Modulation of epstein-barr virus latent membrane protein 1 activity by intrabodies

Objective: The Epstein-Barr virus (EBV) has been implicated in the development of many human neoplasias including B lymphoma and nasopharyngeal carcinoma. EBV latent membrane protein 1 (LMP1) is essential to virus-induced B cell immortalization and the downregulation of cell adhesion molecules that increases cell motility. Therefore, identifying LMP1 activity modulation methods may lead to the development of new therapies for LMP1-positive tumors. Methods: This study uses a phage display single-chain variable fragments (scFvs) library to screen recombinant antibodies specific to the LMP1 C terminal region. A total of 45 individual clones were obtained, and these scFvs were cloned as intrabodies and transfected into LMP1-positive cells. Results: One of the scFv clones, designated H3, was capable of reducing LMP1-mediated NF-κB activation in HEK293 cells. Immunofluorescence and co-immunoprecipitation studies show that scFv H3 could interact with LMP1 in vivo. In addition, expression of scFv H3 intrabody could reduce cell motility in MDCK-LMP1 cells in the transwell migration assay. Conclusion: These data indicate that scFv H3 intrabody can inhibit LMP1 functions in epithelial cells and may be useful for attenuating the LMP1 function in LMP1-positive tumors.