Citation: Reguraman, N.; Hassani, A.; Philip, P.S.; Pich, D.; Hammerschmidt, W.; Khan, G. Assessing the Efficacy of VLP-Based Vaccine against Epstein-Barr Virus Using a Rabbit Model. Vaccines 2023, 11, 540. https://doi.org/10.3390/ vaccines11030540 Academic Editors: Yasir Waheed and Khalid Muhammad Received: 14 December 2022 Revised: 2 February 2023 Accepted: 3 February 2023 Published: 24 February 2023 Copyright: © 2023 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/). Article Assessing the Efficacy of VLP-Based Vaccine against Epstein-Barr Virus Using a Rabbit Model Narendran Reguraman 1,† , Asma Hassani 1,‡ , Pretty S. Philip 1 , Dagmar Pich 2 , Wolfgang Hammerschmidt 2 and Gulfaraz Khan 1,3, * 1 Department of Microbiology and Immunology, College of Medicine and Health Sciences, United Arab Emirates University, Al Ain P.O. Box 15551, United Arab Emirates 2 Research Unit Gene Vectors, Helmholtz Zentrum München, German Research Center for Environmental Health, 25, D-81377 Munich, Germany 3 Zayed Center for Health Sciences, United Arab Emirates University, Al Ain P.O. Box 15551, United Arab Emirates * Correspondence: g_khan@uaeu.ac.ae; Tel.: +971-3-7137482 † Current address: Department of Microbial Infection and Immunity, Pelotonia Institute for Immuno-Oncology, Ohio State University Comprehensive Cancer Center, The Ohio State University, Columbus, OH 43201, USA. ‡ Current address: Department of Neurology, Division of Movement Disorders, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02115, USA. Abstract: Epstein–Barr virus (EBV) is etiologically associated with a number of malignant and non- malignant conditions. Thus, a prophylactic vaccine against this virus could help to reduce the burden of many EBV-associated diseases. Previously, we reported that an EBV virus-like particle (VLP) vaccine was highly immunogenic and produced a strong humoral response in mice. However, since EBV does not infect mice, the efficacy of the VLP in preventing EBV infection could not be addressed. Here we examined, for the first time, the efficacy of the EBV-VLP vaccine using a novel rabbit model of EBV infection. Animals vaccinated with two doses of VLP elicited higher antibody responses to total EBV antigens compared to animals receiving one dose. Vaccinated animals also elicited both IgM and IgG to EBV-specific antigens, VCA and EBNA1. Analysis of peripheral blood and spleen for EBV copy number indicated that the viral load in both of these compartments was lower in animals receiving a 2-dose vaccine. However, the VLP vaccine was ineffective in preventing EBV infection. With several other EBV vaccine candidates currently at various stages of development and testing, we believe that the rabbit model of EBV infection could be a great platform for evaluating potential candidates. Keywords: EBV; vaccine; VLP; rabbits; booster dose; immune response 1. Introduction Epstein–Barr virus (EBV), also known as human herpesvirus 4, is an oncogenic virus infecting about 90% of the human population. Primary EBV infection typically occurs early in childhood and establishes lifelong latency in memory B cells without triggering any symptomatic disease [1,2]. However, this harmless image of EBV infection contradicts its factual pathological potential. The subtle balance of virus-host interaction can be disturbed in several ways, which can lead to a range of diseases, including infectious mononucleo- sis [3,4], multiple sclerosis [5–8], post-transplant lymphoproliferative disease [9,10], and a number of malignancies of B lymphocyte and epithelial cell origin [11,12]. It is esti- mated that more than 250,000 cases of cancer are annually attributed to EBV [13,14]. In immunocompromised individuals, EBV is an important contributing factor to the overall morbidity and mortality. For example, patients who acquire primary EBV infection fol- lowing transplantation are at increased risk of developing EBV-associated malignancies. Thus, a prophylactic vaccine could have a major impact on reducing the burden of not only Vaccines 2023, 11, 540. https://doi.org/10.3390/vaccines11030540 https://www.mdpi.com/journal/vaccines