Intro to Viruses I (Bosque)

Question 1

Name 4 shapes of viruses

Answer 1

• icosahedral nucleocapsid
• enveloped icosahedron
• helical, non-enveloped
• helical, enveloped

Question 2

T:F - viruses can be RNA or DNA and ds or ss.

Answer 2

True!

Question 3

A ss DNA virus is _____ (enveloped?)

Answer 3

non-enveloped

Question 4

A ds RNA virus is _____ (enveloped?)

Answer 4

non-enveloped

Question 5

Name 5 steps of viral life cycle

Answer 5

1. binding
2. entry
3. replication of viral nucleic acid
4. viral assembly and release

Question 6

2 methods of 1. binding

Answer 6

• absorption: virion attaches to host, releases inner tube, proteins degrade membrane, DNA from phage passed into host
• receptor mediated: enveloped viruses uses envelope to bind to receptors, trigger fusion, and endocytosed

Question 7

What is the purpose of the entry phase?

Answer 7

remove capsid that surrounds DNA

Question 8

2 types of viral infection

Answer 8

lytic and lysogenic

Question 9

Lytic cycle

Answer 9

viral genome replicated and transcribed to make vial progeny, which is released by lysis of host cell

Question 10

Lysogenic cycle

Answer 10

viral genome integrates into host chromo as prophage, which is replicated w/ host chromo and passed down

Question 11

Is viral DNA linear or circular?

Answer 11

linear when injected but circulates

Question 12

Describe 2 methods of viral assembly and release

Answer 12

Phage: encode protein that degrades membrane of bacteria so bacteria dies and virus spreads out

Budding: bud from surface of cell, which won’t kill cell

Question 13

Name 4 general patterns of disease

Answer 13

acute, chronic, latent, slow

Question 14

Prodrome

Answer 14

nonspecific early symptoms (fever, aches, chills)

Question 15

Name major routes of virus entry into host

Answer 15

skin, oropharynx, GI, respiratory tract, genitourinary

Question 16

Genitourinary defenses

Answer 16

squamous cells, pH, local humoral and cellular immunity, urine

Question 17

Respiratory tract defenses

Answer 17

Mucociliary transport system, humoral and cellular immunity, temp

Question 18

GI tract defenses

Answer 18

Low pH (2.5), humoral and cellular immunity, proteases, bile salts

Question 19

Oropharynx defenses

Answer 19

saliva, humoral and cellular immunity, mucus

Question 20

Nonspecific immune response to viral infection

Answer 20

interferons, NK cells, macrophages, innate immunity

Question 21

Specific immune response to viral infection (2)

Answer 21

AB responses/humoral and cell-mediated immunity

Question 22

AB responses/humoral works by…

Answer 22

neutralizing ab block infection; kill infected cells via complement activation

Question 23

cell-mediated immunity required for…

Answer 23

required for cell lysis in non-lytic injection; required for neutralization of enveloped viruses

Question 24

6 lab tests to detect viral infections

Answer 24

• virus culture
• detection of host anti-virus ab
• detection of viral ag
• detection of viral genomes
• detection of viral enzymes
• detection of virions

Question 25

viral evasion (3)

Answer 25

mutation, recombination, reassortment (changes via mixing of different genome segments)