A human antibody has been shown to protect lab monkeys from the deadly bat-borne Hendra virus, US scientists say.

The Hendra virus has killed more than 20 horses in New South Wales and Queensland this year, but no humans.

The Hendra virus has killed more than 20 horses in New South Wales and Queensland this year. Credit:AFP

However four of the seven people ever to have contracted the disease have died.

The research, described 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.