An image of a large flying fox (Pteropus vampyrus). Australian flying foxes carry the deadly Hendra virus, but a new study testing a human antibody has shown success in protecting monkeys in a lab setting.
Credit: Wikimedia commons
WASHINGTON: A human antibody has been shown to protect infected monkeys from the potentially fatal consequences of Hendra, a bat-carried virus first discovered in Australia in 1994.
The latest outbreak of the virus has killed 20 horses in New South Wales and Queensland since June, but no humans. However four of the seven people who have contracted the disease have died.
The U.S.-led research, described this week in the journal Science Translational Medicine, was done at a highly protected lab in Montana, where 14 African green monkeys were injected with Hendra virus.
Twelve of the monkeys were then treated with a human antibody called m102.4, and they all survived while the untreated pair died.
"I think this is a very promising therapy, especially when you consider that it was still strong three days later," said lead author Thomas Geisbert of the University of Texas Medical Branch at Galveston.
"What's also interesting is that this antibody has strong activity against Nipah virus as well, which is extremely similar to Hendra."
Emergency use for infected humans
Earlier experiments on smaller animals have also shown efficacy from the antibody against Hendra virus.
After the U.S. study on monkeys concluded in 2010, the antibody was injected in a woman and her 12-year-old daughter in Australia last year as an emergency protection for exposure to Hendra.
While the two survived with no side effects from the treatment, scientists say more study needs to be done before the antibody can be used as a widespread remedy.
The Hendra virus, which kills about 60% of those it infects, is believed to spread to horses living in paddocks with fruit trees via half-chewed fruit, or through the ingestion of water and food contaminated by bats' droppings.
Human contraction
Horses can then spread it to humans, though experts say this is unlikely, and no person-to-person transmission cases have been documented.
"The most important thing to keep in mind when you have these outbreaks is that in general terms, there is no great risk to humans... Transmission to humans does not happen very readily," said John MacKenzie, an expert in infectious disease emergence at Curtin University in Western Australia.
He says the only people at risk would be those in direct contact with infected horses or bats, and even then there needs to be an open cut "which comes into contact with horse blood or nasal discharge."
Nipah virus a bigger concern?
However, Nipah virus, which emerged in 1998 in Malaysia and has been detected in Bangladesh and India, appears to infect humans more easily than Hendra and can be transmitted from person to person.
Nipah virus has infected 475 humans and killed 251 of them, according to the World Health Organization's latest data in 2008.
There is no licensed treatment or vaccine for either the Hendra and Nipah viruses. The fruit bats that carry the disease are found mainly in Australia but have also been tracked to parts of Africa, India, Pakistan, and the Philippines
