**2.4.1 EBV infection**

EBV is tightly related to the development of many human cancers. Chen et al (Chen, Divisconte et al. 2005) has developed a BAC-GFP-EBV (containing 172-kb of the EBV genome) system to monitor early cellular and viral events associated with EBV infection. BAC-GFP-EBV was transfected into the HEK 293T epithelial cell line (Halder, Murakami et al. 2009). Then the progeny virus produced by a chemical was used to immortalize human primary B-cell which can be easily monitored by green fluorescence and proliferation. The results showed a dramatic increase in Ki-67, CD40, and CD23 signals. The viral genes express a pattern of an early burst of lytic gene expression. This up-regulation of lytic gene expression prior to latent genes during early infection strongly suggests that the resulting progeny virus is capable of infecting new primary B-cells (Halder, Murakami et al. 2009). This process may be critical for establishment of latency prior to cellular transformation (Halder, Murakami et al. 2009).
