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Researchers have achieved a major advance in developing a novel immunization to combat a deadly virus that targets juvenile elephants.

The vaccine, developed by an international research team, aims to prevent the serious disease caused by EEHV, which is presently a leading cause of death in juvenile Asian elephants.

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

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

It is anticipated that the result of this pioneering trial will open the door to averting the fatalities of juvenile elephants from the dangerous disease caused by this virus.

Devastating Impact

EEHV has had a particularly devastating effect in captive environments. At Chester Zoo alone, seven young elephants have succumbed to it over the past ten years. It has also been found in natural populations and in some sanctuaries and elephant orphanages.

It causes a haemorrhagic disease - unchecked bleeding that can be fatal within a day. It leads to death in more than 80% of instances in young elephants.

Understanding the Threat

Why EEHV can be so dangerous is remains unknown. Many mature elephants carry the virus - seemingly with no adverse effects on their well-being. But it is believed that young calves are particularly susceptible when they are being transitioned from milk, and when the immune-boosting antibodies from the mother's milk decrease.

At this stage, a calf's immune system is in a precarious state and it can become overwhelmed. "It may lead to extremely serious disease," Dr Katie Edwards stated.

"It impacts elephants in nature, but we don't have an precise count of how many fatalities in overall it has caused. For elephants in captivity however, there have been more than 100 deaths."

Vaccine Development

The scientific group, led by animal health experts, created the novel vaccine using a tried and tested "scaffold". Essentially, 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 vaccine structure with proteins from EEHV - non-infectious parts of the virus that the elephant's immune system might recognise and respond to.

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

Prof Steinbach stated that the findings, released 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 fighting viral infections."

Future Steps

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

The current vaccination involves multiple injections to be given, so another aim is to work out if the equivalent effective amount can be provided in a simpler way - perhaps with less injections.

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

The project lead added: "We believe this is a major step forward, and not necessarily only for the elephants, but because it also shows that you can develop and use vaccines to help endangered species."