1. Nature of Human Viruses

Question 1

viruses are considered _____ agents

Answer 1

filterable agents

Question 2

T/F viruses divide by binary fission

Answer 2

False. They infect a susceptible cell and take over the cellular machinery to make the cell into a virus-making factory

Question 3

T/F antibiotics and antifungals do not work on viruses

Answer 3

True

Question 4

Do most viruses have effective drugs?

Answer 4

no. most do not

Question 5

what is the size of most viruses

Answer 5

20-200 nano meters

Question 6

8% of the human genome is what

Answer 6

old retroviruses

Question 7

what does a virus do to a newly infected cell to initiate the new infection

Answer 7

disassembles the newly infected cell

Question 8

what does a virus use to complete its life cycle

Answer 8

the host cell machinery

Question 9

what is a viruses’ genetic material

Answer 9

either DNA or RNA

Question 10

what are the new virus particles made from and what are those called

Answer 10

made from newly made viral proteins in the host cell. These are called virions and they spread the virus to new cells

Question 11

what are the viral components

Answer 11

• virion
• capsid
• nucleocapsid
• viral envelope
• viral polymerases
• viral genetic material

Question 12

what are the two kinds of viral capsids

Answer 12

helical and icosahedral

Question 13

what are the characteristics of helical capsid

Answer 13

1. can vary in length depending on size of viral RNA
2. all negative sense RNA viruses have helical capsids
3. all helical capsids containing human viruses have a lipid envelope - they are all enveloped viruses
4. most do not have a rigid structure

Question 14

all negative sense RNA viruses have what kind of capsid

Answer 14

helical

Question 15

all helical capsids are naked or enveloped

Answer 15

enveloped

Question 16

icosahedral capsids can be enveloped or naked

Answer 16

can be either enveloped or naked

Question 17

what are icosahedral capsids formed from

Answer 17

viral capsid proteins

Question 18

what is meant by a naked virus

Answer 18

contains no envelope lipid bilayer

Question 19

what are viral envelopes derived from

Answer 19

derived form infected cell membranes

Question 20

what happens if the viral lipid bilayer is disrupted

Answer 20

virus cannot enter the cell

Question 21

an enveloped virus is more fragile or more resistant

Answer 21

more fragile

Question 22

a naked virus is more fragile or more resistant

Answer 22

more resistant

Question 23

how are naked viruses transfered

Answer 23

fecal-oral route

Question 24

how are enveloped viruses spread

Answer 24

• respiratory droplets
• blood
• sexual contact
• (cannot be spread fecal/orally)

Question 25

what do neutralizing antibodies do and what do they recognize

Answer 25

they prevent virus from infecting a cell and they recognize surface proteins on the virion

Question 26

neutralizing antibodies for naked viruses bind what

Answer 26

bind capsid proteins

Question 27

neutralizing antibodies for enveloped viruses bind what

Answer 27

enveloped glycoproteins embedded in the lipid bilayer

Question 28

single stranded RNA viruses have the same genome as what and are also called what

Answer 28

genome is the same sense as mRNA and are called positive-sense RNA viruses - +ssRNA

Question 29

negative-sense RNA viruses must do what

Answer 29

They must use their genomic -ssRNA as a template to make RNA

Question 30

which viruses have a segmented genome

Answer 30

BOAR - bunyavirus - orthomyxovirus - arenavirus - reovirus

Question 31

what are the types of DNA viruses

Answer 31

- linear ssDNA - linear dsDNA - circular dsDNA - circular ds/ssDNA

Question 32

what are the types of RNA viruses

Answer 32

- +ssRNA - -ssRNA - segmented -ssRNA - segmented dsRNA - circular -ssRNA

Question 33

what are the 5 types of virus-cell interactions

Answer 33

- steady state - lytic-cytocidal - latent - syncytia forming - cell-transforming

Question 34

what happens in the steady state interaction

Answer 34

- virus does not kill cell but does produce virus - productive: virus is made and is non-cytocidal

Question 35

what are the two types of lytic-cytocidal interactions

Answer 35

- lytic/cytocidal - cytopathic/cytocidal

Question 36

what happens in lytic/cytocidal interaction

Answer 36

1. virus kills cell as part of life cycle: cell death needed to release virus 2. productive and cytocidal

Question 37

what happens in cytopathic/cytocidal

Answer 37

1. virus kills cell but not part of its normal replication. makes cell sick so it cannot live. 2. productive and cytocidal

Question 38

what happens in the latent interaction

Answer 38

1. virus infects cells, does not produce virus but can reactivate 2. non-productive and non-cytocidal 3. ability to become latent is feature of herpesviruses

Question 39

what happens in the syncytia forming interation

Answer 39

infected cell can fuse membranes of neighboring uninfected cells to form a large multinucleated cell

Question 40

what happens in the cell-transforming interaction

Answer 40

if virus can transform cell = more likely to cause cancer. transforming a cell makes them immortal and able to grow on top of each other (no contact inhibition like most cells)

Question 41

which viruses cause cancer

Answer 41

- EBV (Epstein-Barr Virus) - HPV - Human Herpes Virus 8 - HTLV (Human T cell lymphotrophic virus) - HBV - HCV

Question 42

what cancer does EBV cause

Answer 42

burkitt lymphopha, nasopharyngeal carcinoma, oral hairy leukoplakia

Question 43

what cancer does HPV cause

Answer 43

cervical, anal and oropharyncx

Question 44

what cancer does Human Herpes Virus 8 cause

Answer 44

kaposi's sarcoma

Question 45

what cancer does HTLV cause

Answer 45

adult t-cell leukemia and lymphoma

Question 46

what cancer does HBV cause

Answer 46

hepatocellular carcinoma

Question 47

what cancer does HCV cause

Answer 47

hepatocellular carinoma