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Scientists have made a breakthrough in developing a new vaccine to combat a fatal virus that targets juvenile elephants.

The vaccine, produced by an global research team, is designed to stop the severe disease caused by EEHV, which is currently a primary cause of death in young Asian elephants.

In trials that included adult elephants at Chester Zoo, the vaccine was found to be harmless and, crucially, to activate components of the immune system that assists in combating viruses.

A lead scientist described this as "a landmark moment in our work to protect Asian elephants".

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

Severe Consequences

EEHV has had a particularly destructive effect in zoos. At Chester Zoo by itself, seven young elephants have succumbed to it over the past ten years. It has also been detected in wild elephant herds and in some sanctuaries and care centers.

It causes a haemorrhagic disease - uncontrolled hemorrhaging that can be fatal within 24 hours. It results in death in more than 80% of cases in juvenile elephants.

Understanding the Threat

Why EEHV can be so lethal is remains unknown. Many adult elephants carry the virus - seemingly with no negative impact on their health. But it is believed that young calves are particularly vulnerable when they are being weaned, and when the protective antibodies from the mother's milk decline.

At this stage, a young elephant's immune system is in a delicate state and it can become overwhelmed. "It can cause extremely serious illness," a lead conservation scientist explained.

"It does affect elephants in nature, but we lack an precise count of how many deaths in total it has resulted in. For elephants in captivity however, there have been over a hundred deaths."

Vaccine Development

The research team, led by veterinary scientists, developed the novel vaccine using a proven "framework". Basically, the core design of this vaccine is identical to one commonly employed to vaccinate elephants against a virus called cowpox.

The scientists incorporated this vaccine structure with components from EEHV - non-infectious bits of the virus that the elephant's defense system might identify and respond to.

In a world-first experiment, the team tested the new vaccine in three fit, adult elephants at Chester Zoo, then examined blood tests from the innoculated animals.

The lead researcher commented that the findings, published in a scientific journal, were "more successful than anticipated".

"They showed, unequivocally that the vaccine was able to activate the generation of T cells, that are vital to combating virus attacks."

Future Steps

The subsequent phase for the researchers is to try the vaccine in younger elephants, which are the animals most at risk to serious illness.

The present immunization involves four injections to be administered, so an additional objective is to determine if the equivalent protective dose can be given in a simpler way - possibly with less injections.

The conservation scientist explained: "In the end we want to employ this vaccine in the elephants that are at risk, so we want to make sure that we can deliver it to where it's necessary."

The project lead added: "We think this is a significant step forward, and not necessarily only for the elephants, but because it additionally demonstrates that you can design and use vaccines to assist endangered species."