Australasian Science: Australia's authority on science since 1938

Hendra Antibodies Found in African Bats

By Stephen Luntz

The discovery of antibodies capable of neutralising the Hendra and Nipah viruses in African bats has overturned ideas about how the viruses spread.

Hendra and Nipah viruses, sometimes considered one disease, are carried by fruit bats. While there is no record of the bats getting sick, Hendra can be transmitted to horses and then to people, while Nipah can be transmitted directly to people. In both cases the viruses can be fatal.

It had been thought that the viruses could only survive in large interconnected bat populations. This would mean that if either disease died out in one population, antibody resistance would drop and this would allow re­infection to occur from a separate colony. However, a study of fruit bats on isolated islands off the coast of Africa, published in PLoS One, detected the widespread presence of antibodies capable of neutralising either disease.

While no genetic material from either virus has been detected, Mr Gary Crameri of the Australian Animal Health Laboratory says the antibodies would only be present if the bats had been exposed to a disease so similar to Hendra and Nipah that it might be considered a variety of the same disease.

“Hendra and Nipah viruses cause fatal infections in humans, but we currently understand very little about how the viruses are transmitted from bats to other animals or people,” says Cambridge University PhD student Alison Peel. “To understand what the risk factors for these ‘spill-overs’ are, it is crucial to understand how viruses are maintained in bat populations. The ability to study these viruses within an isolated bat colony has given us new insight into these processes.”

Peel suggests that the discovery may assist in learning why two viruses that appear to have existed in bat populations for long periods of time have only started spilling over to humans in the past 20 years.

Crameri says no cases of Hendra-like viruses have been observed in humans in the area, but gaining accurate information and samples from Africa can be a challenge.

The researchers were not actually looking for diseases normally associated with Australia and South-East Asia. Instead, Cambridge researchers were exploring the theory that African bats spread Ebola virus, and contacted the AAHL for their known expertise in virus identification.

A further puzzling feature of the discovery is that the African fruit bats in which the antibodies were found are very different from the flying fox species that carry the disease in Australia and Asia. The genetic isolation of the animals indicates that the bats have not interacted with related species for a long time, and Crameri says at the moment it is not possible to explain how such viruses could persist in this environment “unless the bats’ immune system is quite different from humans”.