22

On cells NOT VIRUSES!

Question 23

Interferons are most effective on host cells from same ____

Answer 23

Species

Question 24

Why are antibiotics not effective against viruses?

Answer 24

Viruses do not have target components

Question 25

Papilloma virus aka ____

Answer 25

Wart virus (known for genital warts)

Question 26

Is there a vaccine available for papilloma virus?

Answer 26

Yes

Question 27

Papilloma virus | - Rapid Ag tests available or not?

Answer 27

No

Question 28

Papilloma virus | - Does or doesn't grow in cell culture?

Answer 28

No

Question 29

Papilloma virus | - What approach is used for lab diagnosis?

Answer 29

Molecular approach | - Use on materal from pap smear or other source

Question 30

Measles | - Clincal presentation

Answer 30

- Rash on trunk and elsewhere - 7-10 days of fiver - Complications (i.e., encephalitis)

Question 31

Mumps | - Clinical presentation

Answer 31

- Swollen parotid glands - 7-10 days of symptoms - Complications (i.e,. testicular involvement, CNS symptoms)

Question 32

Measles and mumps | - What happened when U.S. introduced vaccine (MMR)?

Answer 32

Virtually eradicated in the U.S. but recent resurgences

Question 33

Measles and mumps | - Rapid Ag detection available?

Answer 33

No

Question 34

Measles and mumps | - Does it grow in cell culture?

Answer 34

Yes

Question 35

Measles and mumps | - Ab detection useful?

Answer 35

Yes, for immune status determinations

Question 36

Rabies virus | - Infection is "____" → CNS symptoms resulting in inability to what?

Answer 36

"Hydrophobia"; swallow, breathe

Question 37

Rabies virus | - Chances of living w/ rabies

Answer 37

Little chance, routinely fatal

Question 38

Rabies virus | - How does this virus travel in the body?

Answer 38

Travels through nerves from bite site to brain

Question 39

Rabies virus | - Rapid Ag detection available?

Answer 39

No

Question 40

Rabies virus | - Does it grow in cell culture?

Answer 40

Not well

Question 41

Rabies virus | - How is it best diagnosed in humans?

Answer 41

Biopsy of nerve near bite site

Question 42

Rabies virus | - How is it diagnosed in animals?

Answer 42

Examine brain for Negri bodies

Question 43

Smallpox (Variola) virus | - How is it transmitted?

Answer 43

Person to person

Question 44

Smallpox (Variola) virus | - Symptoms

Answer 44

- High fever | - Large vesicular lesions

Question 45

Smallpox (Variola) virus | - Fatal in 10-30% of cases due to ____

Answer 45

Toxemia

Question 46

Smallpox (Variola) virus | - Rapid Ag detection available?

Answer 46

No

Question 47

Smallpox (Variola) virus | - Does it grow in cell culture?

Answer 47

Yes; do not attempt to isolate in hospital lab!!!!

Question 48

Smallpox (Variola) virus | - What to do for smallpox diagnosis?

Answer 48

CALL CDC!!!