Question

Is option 1 true or false?

Transfected B cells will not become immortalized. It is immortalized when the B cell contain EBV episomes along with 9 virus encoded protein--> false?---> answer C

The Dr. is altering a virus encoding protein and for this to happen i'm assuming he would do this in vitro so they will become immortalized. Earlier in the problem it states "B lymphocytes inf. with EBV & grown in vitro are immortalized & termed LCL which contain EBV episomes & 9 encoded proteins, 1 of them is LMP2A--->true?---> answer D

Epstein-Barr virus (EBV) is a common human pathogen that is associated with a variety of hemopoietic cancers such as a African Burkitt's lymphoma, Hodgkin's disease, adult T-cell leukemia, and lymphoproliferative diseases. B lymphocytes infected with EBV and grown in vitro are immortalized and are termed lymphoblastoid cell lines (LCLs). These EBV-transformed LCLS contain EBV episomes and nine virus-encoded proteins. One of them is LMP2A. The LMP2A protein localizes to numerous small patches in the plasma membrane of the infected B lymphocytes. Within the 119-amino-acid amino-terminal domain of LMP2A there are 8 tyrosine residues. 2 of which form an immunoreceptor tyrosine-based activation motif (ITAM). Antigen-induced B-lymphocyte proliferation and differentiation result from the sequential activation of protein tyrosine kinases and their interaction with phosphorylated ITAMs. The 119- amino-acid cytoplasmic amino-terminal domain of LMP2A is essential for the pathogenic effect of EBV. With LMP2A of EBV, Dr. Immunob has recently generated a plasmid construct encoding "Always- Y-phospho-LMP2A" protein, which is a modified form of LMP2A. "Always-Y-phospho-LMP2A" can not only be constitutively clustered at the plasma membrane, but also maintain the tyrosine phosphorylated status at the ITAM motif of LMP2A. When B-cells are transfected with this expression construct of "Always-Y-phospho-LMP2A", what consequence(s) can you expect to observe? Find a correct combination from the following indications 1. The transfected B cells will become immortalized. II. B-cell receptor (BCR)-induced signaling will be reduced in these B cells. III. Increased PIP3 production will be observed in these B cells. IV. Increased NFKB activation will be observed in these B cells. A. 1, B. II, C. III and IV, E. I and II and III and IV D. I and III and IV,

Answer 1

The answer should be D.

Explanation: Statement -1: The transfected B-cells will be immortalized. Here, main factor causing the immortalization is EMV. Also, LMP1 is known to be essential for transformation.

Statmenent-4: LMP1 has no intrinsic enzymatic activity but instead aggregates the cellular proteins of the TNF (Tumour Necrosis Factor) receptor signaling pathway to activate transcription factor NF-κB. Thus, EBV-mediated growth transformation is genetically and biochemically linked to LMP1-mediated activation of NF-κB.

Statement-2: Since, B-cells have become more active now, B-cell induced receptor signalling would be rather increased. Thus, this statement is false.

Statement-3:  Growth of B-cells microclusters are regulated by PIP3 signalling. Since the plasmid contains 'always phosphorylated LMP-2', the signalling pathway will be activated causing PIP3 production.