Elephant endotheliotropic herpesvirus gB-specific antibody levels in sera of Asian elephants (Elephas maximus) in Japanese zoos.

Prevalence of elephant endotheliotropic herpesvirus (EEHV) infections in Asian elephants in Japan was assessed by determination of EEHV gB specific antibody levels. Among 28 healthy Asian (sub) adult elephants from 11 zoos, 27 animals exhibited intermediate to high antibody levels. Like elsewhere worldwide, this suggested exposure of Asian elephants in Japan to at least one EEHV (sub) species.

The EEHV1A gH/gL complex elicits humoral and cell-mediated immune responses in mice.

Elephant endotheliotropic herpesvirus (EEHV) causes lethal hemorrhagic disease (HD) in Asian and African elephants. Although rapid detection of viremia and supportive treatments may improve survival rates, an effective vaccine would mitigate the devastating effects of this virus. In elephants, chronic infection with EEHV leads to adaptive immunity against glycoproteins gB and gH/gL, the core entry machinery for most herpesviruses.

Low gH/gL (Sub)Species-Specific Antibody Levels Indicate Elephants at Risk of Fatal Elephant Endotheliotropic Herpesvirus Hemorrhagic Disease.

Elephant endotheliotropic herpesviruses (EEHVs), of which eleven (sub)species are currently distinguished, infect either Asian () or African elephants ( species). While all adult elephants are latently infected with at least one EEHV (sub)species, young elephants, specifically those with low to non-detectable EEHV-specific antibody levels, may develop fatal hemorrhagic disease (EEHV-HD) upon infection. However, animals with high antibody levels against EEHV(1A) gB, an immunodominant antigen recognized by antibodies elicited against multiple (sub)species, may also occasionally succumb to EEHV-HD.

EEHV1A glycoprotein B subunit vaccine elicits humoral and cell-mediated immune responses in mice.

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.

Young elephants in a large herd maintain high levels of elephant endotheliotropic herpesvirus-specific antibodies and do not succumb to fatal haemorrhagic disease.

Elephant endotheliotropic herpesviruses (EEHVs) have co-existed with elephants for millions of years, yet may cause fatal haemorrhagic disease (EEHV-HD), typically in elephants between 1 and 10 years of age. EEHV is omnipresent in (sub)adult elephants, and young elephants with low EEHV-specific antibody levels are at risk for EEHV-HD, suggesting that fatal disease may occur due to an insufficiently controlled primary infection. To further address this hypothesis, sera of three large elephant cohorts were subjected to a multiple EEHV species ELISA: (I) 96 Asian elephants between 0 and 57 years, including 13 EEHV-HD fatalities, from European zoo herds typically sized five to six elephants, (II) a herd of 64 orphaned elephants aged 0-15 years at the Elephant Transit Home in Sri Lanka and (III) 31 elephants aged 8-63 years, part of a large herd of 93 elephants at Pinnawala Elephant Orphanage, Sri Lanka.