A Rabbit Model of Epstein-Barr Virus Infection

PROJECT SUMMARY
Epstein-Barr virus (EBV) is a herpesvirus that persists as a notable human pathogen with significantoncogenic potential that is related to its ability to establish lifelong latent infection within an immunocompetenthost. Unlike for the vast majority of viruses, EBV-associated diseases are almost exclusively a consequence oflatent infection instead of damage caused by virus replication. Latency poses significant problems, for example,in the development of effective anti-EBV therapeutics, since the majority of such compounds are designed totarget viral polymerases and other proteins active only during virus replication; novel approaches are thereforeneeded to target latent EBV infection. Moreover, the ubiquitous nature of EBV (~95% infected by adulthood) andthe highly evolved equilibrium that it has established within the human immune system, make development ofan effective vaccine challenging. Both of these challenges could be greatly aided by a biologically accurate andtractable animal model of EBV infection, which currently does not exist. Surprisingly, several reports over thelast decade have provided support for the laboratory rabbit as a model of EBV infection. In preliminary work, wehave confirmed the most salient observations from these earlier studies, confirming that rabbits are indeedinfectable, as indicated by persistence of the viral genome and expression of EBV genes associated with boththe latent and productive stages of the virus lifecycle. However, several critical demonstrations are required tosupport authenticity of this model, and thus the extent to which it could be applied experimentally. In thisapplication, we propose three specific aims to fill these gaps through complementary efforts by two seniorinvestigators in the EBV field, and a third who has considerable expertise in the use of the rabbit as a model forvirus infection and immune-related studies. Under Aim 1, Dr. Clare Sample will assess EBV infection in theepithelial cell component of the lifecycle, including the use of organotypic (raft) cultures of primary epithelium, amodel she has developed and used to define EBV infection in human epithelium. Under Aim 2, Dr. JefferySample will employ his expertise in the field of EBV latency to direct studies to elucidate whether establishmentof a persistent infection in rabbit B cells is mechanistically comparable to the process that occurs in the humanB-cell compartment. Finally, Dr. Neil Christensen, employing his expertise with the rabbit model will support workunder Aims 1 and 2, and in Aim 3 will assess the humoral and cell-mediated immune responses to EBV infectionin the rabbit, and whether they are comparable to key aspects of the adaptive immune response to EBV infectionin the natural host. In summary, the proposed work will inform us whether the three basic host components thatdictate EBV biology in its human host are equivalently functional in the rabbit: 1) Whether rabbit epitheliumsupports EBV replication that is critical for passage of the virus onto a naïve host; 2) Whether persistence ofEBV in rabbit B cells is established through an authentic latent infection; and 3) Whether a comparable adaptiveimmune response is mounted to EBV infection in the rabbit.