Aalaa Abdalla

United Arab Emirates

Using a Novel Rabbit Model of EBV Infection to Understand the Dynamics of EBV-induced Lymphoproliferative Disease in Immunocompromised States

Aalaa Albasha1, Atia Rasheed1, Pretty Philip1, Gulfaraz Khan1

1. Department of Microbiology & Immunology, College of Medicine and Health Sciences, UAE University, Alain- UAE

Abstract

Background

Epstein-Barr virus (EBV) is well known to be associated with the pathogenesis of lymphoproliferative disorders (LPD). However, the exact mechanism by which EBV induces lymphomas is still poorly understood. During lymphomagenesis, infected cells escape the body’s immune surveillance by entering into different types of viral latencies. One of the common types of EBV-related LPD is post-transplantation LPD (PLPD). It is usually a consequence of using immunosuppressive drugs such as Cyclosporine A (CsA). To unravel the molecular mechanism of EBV-induced lymphomagenesis, an in vivo experimental model is required. Our previously published research has shown that young rabbits are susceptible to EBV and the infection mimics what has been observed in humans.

Methods

40 white New Zealand rabbits were brought and left for two weeks to acclimatize in our animal house. The animals were divided into 3 groups: EBV-/CsA- (G1), EBV+/CsA- (G2), and EBV+/CsA+ (G3). G2 and G3 were infected intravenously with EBV, whilst the animals in G1 were kept as non-infected and untreated controls. G3 animals were started on daily injections of CsA (10mg/kg) for up to 5-weeks. Blood was collected weekly and a proportion of the animals from each group were sacrificed at weeks 2, 3, 4 and 5. All major organs and tissues were collected and preserved. Different histological and molecular assays, such as hematoxylin and eosin (H&E), trichrome stain, EBER in situ hybridization (EBER-ISH), and immunohistochemistry (IHC), were used to analyze EBV and its associated pathology. Quantitative PCR was done to detect the virus copy numbers in blood, spleen, and liver samples.

Results

At necropsy, abnormal features were noticed, like cystic and nodular spleens, hepato-splenomegaly, lung bleeding, and tonsils enlargement. Moreover, an observable variation in spleen size and texture among different animal groups was detected. Primary microscopical analysis showed notable disruption of normal spleen structures, fibrosis, and early signs of lymphoma formation in some cases. Additionally, EBV could be localized at various organs by EBER-ISH, and abundant expression of viral oncoprotein, latent membrane protein (LMP1). At molecular level, qPCR revealed relatively high EBV copy numbers in different type of tissues.

Conclusions

We show, for the first time in a controlled manner, that (1) EBV is associated with pathological changes reminiscent of early lymphomagenesis in immunosuppressed states, (2) LMP1 is likely to be a key viral player in the process, (3) other viral and cellular factors need to be evaluated to build a comprehensive picture, (4) the rabbit model of EBV is ideal for studying the virus and its associated pathologies.