2006 Fiscal Year Final Research Report Summary
Study on the mechanism by which EB virus LMP genes modify B cell development in host
| Project/Area Number |
17590417
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Virology
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| Research Institution | Osaka University |
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Principal Investigator |
YASUI Teruhito Osaka University, Research Institute for Microbial Diseases, Research Associate, 微生物病研究所, 助手 (60283074)
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| Project Period (FY) |
2005 – 2006
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| Keywords | Epstein-Barr virus / B lymphocytes / Latent membrane protein / Lymphomagenesis / Transgenic mouse / Herpesvirus / Growth transformation / B cell antigen receptor |
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| Research Abstract |
Epstein-Barr virus (EBV) has tropism for the human B lymphocytes and epithelial cells and widely infects into 95% of human being in the world-wide. It is also known that EBV is a causative reagent to be associated with Burkitt's lymphomas, Hodgkin's lymphomas, AIDS-associated lymphomas. EBV escapes immunosurveillance when it infects and induces its tumorigenicity in B lymphocytes but little is known about the molecular mechanisms by which EBV invades well in human. lb clarify the mechanism, here we tried to show how EBV latent gene products contribute to EBV-induce B cell growth transformation and activation in viva First of all, we generated transgenic mice (tg) with B cell-specific expression of EBV nuclear antigen (EBNA1) which is involved in the EBV genome maintenance in cells and the growth transformation by stabilizing p53 tumor suppressor protein. They carry EBV EBNA1 gene under the control of Ig enhancer/polyoma immediate early gene promoter to give EBNA1 expressed in B cells s
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pecifically. EBNA1tg showed hyperplasia in the spleen and lymph nodes where B cells express large amount of EBNA1 protein. There is no difference in the incidence of tumorigenicity between EBNA1tg and the control suggesting that tumorigenicity of EBV would be dependent on the other EBV latent gene such as LMP1 and EBNA1 and that it could be on the diversity of genetic background in human which is susceptibility for EBV. The second aspect was that how in vivo system could be established for searching the pathogenesis of EBV on B cell growth transformation induced by latent membrane proteins (LMP). The data have been shown that the expression of LMP including LMP1 and LMP2a inhibit and modify B cell development at the late stage, especially, the transition of follicular B cells to germinal center B cells in secondary lymphoid organs. In this context, it is difficult to determine the involvement of LMP in lymphomagenesis to develop Burkitt's lymphomas, Hodgkin's lymphomas which are thought to be derived from germinal center B cells. lb overcome the difficulties, we developed more sophisticated drug-inducible LMP expression system in mouse where early B cell development was defective in inducing LMP1 expression suggesting that LMP1 is responsible for escaping host immunosurveillance in the EBV infection. Less
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