Ch 22 Exam 4

Question 1

introduced species

Answer 1

species released into a non-native environment

Question 2

What must all viral cells do within host cells?

Answer 2

They must replicate WITHIN host cells

Question 3

productive infection

Answer 3

new infectious viruses made after virus entry into host

Question 4

abortive infection

Answer 4

a few, if any viruses are made after virus entry into host

Question 5

what type of infection results in infectious disease?

Answer 5

productive infection

Question 6

What does the overall outcome of viral infection depend on?

Answer 6

the replication of a virus
the immune response of the host

Question 7

acute infections
(give an example)

Answer 7

viral infections that occur suddenly (most of viral infections we experience)
(rhinovirus infection)

Question 8

latent infection
(give an example of a virus that exhibits latency)

Answer 8

virus remains in the host and replicates over the course of a long time (genome remains in infected cells)

herpesvirus

Question 9

episome
LATs

Answer 9

circular genome of viral DNA separate from the host genome (affiliated with latent infection)

(latency-associated transcripts) transcribed during latency

Question 10

What is the relationship between LAT expression and viral gene expression

Answer 10

During reactivation, an increase in VIRAL gene expression results in a decrease in LAT

Question 11

What can cause viruses to switch from latency

Answer 11

stress events, UV light, studying for exams, menstruation (women) (basically depends on the health of the host)

Question 12

persistent/ chronic infections

Answer 12

the continuous production of viruses

unlike acute where there is RAPID recovery, host does not clear the virus in a reasonable amount of time

Question 13

For persistent/chronic infections to occur, what must happen?

How may a virus do this?

Answer 13

virus must be able to replicate in the presence of host innate/ adaptive immune responses

weakening immune response
mutation that alters replication (altering cathepsin B)

Question 14

How must a virus be transmitted?

Answer 14

must be expelled from original host
must be infectious until new host is found
mast have access to cells within new host

Question 15

Give examples of common horizontal transmission strategies

zoonotic?

Answer 15

respiratory (rhinoviruses, influenza)
fecal-oral (polioviruses, hepatitis A)
sexual(HIV, human papillomaviruses

Ebola

Question 16

how may vertical gene transfer occur? Give an example.

Answer 16

blood may be transferred from mother to child, or milk form mother to child (rubella, HIV, hepatitis B and C)

also may be through germ cells that make sperm/ egg (like mammary tumor virus of mice)

Question 17

endogenous retrovirus
(why is this important)

Answer 17

when a retrovirus inserts itself in sperm or egg, combining with the DNA of the gametes

viruses can be inherited through generations

Question 18

What is zoonosis (don’t overthink it bud)

Answer 18

a disease resulting from the zoonotic transfer of viruses

Question 19

True or False: Humans are typically dead-end hosts

Answer 19

True

Question 20

how may viruses indirectly/directly lead to auto-immunity

Answer 20

a viral infection may cause the immune system to attack itself

molecular mimicry (immune response for virus attacks host)

Question 21

transformation
tumorigenesis

Answer 21

changes within a cell that cause it to be out of control

formation of a tumor (not normal growth of tissue)

Question 22

oncogenes

Answer 22

genes capable of causing animal cell transformation

Question 23

Are viral oncogenes needed for cell replication?

Answer 23

Yes

Question 24

papillomas

how does it cause tumor formation

Answer 24

skin tumors/ warts

stimulates the S phase of quiescent cells (cells that don’t actively divide) which are keratinocytes

Question 25

What proteins do papillomas affect? What do these proteins do?

Answer 25

tumor suppressors Rb (binds to E2fs stopping S phase) and p53 (makes p21, which induces apoptosis)

Question 26

How do papillomas specifically prevent tumor suppressor proteins? What technique (using an antibody to precipitate antigen) can be used to detect this?

Answer 26

HPV proteins E6 binds Rb and E7 binds p53 (therefore preventing p21 production) immunoprecipitation (IP)

Question 27

Why is cancer associated with certain strains of HPV?

Answer 27

proteins of oncogenic strains bind to tumor suppressor proteins with greater affinity than non-onco. oncogenic strains target effectively

Question 28

True or False: Many human cancers have been associated with adenovirus infections

Answer 28

False (they usually lead to apoptosis)

Question 29

For tumorigenesis to occur, what proteins must be inactivated?

Answer 29

Rb and p53

Question 30

how may hepatitis c virus cause cancer?

Answer 30

most likely a byproduct of chronic inflammation rather than directly from the RNA-containing virus

Question 31

protooncogenes

Answer 31

genes that code for proteins involved in cell growth

Question 32

how may protooncogenes convert to oncogenes?

Answer 32

viral DNA inserts near protooncogene, causing a change retroviruses introduce oncogenes to normal cells (cis-acting retroviruses)

Question 33

cis-acting retroviruses type 7 transducing retroviruses

Answer 33

retroviruses that change oncogene when integrated retroviruses that introduce oncogenes to other cells