Progress has been made towards developing a vaccine for the Epstein-Barr virus, a herpesvirus that causes infectious mononucleosis and is associated with certain cancers.
By elucidating how antibodies block the Epstein-Barr virus (EBV) from infecting cells grown in the laboratory, researchers have developed two novel vaccine candidates. The vaccine candidates elicited potent antibody responses in animal models, and blocked the infection of cell types involved with EBV-associated cancers.
This research is significant as currently, there is no licensed vaccine for EBV. The virus is associated with several cancers (nasopharyngeal and gastric) of epithelial cells, as well as Burkitt and Hodgkin lymphomas which affect B cells. Worldwide, about 200,000 cases of EBV-associated cancers occur annually, resulting in 140,000 deaths.
The virus is also usually the culprit for infectious mononucleosis, or “mono”, which is spread through contact with saliva from another infected individual – hence why “mono” is also known as “the kissing disease”.
The research was led by NIH’s National Institute of Allergy and Infectious Diseases (NIAID), and is published in the journal Immunity. Jeffrey I. Cohen, M.D., and Wei Bu, Ph.D., both of NIAID, led the investigation.
Prior efforts to develop an EBV vaccine have been directed at targeting the viral surface protein that the virus uses to enter B cells (gp350). However, different approaches are needed as EBV also infects epithelial cells that line the mouth and upper throat.
Therefore, the NIAID team set out to define the contributions of virus-neutralizing antibodies, other than those directed at gp350 on B cells.
A complex called the gH/gL (pictured) was shown to play a major role in inhibiting EBV fusion with epithelial cells.
Consequently, two vaccine candidates were developed: one to elicit antibodies to gH/gL on epithelial cells, and another against both gH/gL and another viral protein (gp42). Vaccines were assessed in both mice and in non-human primates.
Each of the experimental vaccines potently inhibited epithelial cell fusion, in both animal models. The vaccine containing gp42 induced stronger B cell fusion inhibitory antibodies than the one containing gH/gL alone.
The authors note that the candidate vaccines elicited antibodies which could prevent EBV from fusing with both epithelial cells and B cells, and thus may provide protection independent of cell type.
The team say they plan to further develop one of the vaccine constructs, and hope to assess it in human trials.
This article has been republished from materials provided by the NIH/National Institute of Allergy and Infectious Diseases. Note: material may have been edited for length and content. For further information, please contact the cited source.
Bu. W., et al. (2019). Immunization with components of the viral fusion apparatus elicits antibodies that neutralize Epstein-Barr virus in B cells and epithelial cells. Immunity DOI: 10.1016/j.immuni.2019.03.010