ib 202- Immune System and COVID 19

3 important components of the SARS-COV-2 Structure

1) envelope

2) spike glycoprotein

3) RNA

ACE 2 Receptors

-proteins

-on oral mucosa, heart, lungs, colon

4 Steps of SARS virus entering cell

1) attachment of SARS- CoV-2 to the host cell

2) viral host membrane fusion and release of viral RNA

3) replication of virus components and new virions from viral RNA

4) release new viral particles

Immune System Defense against Infection

-when germs invade body they attack and multiply causing infection

-immune system fights infection

-blood contains white or immune cells to fight infection, different WBCs fight infection in different ways

SARS and Innate Immunity

-innate immunity eliminates SARS without activating adaptive immune system

-TLR detects RNA seq. and trigger IFN production, antigen presentation, and uncontrolled inflammation

-TLR7 genetic deficiency associated with severe disease

Cytokine Storms and SARS

-innate immune system disarms and destroys SARS

-macrophages and infected lung cells secrete cytokines and attract immune cells

-macrophages have ACE2 receptor

Why do COVID patients require a ventilator?

Adaptive Immunity and SARS

-virus presented in lymphoid organs evoke T helper cells activating humoral; and cellular immune responses

-antibodies and CD8+ T cells, antibodies neutralize virus

• CD8+ cells kill infected cells

SARS and Circulating Blood: Leukocytes

-SARS doesn’t infect circulating blood leukocytes since they don’t have SARS receptor

Vaccines

-develop immunity by imitating infection

-when infection goes away, body left with memory of T and B lymphocytes to remember how to fight disease in future

-takes a few weeks after vaccination to produce T and B lymphocytes

Vaccine Phases

phase I- small groups of people receive trial vaccine

phase II- clinical study expanded and vaccine given to people who have similar characteristics similar to those for who new vaccine is intended

phase III- vaccine given to thousands of people and tested for efficacy and safety