An Asian elephant at the Houston Zoo in the US received the first mRNA vaccine against herpes, which the leading killer of Asian elephants calf in captivity.
Tess, a 40-year-old Asian elephant, was injected with the experimental vaccine at the Texas zoo in June, following a spate of juvenile deaths in zoos around the world due to the elephant endotheliotropic herpesvirus (EEHV).
Dr. Paul Ling, who researches herpes in humans at Baylor College of Medicine in Houston, developed the elephant mRNA vaccine, which is designed to boost the immunity of young elephants.
“When elephants are born, they have a tremendous amount of antibodies that they get from their mother,” he said. “When the female elephant gives birth, she probably already had this virus, so she gives protective antibodies to her baby, and it lasts for a certain period of time. Our vaccine is designed to give these young elephants enough immunity that they have lost over time.”
The mRNA vaccine is similar in design to the Covid-19 vaccines used in humans during the recent pandemic, and aims to prevent severe disease and death from EEHV in young Asian elephants.
The virus can cause a fatal hemorrhagic disease in Asian elephants, similar to the effects Ebola has on humans. Researchers believe it is passed on among Asian elephants through their trunks. First discovered in 1990 and scientifically described in 1999is the virus a major driver of Asian elephant deaths in captivity.
this month, two youths are dead of the virus at Dublin Zoo. Zoos in Chester, Melbourne and Zurich are among those that have lost several baby Asian elephants to the disease. In symptomatic elephants it has a death rate of about 70%.
While the virus has been recorded in wild populations and deaths recorded, experts are unsure how much impact it has on wild Asian elephants and whether a vaccination program would be practical. There are less than 50,000 of the species in the wild and they are threatened with extinction. Habitat loss, poaching and genetic isolation are all considered greater threats to their survival.
A spokesman for Chester Zoo said they thought the elephant herpes virus was a threat to the long-term survival of the Asian elephant, adding that reports of deaths were increasing in India, Nepal, Myanmar and Thailand.
“The only long-term solution to beating EEHV is to find a safe and effective vaccine, which will most likely be achieved through zoo-led research,” the spokesperson said.
“While the global conservation community has made significant strides in finding a viable vaccine, further work and time is needed before we have the answer we are all so desperately seeking – scientific confirmation that the vaccine is effective in preventing EEHV.”
Researchers are monitoring Tess’s health, and the Houston Zoo plans to vaccinate more Asian elephants later this year if no side effects are noted. The mRNA was developed in a partnership between the Houston Zoo, Baylor College of Medicine and the Dallas-based “de-extinction” company Colossal.
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