Question 1

Which of the following best explains why the introduction of vaccines led to a dramatic decrease in the incidence of polio and measles, as shown in the provided epidemiological graphs?

Accepted Answer

Vaccines stimulate the immune system to develop adaptive immunity, reducing the number of susceptible hosts.

Question 2

Which of the following is a key advantage of attenuated (live) vaccines, as depicted in the diagram showing their interaction with the immune system?

Accepted Answer

They stimulate both humoral and cell-mediated immune responses, often resulting in lifelong immunity.

Question 3

A patient with an egg allergy should avoid certain vaccines. Based on vaccine production methods, which type of vaccine is most likely to pose a risk to this patient?

Accepted Answer

Vaccines cultured in chicken eggs, such as some influenza vaccines.

Question 4

Which of the following best describes the principle behind the ELISA (enzyme-linked immunosorbent assay) test?

Accepted Answer

It uses an enzyme-linked antibody that produces a colored product when it reacts with its substrate, indicating the presence of antigen or antibody.

Question 5

A newborn tests positive for HIV antibodies using an ELISA, but six months later, the test is negative. What is the most likely explanation?

Accepted Answer

The initial antibodies detected were passively acquired maternal antibodies, which degraded over time.

Question 6

Which of the following serological tests is most appropriate for quantifying the amount of antibody in a patient's serum?

Accepted Answer

Agglutination titration

Question 7

Which of the following statements about passive immunotherapy is correct?

Accepted Answer

It provides immediate protection but does not result in long-term immunity.

Question 8

Which of the following best distinguishes agglutination from precipitation reactions in serological testing?

Accepted Answer

Agglutination involves the clumping of insoluble particles, while precipitation involves the aggregation of soluble molecules.

Question 9

A laboratory is using a Western blot (immunoblot) to confirm the presence of antibodies against HIV in a patient's serum. Which step is unique to this technique compared to other serological tests?

Accepted Answer

Separation of proteins by electrophoresis before antibody detection.

Question 10

Which of the following is a disadvantage of attenuated (live) vaccines?

Accepted Answer

They may cause disease in immunocompromised individuals due to residual virulence.

Question 11

Which of the following best explains why combination vaccines are advantageous in immunization programs?

Accepted Answer

They allow simultaneous administration of antigens from several pathogens, reducing the number of injections needed.

Question 12

Which of the following is a limitation of using antisera for passive immunotherapy?

Accepted Answer

Antibodies in antisera are degraded quickly and do not provide long-term protection.

Question 13

Which of the following best describes the function of adjuvants in inactivated (killed) vaccines?

Accepted Answer

They increase the effective antigenicity of the vaccine, enhancing the immune response.

Question 14

A patient’s serum is serially diluted and tested for agglutination with a specific antigen. The highest dilution that still shows agglutination is 1:1000. What is the antibody titer?

Accepted Answer

$$1:1000$$

Question 15

Which of the following is a key feature of the antibody sandwich ELISA?

Accepted Answer

The antigen is 'sandwiched' between two antibody molecules, allowing for sensitive detection of antigen.

Question 16

Which of the following serological tests would be most appropriate for rapid, point-of-care diagnosis of a pregnancy or certain infections?

Accepted Answer

Immunochromatography assay (dipstick test)

Question 17

Which of the following statements about toxoid vaccines is correct?

Accepted Answer

They are chemically or thermally modified toxins that stimulate antibody-mediated immunity.

Question 18

Which of the following best describes the principle of the viral neutralization test?

Accepted Answer

Antibodies in the serum neutralize the virus, preventing cytopathic effects in cell culture.

Question 19

Which of the following is a reason why parents should continue to vaccinate their children even when the incidence of vaccine-preventable diseases is low?

Accepted Answer

Maintaining high vaccination rates prevents outbreaks by sustaining herd immunity.

Immunization and Immune Testing: Principles and Applications

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