Question

7. During an exciting adventure through the rainforests of Papua New Guinea, you unfortunately inhale a previously unidentified virus. Describe the events that occur to allow your body to a) process the virus, b)display it to the adaptive immune system, c)activate and differentiate the appropriate type of T-cell and d)use those T-cells to direct the elimination of the viral source.

Answer 1

Question 7 :-

The events that would occur in the body in the above mentioned scenario are as follows :-

• Once a virus gains successful entry into the body of the host, it starts infecting the host cells and replicating inside them. now, the immune system immediately does not know that the host cells have been infected and neither can they detect the entry of the virus. So to overcome this problem, the immune system makes use of certain specialized structures called MHCI molecules. These MHCI molecules display parts of the viral protein present inside the infected cell on the surface of the cell. This serves to mark the infected cells so that they can now be easily detected by the cells of the immune system.
• After the infected cells have been successfully marked by using the MHCI molecules, now comes the role of the cytotoxic T cells. The T cytotoxic cells are actually specialized T-cells that combat viruses. These T cells keep circulating and once they encounter the cells displaying the viral peptides along with the MHCI molecules, they attach to these cells using a structure called the T cell receptor (TCR). Once the virally infected cell gets bound to the T cytotoxic cell via the T cell receptor, this sends a signal to the T cell which in turn makes the T cell to release certain cytotoxic factors that kill the virally infected cell.
• The cytotoxic T cells have certain enzymes inside them that help in the process of destroying the virally infected cells. One of them is perforin. Once released, perforin creates pores on the surface of the target cell. As soon as the target cell surface gets perforated with pores, a second class of enzymes called as granzymes enter through these pores. Once inside the target cell, they initiate a process called as programmed cell death or apoptosis. Apart from this, there are other enzymes called granulysins that are released by the T cytotoxic cells. These enzymes destroy the target cells by a direct lysis of the cell. Also there are other factors called cytokines that are released by the T cytotoxic cells that enhance the fight against the target cells.