Lecture 20 - Rotavirus

Question 1

What viral family does rotavirus belong to?

Answer 1

Reoviridae

Question 2

What diseases does rotavirus commonly cause and in which individuals?

Answer 2

diarrheal disease in infants and young children

Question 3

What type of genome does rotavirus have?

Answer 3

dsRNA

Question 4

What are Reoviruses that infect humans and animals known as?

Answer 4

rotaviruses

Question 5

What type of particle is the rotavirus virion?

Answer 5

Triple-Layered Particle - surrounds genome

Question 6

What is the rotaviral protein NSP4?

Answer 6

enterotoxin – modulates intracellular Ca2+ levels

Question 7

What cells are susceptible and permissive to rotavirus? (What cells does rotavirus infect?)

Answer 7

mature, non-dividing enterocytes of the villi in small intestine

Question 8

What are 3 viral receptors on host cells that rotaviral protein VP4 attach to?

Answer 8

sialic acid | integrins | tight-junction proteins (SIT)

Question 9

How are progeny virions released through the cell?

Answer 9

lysis

Question 10

In what bodily product are rotaviruses shed?

Answer 10

in the stool

Question 11

What is the mode of transmission of rotaviral infections?

Answer 11

fecal-oral route, close person-to-person contact

Question 12

Who are the most susceptible to rotaviral infections and why?

Answer 12

infants and young kids because they are at the stage where they put things in their mouths, have close contact with others

Question 13

Which cells in the body lyse first due to rotaviruses?

Answer 13

enterocytes

Question 14

What does rotavirus pathogenesis induce?

Answer 14

secretory and osmotic diarrhea lasting a short time

Question 15

What causes the osmotic diarrhea?

Answer 15

due to malabsorption (enterocyte death or damage)

Question 16

What causes the secretory diarrhea?

Answer 16

due to NSP4 that activates of the enteric nervous system (ENS)

Question 17

What happens when NSP4 activates the enteric nervous system?

Answer 17

tells the body to not absorb the fluids and dispel it more

Question 18

What are the 3 ways why the secretory diarrhea occurs due to rotaviral infections?

Answer 18

damage of tight-junction between cells, the NSP4 enterotoxin, destruction of enterocytes via lysis

Question 19

What causes damage to the tight junctions?

Answer 19

virus changes (increases) in the intracellular calcium levels = changes in the expression of tight junction proteins or ability to be on the cell surface to work= allows leakage and malabsorption

Question 20

What does the NSP4 enterotoxin also induce other than ENS responses?

Answer 20

CFTR mediated diarrhea

Question 21

How are rotaviral infections treated?

Answer 21

replacement of fluids (MOST EFFECTIVE TREATMENT)

Question 22

Is there a vaccine available to prevent rotaviral infections?

Answer 22

yes - oral vaccine via drops; highly effective in eliminating the disease

Question 23

What protein regulates the growth checkpoint?

Answer 23

Rb protein

Question 24

What does the Rb protein do?

Answer 24

bound to E2F (transcription factor) and holds it until it receives a signal telling it that the cell is ready for DNA replication

Question 25

What genes does E2F turn on when it is unbound from Rb?

Answer 25

the DNA replication genes to encode enzymes needed such as polymerases and ligases

Question 26

In order to phosphorylate Rb, what is needed upstream to tell it that it needs to be phosphorylated?

Answer 26

the RAS signaling pathway

Question 27

What does the RAS protein trigger?

Answer 27

a signaling pathway that will lead to the phosphorylation of Rb

Question 28

What triggers RAS?

Answer 28

growth factors that attaches to it cell surface receptor (kinase) that activates RAS

Question 29

What does the RAS signaling pathway also do other than phosphorylating Rb?

Answer 29

inactivates PKR by dephosphorylating it

Question 30

What activates PKR? What does it do once activated?

Answer 30

dsRNA = phosphorylates it to activate it | shuts down protein synthesis

Question 31

What occurs when PKR is inactivated?

Answer 31

protein translation moves forward

Question 32

Where do oncogenic mutations occur in >30% of human cancers? Generally in what protein/gene?

Answer 32

RAS Signaling pathway | mostly RAS itself

Question 33

What type of mutation does RAS have to cause cancer? What is the effect of this?

Answer 33

has a gain-of-function mutation | effect = it is always on despite if growth factors are present or not

Question 34

What is the status of PKR in cancer cells? What is the effect of this?

Answer 34

always inactivated due to RAS mutation = makes these cells more susceptible to dsRNA viruses

Question 35

What is the effect of infecting cancer cells with Reoviruses?

Answer 35

lyses cancer cells

Question 36

How are scientists using Reoviruses as an oncolytic agent?

Answer 36

engineering the Reovirus where it can only infect cancer cells (from any part of the body)

Question 37

If you treat a cancer patient with Reoviruses to target the cancer cells, what happens when the virus enters a non-tumor cell?

Answer 37

virus is immediately shut down because PKR is not inactivated by the RAS pathway

Question 38

Why can Reoviruses potentially be used as a treatment for cancer cells?

Answer 38

due to their preference for RAS-activated cells and their cytolytic ability

Question 39

Why do Reoviruses prefer RAS-activated cells even though they replicate their dsRNA genome in their double-layered capsid?

Answer 39

sometimes dsRNA leaks out into cytoplasm | since PKR is inactivated via RAS = no inhibition of protein translation = doesn’t matter if there was dsRNA present in the cytoplasm