Cultivation of viruses MCQs With Answer offers B.Pharm students a focused, keyword-rich overview of virus cultivation techniques, assays, and biosafety essentials. This guide covers cell culture systems, embryonated eggs, animal models, plaque assays, TCID50, viral titration, and practical considerations for antiviral testing and contamination control. Questions emphasize experimental design, interpretation of cytopathic effects, one-step and multi-step growth curves, multiplicity of infection (MOI), and advanced methods like organoids and baculovirus expression. Perfect for exam prep and laboratory competence, these MCQs strengthen understanding of virology practicals and quality control in pharmaceutical research. Now let’s test your knowledge with 50 MCQs on this topic.
Q1. Which system is most commonly used for large-scale propagation of influenza viruses for vaccine production?
- Vero cell culture
- Primary human fibroblasts
- Embryonated hen eggs
- HeLa cell line
Correct Answer: Embryonated hen eggs
Q2. What does PFU stand for in viral quantification?
- Particle Formation Units
- Plaque Forming Units
- Protein Functional Units
- Pathogen Frequency Units
Correct Answer: Plaque Forming Units
Q3. Which assay measures the dilution of virus that infects 50% of cell cultures?
- Hemagglutination assay
- TCID50 assay
- Pseudotype neutralization
- ELISA
Correct Answer: TCID50 assay
Q4. Which cell line is commonly used to propagate poliovirus and other enteroviruses?
- MDCK
- Vero
- HeLa
- BHK-21
Correct Answer: HeLa
Q5. What is the primary advantage of using continuous cell lines over primary cells?
- Higher physiological similarity to tissues
- Unlimited lifespan and ease of maintenance
- Lower risk of contamination
- More ethical concerns
Correct Answer: Unlimited lifespan and ease of maintenance
Q6. Which method separates viruses based on buoyant density?
- PCR amplification
- Sucrose gradient centrifugation
- Hemadsorption
- Immunofluorescence
Correct Answer: Sucrose gradient centrifugation
Q7. Cytopathic effect (CPE) refers to:
- Virus-induced visible changes in host cells
- Formation of viral plaques on agar
- Neutralization of virus by antibodies
- Inactivation of complement proteins
Correct Answer: Virus-induced visible changes in host cells
Q8. One-step growth curve is used to study which feature of virus replication?
- Multiple cycles of infection over days
- Single synchronous replication cycle and eclipse phase
- Host immune response kinetics
- Viral mutation rates
Correct Answer: Single synchronous replication cycle and eclipse phase
Q9. Which of the following is a permissive cell line for rabies virus propagation?
- MDCK cells
- Neuroblastoma (N2a) cells
- CHO cells
- 293T cells
Correct Answer: Neuroblastoma (N2a) cells
Q10. Hemagglutination assay detects viruses by their ability to:
- Cause cell lysis
- Bind and agglutinate red blood cells
- Generate plaques on agar
- Induce fluorescence
Correct Answer: Bind and agglutinate red blood cells
Q11. What is multiplicity of infection (MOI)?
- Number of plaques per mL
- Ratio of infectious virions to target cells during infection
- Time required for viral adsorption
- Amount of antibody needed for neutralization
Correct Answer: Ratio of infectious virions to target cells during infection
Q12. Which biosafety level is typically required for handling poliovirus in laboratory culture?
- BSL-1
- BSL-2
- BSL-3
- BSL-4
Correct Answer: BSL-2
Q13. Which technique is used to quantify viral RNA in a sample?
- Western blot
- Real-time RT-PCR
- Hemagglutination assay
- Neutralization test
Correct Answer: Real-time RT-PCR
Q14. Which of the following enhances influenza virus infectivity in cell culture by cleaving HA?
- Trypsin
- Papain
- DNase
- Proteinase K
Correct Answer: Trypsin
Q15. Plaque purification is performed to:
- Measure antibody titers
- Isolate a clonal viral population
- Lyse host cells for protein analysis
- Determine viral genome sequence
Correct Answer: Isolate a clonal viral population
Q16. Syncytium formation is characteristic of infection by which type of virus?
- Non-enveloped enteroviruses
- Enveloped paramyxoviruses
- DNA bacteriophages
- Retrovirus integrases
Correct Answer: Enveloped paramyxoviruses
Q17. Which insect cell line is commonly used with baculovirus expression systems?
