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Scientists have achieved a major advance in creating a novel vaccine to combat a deadly virus that targets juvenile elephants.

The inoculation, produced by an international scientific group, is designed to stop the serious disease caused by elephant endotheliotropic herpesvirus (EEHV), which is currently a leading cause of death in young Asian elephants.

In trials that involved mature elephants at Chester Zoo, the vaccine was found to be safe and, importantly, to stimulate components of the body's defenses that helps combating viruses.

Prof Falko Steinbach described this as "a landmark moment in our efforts to safeguard Asian elephants".

It is anticipated that the result of this pioneering trial will pave the way to preventing the fatalities of young elephants from the harmful disease caused by this virus.

Devastating Impact

EEHV has had a especially destructive impact in zoos. At one facility by itself, seven baby elephants have died to it over the last decade. It has also been found in wild elephant herds and in some sanctuaries and elephant orphanages.

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

Understanding the Threat

Why EEHV can be so lethal is still unknown. Numerous mature elephants host the virus - seemingly with no negative impact on their health. But it is believed that juvenile elephants are especially vulnerable when they are being weaned, and when the immune-boosting antibodies from the mother's milk decrease.

At this stage, a young elephant's immune system is in a delicate state and it can become overpowered. "It may lead to really severe disease," Dr Katie Edwards stated.

"It impacts elephants in nature, but we don't have an precise count of how many deaths in overall it has resulted in. For elephants in captivity however, there have been over a hundred deaths."

Vaccine Development

The research team, headed by veterinary scientists, created the new vaccine using a proven "framework". Essentially, the basic structure of this vaccine is identical to one commonly employed to vaccinate elephants against a virus called cowpox.

The researchers seeded this vaccine structure with proteins from EEHV - non-infectious parts of the virus that the animal's immune system might recognise and respond to.

In a world-first trial, the team evaluated the new vaccine in several fit, mature elephants at the zoo, then analysed blood samples from the vaccinated animals.

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

"They showed, unequivocally that the vaccine was effective to activate the generation of immune cells, that are vital to combating viral infections."

Next Phases

The next step for the researchers is to test the vaccine in younger elephants, which are the animals most at risk to serious illness.

The present immunization involves four shots to be given, so an additional objective is to work out if the same protective amount can be provided in a simpler way - perhaps with fewer jabs.

Dr Edwards clarified: "In the end we want to employ this vaccine in the elephants that are at risk, so we need to make sure that we can deliver it to where it's needed."

Prof Steinbach continued: "We think this is a major step forward, and not necessarily solely for the elephants, but because it also demonstrates that you can design and apply vaccines to assist endangered species."