Immune response to viral infection

Innate and adaptive immune system

- different components which react in different locations and time

- dendritic cells bridge innate and adaptive immune system through their ability to migrate and present antigen

• B cells and T cells see antigen in different ways (soluble, cell-bound)

• and cover different pathogenic locations (body fluids, intracellular infection)

B cells and T cells see antigen in different ways

 - antigen specific signal 1 (MHC/antigen)

- survival signal 2 (co-stimulation)

- cytokines regulate the differentiation

MHC-restricted antigen recognition, or MHC restriction, refers to the fact that a T cell can interact with a self-major histocompatibility complex molecule and a foreign peptide bound to it, but will only respond to the antigen when it is bound to a particular MHC molecule.[1]

mhc major histocompatibility complex

MHC: major histocompatibility antigens

Each allelic version has a different peptide binding

groove and presents a different set of peptides

HLA alleles influence antigen recognition, immune

response and disease prevalence/severity/susceptibility

• Co-stimulation is provided by dendritic cells

the environment

 Regulation of NK cells :

Inhibition of NK cells (MHC class Ia,

non-classical MHC class Ib)

Activation of NK cells (i.e. MICA/B)

Pathogens use diverse mechanisms to evade the

attack and clearance through the immune system

Neutralizing autoantibodies to type I IFNs underlie life-threatening COVID-19 pneumonia

CD4 cells, also known as helper T-cells, trigger the immune response by recognizing pathogens and secreting cytokines in order to signal to other immune cells, including CD8cells. CD4 cells are not directly responsible for the attack of the pathogens; on the other hand, CD8 cells, known as the cytotoxic T-cells, destroy the infected cells.

The immune reaction to SARS-CoV-2 infection is characterized by differentiation and proliferation of a variety of immune cells with immune mediator production and release, and activation of other pathogen resistance mechanisms.