Question

1. Given what you know about the immune response, propose a detailed explanation about how the immune system responds to COVID-19. Be sure to describe each phase (physical barriers, non-specific immunity, specific immunity). You may draw a step by step diagram labeled or your may describe the process in words Be sure to address the role of macrophages, NK cells, B cells, and T cells.

Answer 1

ANSWER :-

1. Innate immunity is the inborn ability of the body to fight against the introduced pathogens. This includes physiological barriers such as skin and most importantly the hairs in the nasal passage. Although, in case of SARS-Cov-2 virus, these natural barriers are not effective in restricting viral entry, it should be taken into consideration that the virus mainly enters the respiratory tract through the nasal and oral passages.
2. One of the major part that should be included in this answer is about the Natural killer cells and the macrophages that forms an integral part of the innate immune response. The Macrophages and the dendritic cells are also called as the antigen presenting cells provided with their ability to present a small part of the virus called as the antigen on their surface so as to attract the cells of the adaptive immune system.
3. But, in most of the cases associated with the viral infection (COVID19), the response that has been mediated by the macrophages is not quite evident to the adaptive immunity cells taking into consideration the phenomena of hyperinflammation which can lead to damage of associated blood vessels and tissues which can prompt enhanced viral infection. In such cases, the role of the natural killer cells comes into existence.
4. As the name suggest they can either directly destroy the viral particles or they can send a signal to the cells of the adaptive immune system to carry out an attack on the viral population. This cell cascade events is being mediated in the presence of cytokines namely interferon gamma along with tumor necrosis factor which in turn enhances infiltration and recruitment of the cells like the T-helper cells and the cytotoxic T-cells.
5. But, major role has been seen in the proliferation and the maturation (differentiation) of the B-cells into the plasma cells and the memory cells in which the latter is the major scope for long-term immunization against the potent virus.
6. Patients with this infection shows high levels of certain immunoglobulins like IgG and the T-lymphocytes namely the helper T-cells that helps in the cell signaling cascade event. The major advantage of the natural killer cells is the ability to differentiate between the self and the non-self cells in order to mediate a specific and effective immune response.
7. The virus possesses spike proteins which are able to bind to certain receptors called as the Angiotensin converting Enzyme 2 (ACE2 receptor) with high specificity and are able to inhibit the process of recognization by the innate and the adaptive immune response so as to increase their time of infection and thus chances of survival.
8. The ultimate goal of the immune system is to generate immune memory which would prove beneficial if the virus reenters the body and is thus detected by the body's immune system. This can be achieved only through the adaptive immune response by means of activating the stem cells pathway to generate the memory B-cells and the plasma B-cells. These play a vital role in neutralizing the antigens or the viral particles thereby clearing out the viral load rendering them ineffective of further pathogenecity.