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

The vaccine, produced by an international scientific group, is designed to prevent the severe disease caused by elephant endotheliotropic herpesvirus (EEHV), which is currently a primary cause of death in juvenile Asian elephants.

In tests that involved adult elephants at Chester Zoo, the vaccine was found to be harmless and, importantly, to activate components of the body's defenses that assists in fighting viruses.

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

It is hoped that the result of this pioneering trial will pave the way to preventing the deaths of young elephants from the harmful condition caused by this virus.

Devastating Impact

EEHV has had a particularly devastating effect in captive environments. At one facility 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 certain sanctuaries and elephant orphanages.

It causes a haemorrhagic disease - uncontrolled bleeding that can be fatal within 24 hours. It leads to death in more than 80% of cases in young elephants.

Understanding the Threat

Why EEHV can be so lethal is still unknown. Numerous adult elephants host the virus - apparently with no negative impact on their well-being. But it is thought that juvenile elephants are particularly vulnerable when they are being weaned, and when the protective defenses from the mother's milk decrease.

At this stage, a young elephant's natural defenses is in a delicate balance and it can become overpowered. "It may lead to really severe illness," a lead conservation scientist explained.

"It does affect wild elephants, but we lack an exact number of how many fatalities in overall 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 "scaffold". Basically, the basic structure of this vaccine is identical to one commonly employed to immunise elephants against a virus called a related virus.

The scientists seeded this immunization framework with components from EEHV - harmless parts of the virus that the elephant's defense system might identify and respond to.

In a pioneering experiment, the team evaluated the novel vaccine in three healthy, adult elephants at the zoo, then examined blood samples from the innoculated animals.

The lead researcher commented that the findings, released in a research publication, were "more successful than anticipated".

"They showed, clearly that the vaccine was able to stimulate the production of immune cells, that are crucial to combating viral infections."

Future Steps

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

The present immunization involves four shots to be administered, so another aim is to determine if the same effective dose can be given in a more straightforward way - possibly with fewer jabs.

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

The project lead continued: "We believe this is a significant advancement, and not necessarily only for the elephants, but because it additionally demonstrates that you can design and apply vaccines to assist endangered species."