Abstract:
Asian elephants are an endangered species facing many threats, including severe hemorrhagic disease
(HD) caused by the elephant endotheliotropic herpesvirus (EEHV). EEHV-HD is the leading cause of death
in captive juvenile Asian elephants in North America and Europe, and also affects elephants in their natural
range countries. Significant challenges exist for successful treatment of EEHV-HD, which include
timely recognition of disease onset and limited availability of highly effective treatment options. To
address this problem, our goal is to prevent lethal disease in young elephants by developing a vaccine
that elicits robust and durable humoral and cell-mediated immunity against EEHV. EEHV glycoprotein
B (gB) is a major target for cellular and humoral immunity in elephants previously exposed to EEHV.
Therefore, we generated a vaccine containing recombinant EEHV1A gB together with a liposome formulated
TLR-4 and saponin combination adjuvant (SLA-LSQ). CD-1 mice that received one or two vaccinations
with the vaccine elicited significant anti-gB antibody and polyfunctional CD4+ and CD8+ T cell
responses, while no adverse effects of vaccination were observed. Overall, our findings demonstrate that
an adjuvanted gB protein subunit vaccine stimulates robust humoral and cell-mediated immune
responses and supports its potential use in elephants.
