Question 1

Which of the following best describes the principle of herd immunity, and how is the herd immunity threshold (HIT) calculated for a given infectious disease?

Accepted Answer

Herd immunity occurs when a sufficient proportion of the population is immune, reducing disease transmission. HIT is calculated as $$p = 1 - \frac{1}{R_0$}.$$

Question 2

A patient receives antibodies against a snake venom after being bitten. Which type of immunity is this, and is it naturally or artificially acquired?

Accepted Answer

Artificially acquired passive immunity

Question 3

Which of the following vaccine types is most likely to require refrigeration and carries a risk of causing disease in immunocompromised individuals?

Accepted Answer

Live attenuated vaccine

Question 4

A new vaccine is developed using mRNA that encodes a viral spike protein. Which of the following best describes the mechanism of this vaccine?

Accepted Answer

The mRNA is translated into protein by the host cell, which then triggers an immune response.

Question 5

Which diagnostic method involves the use of a capture antibody, a detection antibody, and a substrate to produce a measurable signal?

Accepted Answer

Sandwich ELISA

Question 6

A patient’s serum is serially diluted and mixed with a virus before being added to cultured cells. Fewer plaques are observed compared to the control. What does this indicate?

Accepted Answer

The patient has neutralizing antibodies against the virus.

Question 7

Which of the following is a major advantage of inactivated vaccines compared to live attenuated vaccines?

Accepted Answer

They are safe for immunocompromised patients and stable at room temperature.

Question 8

Which of the following best explains why the MMR vaccine controversy led to outbreaks of measles and pertussis in the US and UK?

Accepted Answer

A fraudulent study led to decreased vaccination rates, reducing herd immunity.

Question 9

Which of the following best describes the function of adjuvants in subunit vaccines?

Accepted Answer

They stimulate cytokine release and enhance antigen uptake by dendritic cells.

Question 10

A gene-editing tool uses a guide RNA to locate a specific DNA sequence and an enzyme to cut both DNA strands, allowing insertion of a new sequence. What is this tool called?

Accepted Answer

CRISPR-Cas9

Question 11

A patient with leukemia and HIV receives a bone marrow transplant from a donor with two copies of the CCR5-Δ32 allele. What is the most likely outcome regarding HIV infection?

Accepted Answer

The patient’s cells will lack CCR5 receptors, preventing HIV entry and reducing viral levels below detection.

Question 12

Which of the following best describes the difference between direct and sandwich ELISA?

Accepted Answer

Direct ELISA detects antigen with a labeled antibody, while sandwich ELISA uses a capture and detection antibody to 'sandwich' the antigen.

Question 13

Which of the following is a key feature of recombinant vector vaccines?

Accepted Answer

They use a genetically modified carrier virus to deliver genetic information from the pathogen.

Question 14

Which laboratory technique is used to amplify a specific DNA sequence exponentially and is essential for genetic diagnostics?

Accepted Answer

Polymerase chain reaction (PCR)

Question 15

Reverse transcription PCR (RT-PCR) is particularly useful for detecting which type of pathogen genetic material?

Accepted Answer

RNA

Question 16

Which of the following best explains why booster shots are often required for inactivated vaccines?

Accepted Answer

Inactivated vaccines induce a weaker immune response and do not stimulate long-lived memory cells as effectively as live attenuated vaccines.

Question 17

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

Accepted Answer

Haemophilus influenzae type B (Hib) vaccine

Question 18

Which of the following best describes the main goal of immunological diagnostic tests such as ELISA and agglutination reactions?

Accepted Answer

To detect the presence of specific antigens or antibodies in patient samples

Question 19

A patient’s blood sample is tested for the presence of anti-B antibodies using an agglutination reaction. Agglutination is observed. What does this indicate about the patient’s blood type?

Accepted Answer

The patient has type A blood.

Biomedical Applications: Vaccines, Diagnostics, Therapeutics, and Molecular Methods

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