Restricted Expression of Epstein-Barr Virus Latent Genes in Murine B Cells Derived from Embryonic Stem Cells

Background: Several human malignancies are associated with Epstein-Barr virus (EBV) and more than 95 % of the adult human population carries this virus lifelong. EBV efficiently infects human B cells and persists in this cellular compartment latently. EBV-infected B cells become activated and growth transformed, express a characteristic set of viral latent genes, and acquire the status of proliferating lymphoblastoid cell lines in vitro. Because EBV infects only primate cells, it has not been possible to establish a model of infection in immunocompetent rodents. Such a model would be most desirable in order to study EBV’s pathogenesis and latency in a suitable and amenable host. Methodology/Principal Findings: We stably introduced recombinant EBV genomes into mouse embryonic stem cells and induced their differentiation to B cells in vitro to develop the desired model. In vitro differentiated murine B cells maintained the EBV genomes but expression of viral genes was restricted to the latent membrane proteins (LMPs). In contrast to human B cells, EBV’s nuclear antigens (EBNAs) were not expressed detectably and growth transformed murine B cells did not arise in vitro. Aberrant splicing and premature termination of EBNA mRNAs most likely prevented the expression of EBNA genes required for B-cell transformation. Conclusions/Significance: Our findings indicate that fundamental differences in gene regulation between mouse and ma

Personality and longevity: findings from the Georgia Centenarian Study

Centenarians are thought of as unique and exceptional survivors. This study evaluated specific personality traits and configurations of traits among participants of the Georgia Centenarian Study. Two hundred and eighty five centenarians and their nominated proxies participated in this study. Self ratings and proxy informant ratings were obtained for different traits and facets of the Big-5 personality typology. Results suggested that centenarians overall had low levels of Neuroticism, but high levels of Extraversion, Competence, and Trust. When compared to centenarian self ratings, proxies provided significantly higher ratings for Neuroticism, Hostility, and Vulnerability, but lower ratings for Competence and Trust. Among Centenarians, the personality configuration of low Neuroticism, high Competence, and high Extraversion traits is over-represented relative to chance. The results confirm that centenarians show several unique single traits, but that a special combination of traits (i.e., low levels of Neuroticism, high Competence, and high Extraversion) are also notable in this group of exceptional survivors