Regulation and Reproduction

Question

Explain how the specific immune response differs between two patients who have been infected with the same virus. Patient A was previously vaccinated against the virus, while patient B has no previous exposure to the virus.

Answer 1

The basis of an effective vaccine is to expedite the activation of cell-mediated immunity. When given a vaccine or infected naturally, the body is exposed to an antigen which in the event of a viral particle, is consumed by proteosomes into peptide fragments, and through the rough ER and golgi apparatus are presented on MHC class I molecules which ultimately allow for antigen presentation and activation of cytotoxic T-cells via CD8 and TCR receptors. These cells release cytotoxic granules that result in the death of the cell and its associated viral load. The now activated T-Cells proliferate and form clonal cells and memory cells. These memory cells are the key here, memory cells allow for a faster immune response when the body is presented with an antigen that activates these cells. When a patient receives a vaccine to a virus this memory cell formation is achieved without the drawbacks of stimulating the non-specific cellular and molecular defenses (in most cases, although fever-like symptoms are a potential) including fever, and inflammation. It is these non-specific side effects that can be responsible for adverse events in those with infection.

It is not that the two patients undergo different responses entirely (vaccinated vs unvaccinated) it is more so that those patients who are vaccinated already have memory cell formation and therefore have a quicker response to the infection to which they have been vaccinated and often clear said infection prior to the onset of symptoms.