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Researchers have achieved a major advance in developing a new vaccine to combat a deadly virus that affects juvenile elephants.

The inoculation, produced by an international research team, aims to prevent the serious disease caused by EEHV, which is currently a primary cause of death in juvenile Asian elephants.

In trials that involved adult elephants at Chester Zoo, the vaccine was found to be safe and, importantly, to stimulate part of the body's defenses that assists in fighting viruses.

Prof Falko Steinbach called this as "a landmark moment in our work to protect Asian elephants".

It is hoped that the result of this first-of-its-kind trial will pave the way to averting the deaths of juvenile elephants from the harmful disease caused by this virus.

Severe Consequences

EEHV has had a particularly devastating effect in captive environments. At Chester Zoo alone, multiple young elephants have died to it over the last decade. It has additionally been found in natural populations and in certain refuges and care centers.

It causes a haemorrhagic disease - uncontrolled hemorrhaging that can be fatal within 24 hours. It results in death in over eighty percent of cases in young elephants.

Understanding the Threat

Why EEHV can be so lethal is still unclear. Numerous adult elephants host the virus - seemingly with no adverse effects on their health. But it is believed that young elephants are especially vulnerable when they are being transitioned from milk, and when the immune-boosting defenses from the mother's milk decline.

At this phase, a calf's immune system is in a delicate state and it can become overwhelmed. "It can cause extremely serious disease," a lead conservation scientist explained.

"It does affect wild elephants, but we lack an exact number of how many deaths in total it has resulted in. For elephants in captivity though, there have been more than 100 deaths."

Vaccine Development

The research team, led by veterinary scientists, created the new vaccine using a proven "scaffold". Basically, the core design of this vaccine is identical to one commonly employed to vaccinate elephants against a virus called a related virus.

The scientists incorporated this vaccine structure with components from EEHV - harmless parts of the virus that the animal's immune system might identify and respond to.

In a pioneering experiment, the team evaluated the new vaccine in three fit, adult elephants at the zoo, then analysed blood tests from the innoculated animals.

Prof Steinbach commented that the findings, published in a research publication, were "more successful than anticipated".

"They showed, unequivocally that the vaccine was able to stimulate the generation of immune cells, that are crucial to combating virus attacks."

Next Phases

The subsequent phase for the scientists is to try the vaccine in younger elephants, which are the animals most at risk to severe disease.

The current vaccination involves four injections to be given, so another aim is to work out if the equivalent protective amount can be given in a more straightforward way - perhaps with less injections.

Dr Edwards explained: "Ultimately we aim to use this vaccine in the elephants that are in danger, so we want to ensure that we can get it to where it's necessary."

Prof Steinbach continued: "We think this is a significant advancement, and not just solely for the elephants, but because it additionally demonstrates that you can develop and use vaccines to help endangered species."