Chapter 6

Question 1

Viruses

Answer 1

a non-living pathogen, submicroscopic (very tiny), infectious agents

Question 2

Virology

Answer 2

Study of viruses

Question 3

Bacteriophages

Answer 3

viruses that infect bacteria

Question 4

Animal viruses

Answer 4

Viruses that attack animals (aka us)

Question 5

Virion

Answer 5

Single virus particle

Question 6

Capsid

Answer 6

□ Protein shell that protects the genome and accounts for virions mass

Question 7

Helical capsid

Answer 7

look like hollow tubes

Question 8

Icosahedral Capsid

Answer 8

looks like 3d polygons

Question 9

Complex Capsid

Answer 9

Deviations from icosahedral and helical capids

Question 10

Enveloped viruses

Answer 10

have a lipid-based envelope that surrounds the capsid

Question 11

Naked viruses

Answer 11

lack an envelope

Question 12

Spikes

Answer 12

protrude from the viral capsid or envelope, help viruses attach and gain entry to host cells

Question 13

Influenza A spikes

Answer 13

Hemagglutinin (HA)
Neuraminidase (NA)

Question 14

How many genes does a virus have?

Answer 14

only about 300

Question 15

Viral Genomes can be

Answer 15

RNA + DNA
Single or double stranded
Single or segmented sections
Circular or linear

Question 16

Attenuated strains

Answer 16

genetic changes that limit infectivity

Question 17

Antigenic shift

Answer 17

leads to increased infectivity or expanded host range

Question 18

Antigenic drift

Answer 18

RNA genome mutates frequently causing major changes to HA and NA spikes

Question 19

Host range

Answer 19

collection of species that viruses can infect

Question 20

Tropism

Answer 20

the turning of all or part of an organism in a particular direction in response to external stimulus

Question 21

Viral Tropism

Answer 21

ability of a particular virus to infect a particular cell or host species

Question 22

Lytic replication pathway: Steps

Answer 22

Attachment: binds to host cell
Penetration: injects genetic material to host
Replication: phage commandeers host cell factors to transcribe and translate viral genes
Assembly: ): Genome packed into capsid and phage structures assembled
Release: Bacterial cell lyses and new phages are released

Question 23

Lytic replication pathway

Answer 23

infect the host bacterial cell, build new virions, then kill the host

Question 24

Lysogenic replication pathway

Answer 24

infect bacterial cell, phage genome is incorporated in to host cell genome become prophage

Question 25

Lysogenic replication pathway: Steps

Answer 25

Attachment Penetration Phage genome is incorporated into the host cell genome forming a prophage As the cell divides, it copies the prophage Host cell is stressed, the prophage may excise itself from the host genome Phage enters the lytic replication pathway

Question 26

Animal virus replication

Answer 26

Attachment Penetration Uncoating Replication Assembly Release

Question 27

Acute infections

Answer 27

infect a host cell and new virions are made

Question 28

Persistent infection

Answer 28

viruses with replication strategies that allow them to avoid the immune system

Question 29

Persistent chronic infection

Answer 29

when virus enters but stays dormant enough to not trigger an immune response

Question 30

Persistent latent infection

Answer 30

has an immediate response, body tries to clear it but some stay in a dormant state until later

Question 31

Oncogenic viruses

Answer 31

viruses that cause cancer

Question 32

What is needed to grow virus samples?

Answer 32

host tissue, like rats for animal virus growth

Question 33

Why are diagnostic tests necessary?

Answer 33

to make sure products and tissues are safe

Question 34

Specificity

Answer 34

means that the test only detects the virus of interest

Question 35

Sensitivity

Answer 35

means the test detects very low levels of the target

Question 36

Agglutination tests

Answer 36

Purified antibodies linked to tiny latex beads

Question 37

ELISA

Answer 37

Can detect either antigens or antibodies in a sample

Question 38

Antiviral drug classification

Answer 38

Five main groups of antivirals based of what stage of the virus they attack

Question 39

Post-exposure prophylaxis (PEP)

Answer 39

Mixture of antibodies that prevent viruses from binding and entering host cells

Question 40

Tamiflu + Relenza

Answer 40

Prevents influenza A and B from budding off cell surface

Question 41

Prions

Answer 41

infectious proteins, have no genetic material thus can't replicate. Cause transmissible spongiform encephalopathies (TSEs)

Question 42

Creuzfeldt-Jakob disease (CJD)

Answer 42

Rare, degenerative and fatal brain disorder

Question 43

Creuzfeldt-Jakob disease (CJD): Categories

Answer 43

Sporadic: appears even if patient has no known signs Hereditary: patient has a family history of disease Acquired: Usually done by certain procedures if exposed to brain and tissue

Question 44

Gerstmann-Straussler-Schienker

Answer 44

An extremely rare hereditary disease, the gene found in just a few families around the world

Question 45

Kuru

Answer 45

considered an acquired prion disease