Genetically engineered vaccines MCQs With Answer
This quiz set is designed for M.Pharm students specializing in Immunotechnology to reinforce advanced concepts in genetically engineered vaccines. It covers principles of recombinant antigen design, expression systems, viral and non-viral vectors, VLPs, DNA and mRNA platforms, adjuvant considerations, quality control, and regulatory/safety aspects. Questions emphasize molecular strategies such as codon optimization, glycosylation impacts, epitope mapping, reverse vaccinology, and cold-chain stability challenges. Use these MCQs to test critical thinking about vaccine development pipelines, production hurdles and immunological outcomes, helping you prepare for exams and practical decision-making in vaccine research, formulation, and regulatory assessment.
Q1. Which of the following best describes a genetically engineered subunit vaccine?
- A vaccine composed of whole inactivated pathogens produced by classical attenuation
- A vaccine containing isolated polysaccharide antigens chemically conjugated to carrier proteins
- A vaccine containing one or more recombinant antigenic proteins expressed in a host expression system
- A live viral vaccine with random mutations introduced by serial passage
Correct Answer: A vaccine containing one or more recombinant antigenic proteins expressed in a host expression system
Q2. Which expression system is preferred when correct eukaryotic glycosylation of a recombinant antigen is essential for immunogenicity?
- Escherichia coli
- Yeast (Saccharomyces cerevisiae or Pichia pastoris)
- Insect cells using baculovirus expression
- Cell-free bacterial lysate systems
Correct Answer: Insect cells using baculovirus expression
Q3. What is the primary advantage of virus-like particles (VLPs) in vaccine design?
- They replicate mildly in the host producing sustained antigen expression
- They present repetitive antigenic epitopes in native conformation without containing viral genome
- They require live adjuvants to generate immune response
- They are simple peptides that do not require folding or post-translational modification
Correct Answer: They present repetitive antigenic epitopes in native conformation without containing viral genome
Q4. Which of the following is the primary immunological advantage of mRNA vaccines over traditional subunit vaccines?
- They induce only humoral responses and no cellular immunity
- They enter the nucleus and integrate into host DNA for long-term expression
- They enable in situ antigen synthesis leading to both MHC class I and class II presentation
- They require live-attenuated viral backbones for delivery
Correct Answer: They enable in situ antigen synthesis leading to both MHC class I and class II presentation
Q5. Codon optimization in recombinant vaccine antigen design primarily aims to:
- Change antigenic epitopes to avoid immune recognition
- Increase translation efficiency in the chosen host expression system
- Introduce glycosylation sites not present in native protein
- Reduce antigen molecular weight for easier purification
Correct Answer: Increase translation efficiency in the chosen host expression system
Q6. Which viral vector is non-replicating in humans and commonly used for delivering genetically engineered vaccine antigens?
- Adeno-associated virus (AAV) that replicates robustly in human cells
- Replication-competent vesicular stomatitis virus (VSV)
- Non-replicating adenoviral vectors (e.g., Ad5-based vectors with E1 deletion)
- Live attenuated measles virus wild-type strain
Correct Answer: Non-replicating adenoviral vectors (e.g., Ad5-based vectors with E1 deletion)
Q7. In designing a recombinant protein vaccine, which post-translational modification is most likely to affect antigenicity and receptor binding?
- Phosphorylation of internal residues not exposed on surface
- N-linked glycosylation of surface-exposed asparagine residues
- Peptide bond formation during translation
- Signal peptide cleavage in the cytosol that never reaches secretory pathway
Correct Answer: N-linked glycosylation of surface-exposed asparagine residues
Q8. The DIVA (Differentiating Infected from Vaccinated Animals) strategy in genetically engineered vaccines typically involves:
- Using whole killed pathogens to produce broad antibody profiles
- Incorporating marker genes or excluding non-essential antigens so diagnostics can distinguish infection from vaccination
- Administering higher antigen doses to mask natural infection
- Using live wild-type pathogens at subclinical doses
Correct Answer: Incorporating marker genes or excluding non-essential antigens so diagnostics can distinguish infection from vaccination
Q9. Reverse vaccinology contributes to genetically engineered vaccine development by:
- Using classical culture methods to inactivate pathogens
- Sequencing the pathogen genome to identify candidate antigens computationally
- Randomly mutating genes to observe immunogenic outcomes
- Employing live animal infection models exclusively for antigen selection
Correct Answer: Sequencing the pathogen genome to identify candidate antigens computationally
Q10. Which assay is most appropriate to measure functional neutralizing antibodies elicited by a recombinant viral surface protein vaccine?
