Attempts to visualize lymphocytes latently infected with Marek’s Disease Virus in situ

Marek’s Disease (MD) is an avian lymphoma disease caused by an alphaherpesvirus, Marek’s Disease Virus (MDV). Live attenuated vaccines can protect birds from the disease but do not inhibit MDV infection. The co-infection of vaccine virus and virulent MDV perhaps contributed to the emergence of MDV strains that caused vaccine breaks. MDV establishes lytic and latent states of infection but it is during latency that cells can be transformed. This thesis strived to create a tool to visualize latently infected cells that would help reveal the transformation process and underlying mechanisms of the vaccine effect. Toward the goal, I constructed two recombinant MDVs that were designed to express a fluorescent protein during latency. The recombinant MDVs were able to replicate successfully in vitro and in vivo comparatively to parental MDV. They also expressed the fluorescent protein in the infected cells in vitro. However, the expression of the fluorescent protein was not confirmed in vivo and these recombinant MDVs did not cause lymphomas in infected birds.