Question

Q-14 & 15 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.

Q-14: Which of the following molecules can interact with LMP2A in B cell plasma membrane? A. ZAP-70, B. Lck, C. Syk, D. PLC, E. SLP-65 BIO 4226 Immunology

Q-15: Choose the correct answer about the following question With LMP2A of EBV, Dr. Immunob has recently generated a plasmid construct encoding “AlwaysY-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. I. 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 NFB activation will be observed in these B cells. A. I, B. II, C. III and IV, D. I and III and IV, E. I and II and III and IV

Answer 1

14). C. Syk

LMP2A has important roles in modulating B-cell receptor (BCR) signal transduction by associating with the cellular tyrosine kinases Lyn and Syk via specific phosphotyrosine motifs found within the LMP2A N-terminal tail domain ... In Epstein-Barr virus-transformed B cells, known as lymphoblastoid cell lines (LCLs), LMP2A binds the tyrosine kinases Syk and Lyn, blocking B-cell receptor (BCR) signaling and viral lytic replication....

15). Some more information is needed