Question 1

Which of the following best describes the principle behind herd immunity?

Accepted Answer

Immunity in most of the population prevents outbreaks by reducing the number of susceptible individuals.

Question 2

A patient receives a vaccine containing inactivated toxins from Clostridium tetani. What type of vaccine is this, and what is its main characteristic?

Accepted Answer

Toxoid vaccine; it induces immunity by exposing the immune system to inactivated toxins.

Question 3

Why are live attenuated vaccines generally more effective than inactivated vaccines?

Accepted Answer

They closely mimic a natural infection and induce both cellular and humoral immunity.

Question 4

Which of the following is a key advantage of monoclonal antibodies over conventional antibody preparations?

Accepted Answer

They are uniform, highly specific, and can be produced in large quantities.

Question 5

A new vaccine is developed using a genetically modified avirulent virus to deliver genes coding for antigens. What type of vaccine is this?

Accepted Answer

Recombinant vector vaccine

Question 6

Which of the following best explains why vaccination is often the only feasible way to control most viral diseases?

Accepted Answer

Viruses cannot be effectively treated with antibiotics, so prevention through vaccination is essential.

Question 7

A diagnostic test has a high probability of being reactive if the specimen is a true positive. What property does this describe?

Accepted Answer

Sensitivity

Question 8

Which of the following statements about adjuvants is correct?

Accepted Answer

Adjuvants are chemical additives that enhance the effectiveness of vaccines by improving the innate immune response.

Question 9

Which test would you use to detect antibodies against a pathogen in a patient's serum: direct or indirect ELISA?

Accepted Answer

Indirect ELISA

Question 10

A patient’s serum is mixed with a virus and red blood cells. No agglutination occurs. What does this indicate about the patient?

Accepted Answer

The patient has antibodies against the virus, which neutralize it and prevent hemagglutination.

Question 11

Which of the following best describes a conjugated vaccine?

Accepted Answer

A vaccine that combines polysaccharides with proteins to enhance immunogenicity, especially in children.

Question 12

What is the main difference between a precipitation reaction and an agglutination reaction?

Accepted Answer

Precipitation involves soluble antigens forming lattices with antibodies, while agglutination involves particulate antigens forming visible aggregates.

Question 13

Which of the following is a real-world example of a live attenuated vaccine?

Accepted Answer

Measles vaccine

Question 14

A laboratory is developing a new oral vaccine using plants as the source. What is a major advantage of this approach?

Accepted Answer

It avoids the use of animal hosts and may not require refrigeration.

Question 15

Which of the following best describes the function of a hybridoma in monoclonal antibody production?

Accepted Answer

A hybridoma is a fusion of a cancerous B cell and a normal antibody-producing B cell, producing monoclonal antibodies.

Question 16

Which of the following equations correctly represents the probability of a diagnostic test being reactive if the specimen is a true positive (sensitivity)?

Accepted Answer

$$ 	ext{Sensitivity} = \frac{	ext{True Positives}}{	ext{True Positives} + 	ext{False Negatives}} $$

Question 17

A patient is tested for HIV using a fluorescence-activated cell sorter (FACS). What is the main advantage of this technique?

Accepted Answer

It can separate and count cells based on size and fluorescence, allowing monitoring of immune cell populations.

Question 18

Which of the following best explains why the oral (Sabin) polio vaccine could sometimes cause polio, but the injected (Salk) vaccine does not?

Accepted Answer

The Sabin vaccine contains live attenuated virus, which can rarely revert to a virulent form, while the Salk vaccine contains inactivated virus.

Question 19

Which of the following is a characteristic of a nucleic acid (DNA) vaccine?

Accepted Answer

Injected naked DNA produces the protein antigen encoded in the DNA, stimulating both humoral and cellular immunity.

Practical Applications of Immunology: Vaccines and Diagnostic Immunology

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