mRNA vaccines for COVID-19 (BNT162b2, mRNA-1273) are formulated with lipid nanoparticles (LNPs). The primary role of LNPs is:
- A To act as an adjuvant by activating innate immune toll-like receptors
- B To protect mRNA from RNase degradation and facilitate cellular uptake and endosomal escape ✓
- C To prolong the half-life of spike protein in circulation
- D To target antigen-presenting cells exclusively in lymph nodes
Correct answer: B. To protect mRNA from RNase degradation and facilitate cellular uptake and endosomal escape
Explanation
mRNA is inherently unstable and would be degraded rapidly by ubiquitous RNases if administered naked. Lipid nanoparticles encapsulate the mRNA, protect it from enzymatic degradation, and facilitate endocytosis into cells; the ionisable lipid component promotes endosomal escape, releasing mRNA into the cytoplasm where ribosomes translate the spike protein. LNPs do have some adjuvant properties but their primary function is delivery. The vaccine remains at the injection site (deltoid muscle and draining lymph nodes) rather than circulating systemically.
Reference: Ananthanarayan & Paniker's Textbook of Microbiology, 11th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.