Viral pathogenesis

The lytic form of EBV infection is required for the production of progeny virus, and is thus essential for cell-to-cell spread of the virus, as well as transmission from host to host. Unfortunately, there is currently no cell culture system in vitro that is permissive for efficient primary lytic EBV infection. Although a recent report suggests that allowing the virus to first attach to the surface of primary B cells greatly facilitates EBV infection of epithelial cells in vitro (Shannon-Lowe et al., 2006), even this system of infection still does not result in efficient horizontal spread of virus from cell to cell. Thus, lytic EBV infection in vitro has been studied by reactivating the lytic form of infection from latently infected cell lines using a variety of inducing agents, including phorbol esters, butyrate, calcium ionophores, and B-cell receptor stimulation.

During primary infection, EBV probably initially infects oral epithelial cells in a lytic form, and then subsequently infects B-cells, where the virus usually assumes one of the latent forms of infection. In contrast to alpha and beta herpesviruses, which cause human diseases during the lytic form of viral infection but are essentially innocuous while in the latent form of infection, most illnesses attributable to EBV infection are associated with the latent forms of infection. During primary EBV infection, some individuals, particularly adolescents, develop the syndrome infectious mononucleosis (IM) approximately 1 month after being infected (Cohen, 2000; Jenson, 2000).