Question

would occur during a viral infection. (8 pts) gh 8, with 1 being the first and 8 being the last) as they IFNAR1/2 is bound by ligand NK cell identifies the cell as healthy and does not kill it Type I interferon-stimulated genes are induced Type 1 Interferons all are secreted by virally-infected cells I protein expression on the plasma membrane becomes elevated STAT proteins are phosphorylated NK cell inhibitory receptor-mediated signaling increases JAK and Tyk2 are activated 3. Briefly describe the NK cell killing mechanism by answering the following questions: a) vvhat triggers NK cells to release their granules? b) what proteins are contained in the NK cell granules that are critical for killing? c) What is the role of each of granule protein in cell killing? (6 pts) 6. A mother has a germ line mutation in the Toll Like Receptor 4 gene. a) Will her children have this mutation? b) Briefly explain your reasoning. c) Will her children be affected by this mutation? d) Briefly explain your reasoning. e) Briefly explain the functional importance of TLRs within the context of an immune response. (10 pts)

Answer 1

Question 4

Answer: The order of events that occur during viral infection.

Step 1: Type 1Interferons α/β are secreted by virus infected cells.

Step 2: IFNAR 1/2 is bound by ligand.

Step 3: JAK andTyk2 are activated.

Step 4: STAT proteins are phosphorylated.

Step 5: Type 1 interferon stimulated genes are induced.

Step 6: MHC I protein expression on the plasma membrane becomes elevated.

Step 7: NK cell inhibitory receptor-mediated signaling increases.

Step 8: NK cells identifies the cell as healthy and does not kill it.

Question 5:

Answer: Natural killer (NK) cells are a part of innate immune system and are large granular cytotoxic lymphocytes. They produce rapid response to cells infected with virus. NK cells express CD16 receptor, which recognizes antigen-antibody complex on the infected cell. Upon recognition, NK cells gets activated and release cytoplamsic granules to kill the infected cells. NK cells also gets activated by interferons or cytokines, which are stress molecules secreted by viral infected cells.

Nk cell granules contains proteins such as perforin and granzymes (serine proteases) that are critical for killing. The protein perforin creates aquatic pores or channels in the membrane of the infected cell allowing granzymes and other molecules enters in to the infected cell. Granzymes induces apoptosis and kill the infected cells.