- HeLa
- Sf9
- CHO
- Vero
Correct Answer: Sf9
Q18. TCID50 differs from PFU because TCID50 measures:
- Direct count of viral particles
- Infectious dose causing cytopathic effect in 50% wells
- Hemagglutinin units
- Antibody neutralization strength
Correct Answer: Infectious dose causing cytopathic effect in 50% wells
Q19. Which medium supplement helps prevent fungal contamination in long-term cell culture?
- Penicillin only
- Streptomycin only
- Amphotericin B (antifungal)
- Trypsin
Correct Answer: Amphotericin B (antifungal)
Q20. Envelope viruses are generally more sensitive to which condition compared to non-enveloped viruses?
- Detergents and organic solvents
- UV radiation
- High temperatures
- Low pH in stomach
Correct Answer: Detergents and organic solvents
Q21. Which assay is used to measure neutralizing antibodies against a virus?
- Plaque reduction neutralization test (PRNT)
- Hemagglutination inhibition assay
- Western blot
- Direct fluorescent antibody staining
Correct Answer: Plaque reduction neutralization test (PRNT)
Q22. Which cell culture condition promotes viral adsorption to host cells?
- Rapid shaking of culture
- Centrifugal enhancement or spinoculation
- Complete absence of serum
- High antibiotic concentrations
Correct Answer: Centrifugal enhancement or spinoculation
Q23. The eclipse phase in a one-step growth curve is characterized by:
- Peak extracellular virus titers
- Loss of detectable infectious intracellular virions after entry
- Initial increase in plaque numbers
- Onset of cytopathic effect
Correct Answer: Loss of detectable infectious intracellular virions after entry
Q24. Which of the following is a continuous cell line derived from African green monkey kidney?
- BHK-21
- Vero
- HEK293
- MRC-5
Correct Answer: Vero
Q25. Reverse genetics systems in virology are primarily used to:
- Purify viral particles
- Generate infectious virus from cloned cDNA
- Measure antibody titers
- Detect viral RNA by PCR
Correct Answer: Generate infectious virus from cloned cDNA
Q26. Use of fetal bovine serum (FBS) in media primarily provides:
- Antiviral agents
- Growth factors and attachment factors
- Selective antibiotics
- Viral neutralizing antibodies
Correct Answer: Growth factors and attachment factors
Q27. In plaque assays, agar overlay serves to:
- Provide nutrients for virus
- Restrict viral spread to neighboring cells to form plaques
- Enhance antibody binding
- Stain infected cells
Correct Answer: Restrict viral spread to neighboring cells to form plaques
Q28. Which parameter is essential when choosing a cell line for viral isolation?
- Cost of culture media alone
- Permissiveness and susceptibility of the cell to the virus
- Origin of the researcher
- Color of the culture flask
Correct Answer: Permissiveness and susceptibility of the cell to the virus
Q29. Focus forming assays differ from plaque assays by detecting:
- Only lytic viruses
- Infected cell foci using immunostaining rather than visible plaques
- Viral RNA copies
- Hemagglutination units
Correct Answer: Infected cell foci using immunostaining rather than visible plaques
Q30. Which step immediately follows viral adsorption in the replication cycle?
- Assembly of virions
- Penetration and entry into the host cell
- Release by budding
- Genome integration into host DNA
Correct Answer: Penetration and entry into the host cell
Q31. Which assay is rapid and measures total viral particles by light scattering, not infectivity?
- Electron microscopy particle count
- Plaque assay
- TCID50
- Hemagglutination inhibition
Correct Answer: Electron microscopy particle count
Q32. An advantage of organoid cultures for virus study is:
- Lower cost than cell lines
- Better mimicry of in vivo tissue architecture and function
- No need for biosafety precautions
- Unlimited reproducibility without variability
Correct Answer: Better mimicry of in vivo tissue architecture and function
Q33. Which reagent is commonly used to detach adherent mammalian cells for subculture?
- Formaldehyde
- Trypsin-EDTA
- Amphotericin B
- Polyethylene glycol
Correct Answer: Trypsin-EDTA
Q34. Viral adsorption efficiency can be increased by lowering which temperature during inoculation?
