Researchers have determined how antibodies induced by the Epstein-Barr virus (EBV) block the infection of laboratory-grown cells. Using the information, they developed novel vaccine candidates that elicited powerful anti-EBV antibody responses that blocked the infection of cells involved in EBV-associated cancers.
Currently, there is no approved vaccine for EBV. The virus is associated with nasopharyngeal and gastric cancers, as well as Burkitt and Hodgkin lymphomas. Approximately 200,000 cases of EBV-associated cancers occur each year around the world, resulting in 140,000 deaths.
Previous efforts to develop a vaccine focused on gp350, a viral surface protein used by EBV to enter B cells. But in addition to B cells, EBV infects epithelial cells lining the mouth and upper throat.
The scientists developed two vaccine candidates, one designed to elicit antibodies to gH/gL on epithelial cells and one that included gH/gL and the viral protein gp42. They tested the vaccines in mice and monkeys, and in both models, each vaccine induced antibodies that obstructed epithelial-cell fusion. The vaccine with gp42 resulted in stronger B-cell fusion inhibitory antibodies than the one containing gH/gL alone.
Unlike the gp350-candidate vaccine, which protects only B cells from infection, the current candidate vaccines elicited antibodies that could prevent EBV from fusing with both epithelial cells and B cells, potentially providing protection regardless of cell type. The team now plans to further develop one of the vaccines with a view toward human trials.
Source: National Institutes of Health, April 9, 2019