RAS question
mRNA vaccines work by:
Correct answer: (D) Introducing messenger RNA that instructs cells to produce a viral protein, triggering immune response.
mRNA vaccines work by introducing messenger RNA that instructs human cells to make a viral protein, which then triggers an immune response.
Explanation
mRNA vaccines do not place a live or weakened virus into the body. They deliver synthetic mRNA encoding the spike protein, and the World Health Organization describes the same mechanism: mRNA vaccines provide human cells with instructions to make part of the SARS-CoV-2 spike protein. Once inside cells, the mRNA is translated into a protein antigen. That antigen is recognised by the immune system, which induces an immune response, including T-helper cells, cytotoxic T cells and antibodies. This is why option D is the correct description: the vaccine supplies genetic instructions for a viral protein, not the virus itself or ready-made immunity.
Why the other options are wrong
- (A) mRNA vaccines use synthetic messenger RNA to give cells protein-making instructions, not bacterial DNA.
- (B) They stimulate the recipient's immune system to produce antibodies; they do not inject ready-made antibodies.
- (C) The WHO mechanism describes mRNA inside a lipid coat and translation into an antigen, not injection of a weakened live virus.
Concept
This tests biotechnology in vaccine platforms, especially how nucleic-acid vaccines differ from live, inactivated and antibody-based approaches. It recurs in RAS because public-health technology questions often ask the mechanism, not just the vaccine name.