Introduction
Synthetic peptide vaccines MCQs With Answer is a focused quiz resource tailored for M. Pharm students studying Immunotechnology. This collection clarifies key concepts such as epitope selection, peptide synthesis and purification, adjuvant selection, carrier conjugation, immune processing (MHC presentation and cross‑presentation), and modern delivery systems. Questions probe deeper issues like HLA polymorphism, multi‑epitope design strategies, stability improvements using non‑natural amino acids, and quality control assays required for regulatory approval. Each MCQ is designed to reinforce theoretical understanding and practical considerations encountered during peptide vaccine development, formulation, and preclinical immunogenicity testing.
Q1. What best defines a synthetic peptide vaccine?
- A vaccine composed of chemically synthesized short peptides representing defined B‑ or T‑cell epitopes intended to induce specific immune responses
- A whole‑inactivated viral vaccine produced by chemical inactivation
- A DNA plasmid encoding a full‑length antigen for in vivo expression
- A live attenuated microorganism formulated with adjuvant
Correct Answer: A vaccine composed of chemically synthesized short peptides representing defined B‑ or T‑cell epitopes intended to induce specific immune responses
Q2. What is the typical length of peptides that bind to MHC class I molecules?
- 3–5 amino acids
- 8–10 amino acids
- 20–25 amino acids
- 30–40 amino acids
Correct Answer: 8–10 amino acids
Q3. Which peptide length range most commonly binds to MHC class II molecules?
- 5–8 amino acids
- 8–10 amino acids
- 12–25 amino acids
- 30–50 amino acids
Correct Answer: 12–25 amino acids
Q4. Which is the principal advantage of synthetic peptide vaccines compared with whole‑protein or live vaccines?
- Ability to replicate in host cells for long‑term antigen presentation
- Defined composition with minimized risk of infection and tailored epitope specificity
- Guaranteed induction of broadly neutralizing antibodies across all HLA types
- No need for adjuvants or delivery systems to be immunogenic
Correct Answer: Defined composition with minimized risk of infection and tailored epitope specificity
Q5. Which solid‑phase peptide synthesis strategy is most commonly used today for producing vaccine peptides at research and manufacturing scale?
- Boc/Bzl (tert‑butyloxycarbonyl) chemistry
- Fmoc/tBu (9‑fluorenylmethoxycarbonyl) chemistry
- Merrifield chlorotrityl chloride chemistry exclusively
- Rink amide coupling without protecting groups
Correct Answer: Fmoc/tBu (9‑fluorenylmethoxycarbonyl) chemistry
Q6. Which sequence is commonly incorporated into peptide vaccines as a universal CD4+ T‑helper epitope to improve helper responses across diverse HLA alleles?
- PADRE (Pan HLA‑DR‑binding epitope)
- HA tag sequence (YPYDVPDYA)
- FLAG tag (DYKDDDDK)
- Polyhistidine (His6) tag
Correct Answer: PADRE (Pan HLA‑DR‑binding epitope)
Q7. Why are small synthetic peptides often conjugated to carrier proteins such as KLH or CRM197?
- To decrease molecular weight and increase renal clearance
- To provide T‑cell help and enhance B‑cell activation and antibody responses
- To prevent any processing by antigen‑presenting cells
- To ensure peptides are poorly presented by MHC molecules
Correct Answer: To provide T‑cell help and enhance B‑cell activation and antibody responses
Q8. Which adjuvant class is most associated with promoting strong Th1‑biased cellular immune responses desirable for many peptide vaccines?
- Aluminum salts (alum)
- Toll‑like receptor 9 agonists (CpG oligodeoxynucleotides)
- Oil‑in‑water emulsions that exclusively induce Th2
- Monosodium glutamate
Correct Answer: Toll‑like receptor 9 agonists (CpG oligodeoxynucleotides)
Q9. In multi‑epitope peptide constructs, what is the primary rationale for including protease‑cleavable linkers between epitopes?
- To rigidify the construct and prevent processing by antigen‑presenting cells
- To allow intracellular processing and proper antigen presentation by MHC molecules
- To permanently fuse epitopes so proteases cannot separate them
- To increase hydrophobicity and reduce solubility
Correct Answer: To allow intracellular processing and proper antigen presentation by MHC molecules
Q10. What is a key immunological advantage of synthetic long peptides (SLPs) over short minimal epitopes?
