Resistance, immunity, and vaccines

Question 1

Which form of immunity is used for prevention of viral infections? (humoral/ cell mediated)

Answer 1

Humoral

IgA is in secretions for local immunity

Question 2

What’s the first line of defense against viral infections in humoral immunity?

Answer 2

Immunity from secretory IgA

If it slips past then it can be stopped during plasma phase and IgG

Question 3

When is cell-mediated immunity needed for viral infections?

Answer 3

If there are no antibodies, or the virus gets INSIDE the cell

Question 4

Who do dendritic cells present viral parts to with class II MHC?

Answer 4

Th1 cells

Question 5

How are the killer cells activated?

Answer 5

Dendritic cells pick up debris and free virus, which are cross-presented on Class I to CTL which, with Th1 help, become activated killers.

Question 6

What is local immunity?

Answer 6

Protecting local site of invasion

secretory IgA is used

Question 7

Give an example of local immunity

Answer 7

Sabin (attenuated, live, oral) polio vaccine;

people immunized with it have high levels of IgA in their secretions and do not get colonized by the real virus

Question 8

Name 3 organisms against which cell-mediated immunity is most effective

Answer 8

Viruses

Intracellular bacteria: Mycobacteria, Listeria, and Brucella.
They get into macrophages and can survive there, but are killed if the macrophage can be activated by Th1 cells

Question 9

Identify those organisms against which humoral immunity is most effective

Answer 9

Bacteria that live extracellularly

Question 10

How does humoral immunity defend against bacteria?

Answer 10

Bacteria can be blocked from attachment to mucous membranes by IgA, and once in the body they are opsonized by plasma antibody and complement

Question 11

What is an adjuvant?

Answer 11

A substance that stimulate innate response

***Makes a greater response in vaccines that have them

Question 12

When should a kid get a diphtheria, pertussis, tetanus shot? (DTaP)

Answer 12

2 months, 3 months, and again at 4 months

Question 13

When should a kid get a measles, mumps, and rubella shot (MMR)?

Answer 13

12-15 months

Question 14

When should kids get a polio shot?

Answer 14

A dose at 2 months
A dose at 4 months
A dose at 6-18 months
A booster dose at 4-6 years

Question 15

How can you diagnose fetal infections?

Answer 15

IgM titers in child will show immune response to an infection in the baby

Question 16

What is a conjugate vaccine?

Answer 16

Carbohydrates coupled to an antigenic protein

Question 17

Which major immunogens are found in carbohydrate capsules

Answer 17

Hemophilus, Streptococcus, and Neisseria

Question 18

What cell responds to carbohydrate epitopes?

Answer 18

IgM

carbohydrates alone are T-independent

Question 19

Why are conjugate vaccines more effective?

Answer 19

1. IgM doesn’t get into tissues well, and create a good response.
2. So the carbohydrate is coupled to a protein ‘carrier’ to which Tfh cells could respond (tetanus or diphtheria toxoid, usually) and thus focus their help on the B cells responding to the attached carbohydrate.

Question 20

What is the name of the oral polio vaccine?

Answer 20

Sabin

Question 21

What are the characteristics of the oral polio vaccine?

Answer 21

attenuated, live

discontinued in U.S. because vaccine-associated polio

Question 22

What is the name of the parental polio vaccine?

Answer 22

Salk

Question 23

What are the characteristics of the parental polio vaccine?

Answer 23

killed, injected

Question 24

What is “herd immunity”?

Answer 24

The proportion of a given population that has immunity against a particular infection; it is commonly expressed as a percentage

Question 25

What is the herd effect?

Answer 25

Herd effect is the decrease in infection rate in the non-immune part of the herd, as a consequence of herd immunity.

Question 26

Will a high infectivity or low infectivity require high herd immunity?

Answer 26

diseases with a high infectivity, like measles, require high herd immunity (about 95%) to achieve a herd effect. Less infectious diseases require a proportionately lower herd immunity.