Atia Rasheed

U.A.E.

Using a rabbit model to unravel the link between EBV infection and vitamin D in the pathogenesis of multiple sclerosis

Atia Rasheed1, Meera Al Ameri1, Pretty Philip1, Latifa Al-Khyeli2, Javed Yasin3, Gulfaraz Khan1
1. Department of Medical Microbiology and Immunology
2. Department of Pathology
3. Department of Internal Medicine
College of Medicine and Health Sciences, UAE University, Tawam Hospital Campus, Al Ain, UAE.

Abstract

Background

The aetiology of multiple sclerosis (MS) is complex and not fully-known. However, genetics and several environmental factors have been implicated in disease pathogenesis. Of the environmental factors, Epstein-Barr virus (EBV) and low vitamin D levels have been implicated. Although numerous studies demonstrated that vitamin D supplementation could help to control EBV infection and diminish disease activity in MS patients, the interaction of these two risk factors remains poorly understood. One major obstacle in addressing EBV-associated questions has been the lack of a suitable animal model of EBV infection. This study aimed to investigate the impact of vitamin D on EBV infection and its role in MS pathogenesis by using our recently established novel rabbit model.

Methods

The study was conducted on 40 New Zealand White rabbits (NZW), randomly divided into two major groups: vitamin D deficient (Vit D-) and vitamin D supplemented (Vit D+) groups. Each group was further subdivided into EBV+ and EBV- groups. EBV+ groups received 1ml of cell culture-derived virus via the marginal ear vein of the rabbit. On the day of virus inoculation, Vit D- group was fed with vitamin D-deficient diet, and oral Vit D supplementation was given to Vit D+ group, every other day for two weeks. On day 15 post-infection, all the animals were euthanized. Blood and all major organs were harvested and stored for downstream analysis.

Results

Macroscopic and microscopic examination of spleen revealed substantial differences between the Vit D+ and Vit D- groups. Interestingly, qPCR analysis of PBMCs, spleen, and liver showed a significantly higher viral load in the Vit D+ group compared to the Vit D- group. Moreover, EBER-in situ hybridization and immunohistochemistry revealed extensive infection in the Vit D supplemented animals compared to the other Vit D deficient animals.

Conclusions

Contrary to what has been suggested, we show, for the first time in a controlled manner, that vitamin D levels correlate positively with the viral load. Our data suggests that elevated vitamin D levels are associated with high viral load. One possible explanation is that an excessively high vitamin D could dysregulate the immune system. Thus, resulting in enhanced survival and higher viral load in the Vit D+ group. These novel findings highlight the complex relationship between EBV and vitamin D and warrant further investigations. Such studies could shed light on new strategies for controlling EBV infection in MS development.