- 4°C to promote endocytosis
- Room temperature to freeze cells
- 37°C for rapid internalization, often shortened to favor binding at 4°C
- 100°C to denature surface proteins
Correct Answer: 37°C for rapid internalization, often shortened to favor binding at 4°C
Q35. Which of the following indicates contamination by mycoplasma in cell cultures?
- Visible fungal hyphae under microscope
- Slow cell growth with altered morphology and failure to show turbidity
- Immediate cell lysis within minutes
- Formation of bacterial colonies on agar only
Correct Answer: Slow cell growth with altered morphology and failure to show turbidity
Q36. Neutral red uptake assay in virus research is used to assess:
- Viral genome sequences
- Cell viability and cytotoxicity post-infection
- Hemagglutination titers
- Antibody specificity
Correct Answer: Cell viability and cytotoxicity post-infection
Q37. Which viral quantification uses antibodies to detect infected cells forming foci?
- Plaque assay
- Focus forming assay (immunostaining)
- TCID50 only
- Electron microscopy
Correct Answer: Focus forming assay (immunostaining)
Q38. Which practice reduces risk of cross-contamination between viral stocks?
- Using same pipette tips for all samples
- Aliquoting stocks and working in biosafety cabinet with sterile technique
- Keeping all stocks at room temperature
- Sharing cell culture flasks between viruses
Correct Answer: Aliquoting stocks and working in biosafety cabinet with sterile technique
Q39. Which of these viruses is typically grown in MDCK cell lines for research and vaccine assays?
- Hepatitis B virus
- Influenza virus
- HIV
- Poliovirus
Correct Answer: Influenza virus
Q40. Gradient ultracentrifugation separates viral particles primarily by:
- Molecular weight of nucleic acids
- Buoyant density of particles
- Antigenic properties
- Color of viral capsid
Correct Answer: Buoyant density of particles
Q41. Which cell culture contaminant is smallest and lacks a cell wall, often detected by PCR?
- Bacteria with spores
- Fungi
- Mycoplasma
- Protozoa
Correct Answer: Mycoplasma
Q42. In antiviral drug testing, EC50 refers to:
- Concentration causing 50% cell death
- Concentration of drug that reduces viral replication by 50%
- 50% effective plasma concentration in humans
- Enzymatic cleavage at 50°C
Correct Answer: Concentration of drug that reduces viral replication by 50%
Q43. What is multiplicity reactivation in virology?
- Reactivation of latent viruses by heat
- Repair and recombination between damaged viral genomes co-infecting a cell
- Measurement of MOI by plaque assay
- Activation of complement pathways
Correct Answer: Repair and recombination between damaged viral genomes co-infecting a cell
Q44. Which assay is most appropriate to determine infectivity loss after heat inactivation?
- Plaque assay to measure remaining infectious units
- Western blot for capsid proteins
- qPCR to measure genome copies only
- Hemagglutination unit measurement
Correct Answer: Plaque assay to measure remaining infectious units
Q45. Which viral property is best assessed by single-step versus multi-step growth experiments?
- Genomic sequence variation
- Replication kinetics at high versus low MOI
- Antibody binding affinity
- Capsid thermal stability
Correct Answer: Replication kinetics at high versus low MOI
Q46. Which cell line is frequently used for production of recombinant proteins and viral vectors and is of human embryonic kidney origin?
- CHO
- HEK293
- Vero
- MDCK
Correct Answer: HEK293
Q47. Which detection method identifies viral proteins in infected cells using labeled antibodies?
- RT-PCR
- Immunofluorescence assay (IFA)
- Hemagglutination assay
- Plaque assay
Correct Answer: Immunofluorescence assay (IFA)
Q48. During plaque assay, which overlay alternative allows diffusion of neutralizing antibodies for certain assays?
- Hard plastic overlay
- Agarose or methylcellulose overlay
- Oil overlay
- Solid glass overlay
Correct Answer: Agarose or methylcellulose overlay
Q49. Which factor most influences the host range of a virus in culture?
- Presence of suitable cell surface receptors and intracellular factors
- Color of growth medium
- Brand of incubator
- Type of plasticware used only
Correct Answer: Presence of suitable cell surface receptors and intracellular factors
Q50. Reporter viruses engineered to express GFP are useful because they:
- Require special electron microscopy
- Allow real-time visualization of infection and quantification without staining
- Are always non-infectious
- Eliminate the need for biosafety containment
Correct Answer: Allow real-time visualization of infection and quantification without staining
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