- SLPs directly bind antibodies without processing
- SLPs favour cross‑presentation and generate stronger and longer‑lasting CD8+ T‑cell responses
- SLPs are always less stable and therefore safer
- SLPs do not require adjuvants for immunogenicity
Correct Answer: SLPs favour cross‑presentation and generate stronger and longer‑lasting CD8+ T‑cell responses
Q11. Which high‑throughput experimental technique is commonly used for linear B‑ and T‑cell epitope mapping of antigenic sequences?
- SPOT peptide arrays (synthesized peptide tiles on membrane)
- Western blot of whole cell lysates only
- Single‑cell RNA sequencing without peptide probes
- Conventional Gram staining
Correct Answer: SPOT peptide arrays (synthesized peptide tiles on membrane)
Q12. Incorporating non‑natural amino acids or D‑amino acids into vaccine peptides primarily aims to:
- Increase proteolytic stability and extend in vivo half‑life
- Guarantee MHC binding to all HLA alleles
- Prevent any antibody recognition entirely
- Eliminate the need for purification after synthesis
Correct Answer: Increase proteolytic stability and extend in vivo half‑life
Q13. The Multiple Antigen Peptide (MAP) system is characterized by which design feature?
- A linear single‑copy peptide chemically linked to lipids
- A dendrimeric branched lysine core presenting multiple copies of the peptide epitope
- A DNA plasmid encoding repeated epitope sequences
- A viral vector expressing one epitope repeat
Correct Answer: A dendrimeric branched lysine core presenting multiple copies of the peptide epitope
Q14. Native chemical ligation (NCL) is a valuable technique in peptide vaccine manufacture because it:
- Joins two peptide segments chemoselectively through an N‑terminal cysteine and C‑terminal thioester to form a native peptide bond
- Crosslinks peptides via random oxidation of methionine residues
- Allows enzymatic ligation by proteases only
- Is used to glycosylate peptides in a site‑specific manner
Correct Answer: Joins two peptide segments chemoselectively through an N‑terminal cysteine and C‑terminal thioester to form a native peptide bond
Q15. A major population‑level limitation of peptide vaccines arises from which immunogenetic factor?
- Universal expression of identical T‑cell receptors in all individuals
- HLA (MHC) polymorphism that affects peptide binding and presentation across different individuals
- Homogeneous B‑cell repertoires in the population
- Complete absence of antigen processing pathways in humans
Correct Answer: HLA (MHC) polymorphism that affects peptide binding and presentation across different individuals
Q16. Which laboratory assay directly measures cytolytic activity of antigen‑specific CD8+ T cells against target cells?
- Chromium‑51 (51Cr) release assay
- ELISA for total IgG
- Hemagglutination inhibition assay
- SDS‑PAGE protein profiling
Correct Answer: Chromium‑51 (51Cr) release assay
Q17. Cyclization of peptide epitopes (e.g., head‑to‑tail or disulfide bonds) is usually performed to:
- Increase conformational flexibility and susceptibility to proteases
- Decrease binding affinity for antibodies
- Stabilize conformation, increase resistance to proteolysis, and better mimic conformational epitopes
- Remove all tertiary structure to promote linear epitope formation
Correct Answer: Stabilize conformation, increase resistance to proteolysis, and better mimic conformational epitopes
Q18. Compared with KLH, the carrier protein CRM197 is often preferred because it:
- Is derived from marine organisms and induces no immune response
- Is a well‑characterized, non‑toxigenic diphtheria mutant used in licensed conjugate vaccines with defined manufacturing history
- Is cheaper but untested in humans
- Prevents antigen processing by APCs entirely
Correct Answer: Is a well‑characterized, non‑toxigenic diphtheria mutant used in licensed conjugate vaccines with defined manufacturing history
Q19. In MHC class I binding peptides, which positions are most commonly referred to as primary anchor residues?
- Positions 1 and 3
- Positions 2 and the C‑terminal residue
- Central positions only (e.g., 5–7) exclusively
- All positions are equally anchor residues for every allele
Correct Answer: Positions 2 and the C‑terminal residue
Q20. For regulatory quality control of a synthetic peptide vaccine, which parameter is essential to demonstrate biological activity prior to clinical testing?
- Presence of endotoxin alone without functional assay
- Potency assay showing induction of relevant immune response (e.g., antigen‑specific T‑cell activation or antibody generation)
- Only color and odor matching to reference
- Absence of any peptide impurities regardless of function
Correct Answer: Potency assay showing induction of relevant immune response (e.g., antigen‑specific T‑cell activation or antibody generation)
