Persistence of Epstein-Barr Virus in Self-Reactive Memory B Cells
JOURNAL OF VIROLOGY
Authors: Tracy, Sean I.; Kakalacheva, Kristina; Luenemann, Jan D.; Luzuriaga, Katherine; Middeldorp, Jaap; Thorley-Lawson, David A.
Abstract
Epstein-Barr virus infection has been epidemiologically associated with the development of multiple autoimmune diseases, particularly systemic lupus erythematosus and multiple sclerosis. Currently, there is no known mechanism that can account for these associations. The germinal-center (GC) model of EBV infection and persistence proposes that EBV gains access to the memory B cell compartment via GC reactions by driving infected cells to differentiate using the virus-encoded LMP1 and LMP2a proteins, which act as functional homologues of CD40 and the B cell receptor, respectively. The ability of LMP2a, when expressed in mice, to allow escape of autoreactive B cells suggests that it could perform a similar role in infected GC B cells, permitting the survival of potentially pathogenic autoreactive B cells. To test this hypothesis, we cloned and expressed antibodies from EBV+ and EBV- memory B cells present during acute infection and profiled their self-and polyreactivity. We find that EBV does persist within self-and polyreactive B cells but find no evidence that it favors the survival of pathogenic autoreactive B cells. On the contrary, EBV+ memory B cells express lower levels of self-reactive and especially polyreactive antibodies than their uninfected counterparts do. Our work suggests that EBV has only a modest effect on the GC process, which allows it to access and persist within a subtly unique niche of the memory compartment characterized by relatively low levels of self-and polyreactivity. We suggest that this might reflect an active process where EBV and its human host have coevolved so as to minimize the virus's potential to contribute to autoimmune disease.
Construction and Antiapoptosis Activities of Recombinant Adenoviral Expression Vector Carrying EBV Latent Membrane Protein 2A
GASTROENTEROLOGY RESEARCH AND PRACTICE
Authors: Liu, Xishuang; Gao, Yu; Luo, Bing; Zhao, Youan
Abstract
To evaluate the possible effects of LMP2A (EBV latent membrane protein 2A) on human gastric cancer cell line SGC-7901, LMP2A coding gene was subcloned into shuttle plasmid pAdTrackCMV to form transfer plasmid pAdTrackCMV-2A, which was linearized with PmeI and cotransformed into E. coli BJ5183 with adenovirus genomic plasmid of pAdeasy-1. The identified recombinant adenovirus plasmid DNA was digested with PacI and transfected into 293 cells to package recombinant adenovirus particles named vAd-2A. Then the expression and antiapoptosis activities of LMP2A on SGC-7901 infected with vAd-2A were analyzed. The vAd-2A was successfully constructed and identified by PCR, restriction digestion, and sequencing. LMP2A expression in SGC was identified by strong green fluorescence expression with fluorescence microscopic photograph and Southern blotting. The growth of LMP2A expressing SGC cells was apparently improved. Both cyclin E expression and S phase ratio in LMP2A expressing SGC cells were upregulated by cell cycle analysis and confocal microscopic analysis respectively. The replication-deficient recombinant adenovirus vector can express LMP2A antigen in SGC cells and inhibit their apoptosis. The results indicate that LMP2A might play an important role in pathogenesis of EBV-associated gastric cancer (EBVaGC). This study establishes a foundation for further study on EBVaGC and its gene therapy.