A bivalent EBV vaccine induces neutralizing antibodies that block B and epithelial cell infection and confer immunity in humanized mice

ABSTRACT

Epstein Barr virus (EBV) is the major cause of infectious mononucleosis and is associated with several human cancers. Despite its prevalence and major impact on human health, there are currently no specific vaccines or treatments. Four viral glycoproteins, gp 350 and gH/gL/gp42 mediate entry into the major sites of viral replication, B cells and epithelial cells. Here, we designed a nanoparticle vaccine displaying these proteins and show that it elicits potent neutralizing antibodies that protect against infection in vivo. Based on structural analyses, we designed single chain gH/gL and gH/gL/gp42 proteins that were each fused to bacterial ferritin to form a self-assembling nanoparticles. X-ray crystallographic analysis revealed that single chain gH/gL and gH/gL/gp42 adopted a similar conformation to the wild type proteins, and the protein spikes were observed by electron microscopy. Single chain gH/gL or gH/gL/gp42 nanoparticle vaccines were constructed to ensure product homogeneity needed for clinical development. These vaccines elicited neutralizing antibodies in mice, ferrets, and non-human primates that inhibited EBV entry into both B cells and epithelial cells. When mixed with a previously reported gp350 nanoparticle vaccine, gp350D₁₂₃, no immune competition was observed. To confirm its efficacy in vivo, humanized mice were challenged with EBV after passive transfer of IgG from mice vaccinated with control, gH/gL/gp42+gp350D₁₂₃ or gH/gL+gp350D₁₂₃ nanoparticles. While all control animals (6/6) were infected, only one mouse in each vaccine group that received immune IgG had transient low level viremia (1/6). Furthermore, no EBV lymphomas were detected in immune animals in contrast to non-immune controls. This bivalent EBV nanoparticle vaccine represents a promising candidate to prevent EBV infection and EBV-related malignancies in humans.