lecture 2 part 2

Question 1

name the 4 most common viral diseases

Answer 1

common cold
influenza
flulike syndromes
gastroenteritis (stomach bug – diarrhea and vomiting)

Question 2

name six DETERMINANTS of viral disease (affect how virulent a virus is)

Answer 2

-exposure/ entry – very virulent if enters through respiratory

-viral dose: higher = greater chance of infection

-target tissue/tissue tropism – if it has to move to a secondary site, there’s more time to deal with it

-permissiveness of cells

-host status (age, immunity, health)

-viral structure - naked vs enveloped. in gut, naked virus has a better chance of surviving

Question 3

explain the pathway of the POLIO VIRUS

Answer 3

virus is ingested and goes through GALT. the virus invades via M cells and replicates in monocytes.

the virus then gets to a regional lymph node and replicates there.

from the lymph node, it goes into the blood (viremia) and crosses the endothelium of the BLOOD BRAIN BARRIER.
it goes into the spinal cord and replicates there, causing cell destruction and paralysis

then the virus is excreted in the feces through the gut

Question 4

what is the primary site of infection for the polio virus

Answer 4

the gut

Question 5

what are the 3 classes of viral vaccines?

Answer 5

1. killed
2. live attenuated
3. subunit

Question 6

differentiate between the 3 types of viral viruses

Answer 6

killed – killed virus

attenuated – have mutations (has to be more than one). they are whole viruses that look normal from the outside but are incapable of sustaining an infection

subunit based – subunit of a viral protein is introduced. it is not functional unless it has the other subunits

Question 7

which is considered the “best” type of viral vaccine and why

Answer 7

attenuated viruses look normal they just have mutations that make it incapable of sustaining an infection

attenuated viruses induce an antibody AND a T cell response

subunit and killed viral vaccines only induce an antibody response

Question 8

which specific viral vaccines are subunit based?

Answer 8

hepatitis B
COVID

Question 9

measles, mumps, and rubella are which type of viral vaccine?

Answer 9

live attenuated

Question 10

besides measles, mumps, and rubella, name more vaccines that are live attenuated

Answer 10

polio, rotavirus, yellow fever, chicken virus, shingles

Question 11

name 3 specific viral vaccines that are KILLED

Answer 11

hepatitis A, rabies, influenza

Question 12

explain 5 ways in which viruses attempt to evade the immune system

Answer 12

-produce proteins that inhibit the IFN response

-modify viral antigen to make them look like friendly host proteins

-cell-cell spreading (synctia)

-suppress antigen presentation (interfere with binding of peptide to MHC class 1)

-inhibit lymphocytes(T cells, B cells, NK cells)

Question 13

what is the BEST viral immunosuppressor

Answer 13

HIV — interferes with the helper T cells

Question 14

which 2 viruses have a MODERATE degree of immunosuppression

Answer 14

measles and rubella

Question 15

which 2 viruses have a low degree of immunosuppression

Answer 15

HSV, Vaccinia

Question 16

explain how HSV and Vaccinia exhibit ___ immunosuppression

Answer 16

LOW immunosuppression

produce proteins that function as viroreceptors or VIROKINES – compete with the cytokines of the host organism

Question 17

which virus exhibits immunosuppression by causing the overproduction of cytokines?

Answer 17

measles – moderate response

Question 18

true or false

the immune system itself is a MAJOR contributor to disease or symptoms caused by some viral infection

Answer 18

true:

ex:

-experiencing flu like symptoms is the effect of the PRODROME phase of the immune system – due to the innate response. cytokines cause the hypothalamus to raise the temperature

type IV hypersensitivity reactions –allergic reaction. mediated by effector T cells

Type III hypersensitivity reactions: IgG antibody-antigen deposits form in small vessels and alveoli. aggregate there and clog the vessels

Question 19

type 3 and type 4 hypersensitivity reactions are caused by….

Answer 19

VIRUSES

Question 20

Explain how the hepatitis B virus exhibits immunopathologies

Answer 20

causes hypersensitivity response

CD8+ T cell – causes type IV hypersensitivity
Antibody – causes type 3 hypersensitivity

Question 21

Which TWO viruses induce both type 3 and type 4 hypersensitivity reactions? what is the term for this?

Answer 21

hepatitis B and RSV
called immunopathologies

Question 22

a “cytokine storm” can cause…

Answer 22

septic shock
ARDS – acute respiratory distress syndrome

Question 23

name 4 symptoms of ARDS and the cause of it

Answer 23

cause = cytokine storm. too many pathways lead to the production of cytokines which is not good for the cell

symptoms:
necrosis (death of cells due to lack of blood supply)
tissue destruction
influx of leukocytes (white blood cells)
dilation of blood vessels

Question 24

what will happen in the prodrome phase is very long?

Answer 24

the virus will continually replicate at the primary site. eventually they will accumulate and be released to the secondary site of infection – bad symptoms will be experiencede

Question 25

explain the disease course of a virus when the prodrome phase is short

Answer 25

prodrome phase lasting ~1 day – symptoms will be experienced at the primary site of infection, and then there will be healing after around 4 days