Question

SARS-CoV-2 is a novel coronavirus that causes a respiratory disease called COVID-19. The immune system is activated after the virus gains entry to the human cells. With your knowledge from the immunology course describe very briefly the process of antigen processing and presentation for viruses in terms of major histocompatibility (MHC).

Answer 1

When a foreign antigen enters the human body it evokes an immune response. Infection of human body with bacteria and virus stimulates cell mediated humoral immune system that condists of B and T lymphocytes.
B lymphocytes are involved in antibody production against the foreign antigen while t lymphocytes help in lysis and killing of antigen through cytokine production.
When a viral cell infects the cell, it enters the cell cytosol and results in protein unfolding and mutations. This results in release of peptide fragments into the cytosol. The MHC I proteins binds to these peptides and are represented to the cytotoxic t cells with the help of antigen presenting cells.
Once presented, cytotoxic t cell recognises the antigen presenting cell through presence of t cell receptors. Cytotoxic t cells then initiates an immune response and causes lysis and killing of the infected cell.