Question

1. Research is coming out daily about COVID-19. One area of study is the primary versus second response infection response.
   1. Describe innate immunity to COVID-19.
   2. If a vaccine is approved, describe the adaptive immunity.
   3. What is the difference between primary and secondary responses, on a antibody/antigen level?
   4. Can a virus, like COVID-19, evade host defenses?

Sources?

Answer 1

Answer a) The innate immune system is essentially made up of physical barriers  that aim to keep viruses, bacteria, parasites, and other foreign particles out of your body or limit their ability to spread and move throughout the body.

Innate immune response cells secrete interferons1 and other chemicals (cytokines), Interferons interfere with virus replication .

1 Interferons and cytokines cause fever, muscle aches, etc - the early symptoms of COVID -19 virus  infection .

2. A ‘weaker’ innate response (e.g. in elderly people or those with underlying health problems) may result in delayed stimulation of the adaptive response

3. Patients who had mild or asymptomatic COVID-19 have low levels of neutralizing antibodies (or even undetectable levels),In these persons it is possible the innate immune response and the T cell response cleared the virus .

Answer b) . If a vaccine is approved addaptive response will take place -

Adaptive immune response to the infection starts after 6 - 8 days

Adaptive response include two types of white blood cells

• T cells (cellular response)
• B cells (antibody response)

T- cells recognize cells that are infected with a specific virus and rapidly increase in number to tackle the infection.

• There are two types of T cells-
• CD8+ cytotoxic T cells kill the cells in which the virus is multiplying and help to slow down or stop the infection.

CD4+ helper T cells bring in other cells of the immune system and stimulate B-Cells to produce antibodies specific to that virus

B cells produce produce antibodies that are specific to that virus, that is IgM antibodies are produced first and disappear after a few weeks and IgG antibodies are produced at the same time or 2-3 days later, and titres (levels) usually remain for months .

Answer c) primary response is s the reaction of the immune system when it contacts an antigen for the first time.And a later contact of the host with the same antigen will induce a more rapid and heightened secondary immune response.  Because antibodies are already developed due to primary response .

Answer d) SARS-CoV-2 suppressed protein production in the host, including that of proteins active in cellular anti-viral defense mechanisms.

virus ensure its own replication and propagation in human hosts and can have a devastating effect on host cells.It binds with human genome protein and it almost completely prevented production of various immune molecules that fight viral infection, such as interferons.