- ELISA measuring total IgG against the antigen without assessing function
- Complement fixation test only
- Virus neutralization assay (plaque reduction neutralization test or pseudovirus neutralization)
- Western blot detecting antigen-binding proteins
Correct Answer: Virus neutralization assay (plaque reduction neutralization test or pseudovirus neutralization)
Q11. Which purification challenge is particularly critical when expressing recombinant antigens in E. coli for vaccines?
- Removal of endotoxin (lipopolysaccharide) to acceptable levels
- Ensuring human-like N-glycosylation patterns are maintained
- Separating antigens from host-derived viral particles
- Preventing recombination with host nuclear DNA
Correct Answer: Removal of endotoxin (lipopolysaccharide) to acceptable levels
Q12. Prime-boost vaccine strategies for genetically engineered vaccines are used to:
- Reduce immune response by repeated low-dose antigen
- Enhance magnitude and quality of immune responses by combining different platforms (e.g., DNA prime, viral vector or protein boost)
- Ensure only mucosal immunity is generated
- Replace need for adjuvants entirely
Correct Answer: Enhance magnitude and quality of immune responses by combining different platforms (e.g., DNA prime, viral vector or protein boost)
Q13. Structural vaccinology helps antigen design by:
- Using electron microscopy and crystallography to map neutralizing epitopes and stabilize antigen conformation
- Relying solely on peptide arrays without 3D structural information
- Promoting random peptide libraries without structural constraints
- Focusing only on adjuvant selection rather than antigen structure
Correct Answer: Using electron microscopy and crystallography to map neutralizing epitopes and stabilize antigen conformation
Q14. Which adjuvant characteristic is most desirable for genetically engineered protein vaccines aimed at eliciting a strong Th1 cellular response?
- Purely depot-forming oily formulation that only enhances humoral response
- Tendency to strongly activate TLRs (e.g., TLR4 or TLR9 agonists) to promote cellular immunity
- Complete absence of innate immune stimulation to avoid reactogenicity
- Adjuvants that selectively inhibit antigen-presenting cells
Correct Answer: Tendency to strongly activate TLRs (e.g., TLR4 or TLR9 agonists) to promote cellular immunity
Q15. A major regulatory concern specific to viral-vectored genetically engineered vaccines is:
- Ensuring absence of residual bacterial endotoxin only
- Assessing risk of vector genome recombination, shedding, and pre-existing anti-vector immunity
- Guaranteeing irreversible genomic integration in host cells
- Validation of chemical inactivation methods used for whole-cell vaccines
Correct Answer: Assessing risk of vector genome recombination, shedding, and pre-existing anti-vector immunity
Q16. Which modification can improve thermostability of a recombinant protein vaccine for easier cold-chain management?
- Removing disulfide bonds to increase flexibility
- Lyophilization with stabilizers (e.g., sugars, amino acids) and formulation optimization to reduce aggregation
- Increasing free water content in liquid formulation
- Increasing ionic strength to destabilize tertiary structure
Correct Answer: Lyophilization with stabilizers (e.g., sugars, amino acids) and formulation optimization to reduce aggregation
Q17. When designing epitope-based genetically engineered vaccines, which factor is essential to ensure broad population coverage?
- Selecting epitopes restricted to a single HLA allele common only in one ethnic group
- Including multiple conserved T-cell epitopes across diverse HLA haplotypes and covering B-cell neutralizing epitopes
- Designing epitopes that are highly variable and subject to antigenic drift
- Avoiding conserved regions to minimize cross-reactivity
Correct Answer: Including multiple conserved T-cell epitopes across diverse HLA haplotypes and covering B-cell neutralizing epitopes
Q18. In the context of DNA vaccines, which delivery method increases cellular uptake and expression of plasmid DNA in muscle tissue?
- Intravenous injection of naked plasmid without adjuvant
- Electroporation at the injection site to transiently permeabilize cell membranes
- Topical application on intact skin without penetration enhancers
- Oral delivery without protection from gastric degradation
Correct Answer: Electroporation at the injection site to transiently permeabilize cell membranes
Q19. A genetically engineered vaccine designed against a rapidly mutating virus should ideally target:
- Highly variable surface loops only
- Conserved neutralizing epitopes less prone to antigenic drift, possibly combined with broad T-cell epitopes
- Only non-structural proteins that never elicit immune responses
- Host proteins to induce autoimmunity that blocks infection
Correct Answer: Conserved neutralizing epitopes less prone to antigenic drift, possibly combined with broad T-cell epitopes
Q20. During scale-up manufacture of a recombinant vaccine protein, which parameter is most critical to ensure product consistency between batches?
- Only the color of the final bulk solution
- Controlled upstream parameters (host cell line, culture conditions), consistent downstream purification and validated potency assays
- Random variation of fermentation temperature to test robustness
- Changing expression vectors frequently for diversity
Correct Answer: Controlled upstream parameters (host cell line, culture conditions), consistent downstream purification and validated potency assays
