Question

People infected with SARS- CoV-2 (the coronavirus that causes COVID-19) can show an array of different symptoms and complications, ranging from mild to severe. Researchers are working to develop both prevention and treatment, including vaccines and antibody injections.

Vaccines introduce antigens from viruses, without introducing the infectious virus itself. How/why do vaccines act as prevention rather than treatment? Be sure to talk about the types of cells and immune responses that vaccines are targeting, and why targeting these cells and responses are preventive.

Answer 1

Vaccines are acts as preventive rathrer than treatment because the vaccines are injected before actual disease come to the body. In vaccination we inject inactivated pathogen or killed pathogen. It does not cause any illness and memorise the cells which cause illness.

The cells involved in vaccination are

1. Macrophages
2. B-lymphocyts
3. T-cells

Ater vaccination, Macrophages react to the antigen in vaccine, and produce MHC (Major histocompatability) molicule in their surface. When T - cells react with MHC molicule it activates and proliferated into

• cytotoxic T cells
• T - helper cells
• Supressor T cells

Ctotoxic t- cells kill the pathogen infecting cells

Supressor t cells invoved in T cells regulation

T- helper cells used for generation of anti bodies and  memory B- cells.

After vaccination, B lymphocytes detect the antigens in the vaccine. The B lymphocytes will react to antigen and produce MHC on their surface. The T- helper cells react to MHC molicule in B - lymphocytes produce  "lymphokines" . These lymphokines are used to differentiate the B- cells into

• plasma cells
• memory B cells.

The plasma cells produce the antibodies (Y-shaped molecules), which are trained specifically to attack  and inactivate the pathogen you are being vaccinated against.

Memory B- cells are resosible for long lasting momory of the vaccinated pathogen