Virus Quiz : Test your knowledge

1. Which of the following features helps distinguish viruses from bacteria in clinical practice?

1. Viruses can grow on routine nutrient agar; bacteria cannot.
2. Viruses require living cells for replication, whereas many bacteria can grow on artificial media.
3. Viruses have both DNA and RNA simultaneously; bacteria have only DNA.
4. Viruses are always larger than bacteria.

2. Which one of the following best describes “enveloped RNA virus” stability in the environment?

1. Generally less stable, often sensitive to detergents and drying.
2. Always more stable than non-enveloped DNA viruses.
3. Completely resistant to lipid solvents.
4. Stable for decades in open air without a host.

3. “Tissue culture” is preferred for isolation of many viruses because:

1. Viruses can multiply only in living cells, which tissue culture provides.
2. Viruses grow faster on tissue culture than on blood agar plates.
3. It eliminates the need for any biosafety precautions.
4. Viruses do not infect any animal models.

4. With reference to “viral shedding before symptom onset”, which of the following statements is/are correct?

1. It can make containment of respiratory viral outbreaks more difficult.
2. It implies that symptomatic case-based isolation alone may be insufficient.
3. It means that asymptomatic individuals can never transmit the virus.

Select the correct answer using the code below:

1. 1 only
2. 1 and 2 only
3. 2 and 3 only
4. 1, 2 and 3

5. In the SIR (Susceptible–Infectious–Recovered) model for viral spread, which of the following factors directly influences the transition from “Susceptible” to “Infectious”?

1. Contact rate between susceptible and infectious individuals.
2. Probability of transmission per contact.
3. Rate of recovery from infection.

Select the correct answer using the code below:

1. 1 and 2 only
2. 2 and 3 only
3. 1 and 3 only
4. 1, 2 and 3

6. Which of the following is a key reason why RNA viruses can adapt rapidly to antiviral drugs?

1. They possess perfect proofreading mechanisms.
2. They have high mutation rates due to error-prone polymerases.
3. They never recombine or reassort.
4. They lack any genetic material.

7. Which of the following is the main rationale behind “ring vaccination” strategy in viral disease control?

1. Vaccinate only the index case.
2. Vaccinate close contacts and contacts of contacts to form an immune buffer around cases.
3. Vaccinate entire countries simultaneously.
4. Vaccinate only individuals with prior infection.

8. With reference to “antigenic drift” and “antigenic shift” in influenza viruses, which of the following is/are correct?

1. Antigenic drift is due to gradual accumulation of point mutations.
2. Antigenic shift is due to reassortment of genome segments between different viral strains.
3. Both can have implications for vaccine effectiveness.

Select the correct answer using the code below:

1. 1 and 2 only
2. 1 and 3 only
3. 2 and 3 only
4. 1, 2 and 3

9. In a population where a new effective antiviral becomes widely available, which of the following outcomes is most likely if treatment is started early in infection?

1. Reduced duration of infectiousness and possibly reduced viral load.
2. Increase in the basic reproduction number (R₀).
3. Guaranteed eradication of the virus within one year.
4. No change in transmission dynamics.

10. For a viral infection where immunity wanes significantly over a few years, which public health approach is most appropriate to maintain population protection?

1. Single lifetime vaccination with no follow-up.
2. Periodic booster doses based on evidence of waning immunity.
3. Vaccination only during outbreaks with no scheduled doses.
4. Rely solely on natural infection for long-term protection.