Two fruit bats hanging from a gum tree branch.

CSIRO is undertaking research to help control the spread of viruses from bats.

CSIRO’s bat pack sheds light on deadly viruses

Nicknamed the ‘bat pack’, CSIRO's bat virology team is focused on gaining a better understanding of bat immunology and bat virus-host interaction, to assist in developing strategies to help control or prevent viruses which spread from bats to other animals and people.

  • 17 December 2012

 

The bat pack

The bat virology team, located at the Australian Animal Health Laboratory (AAHL) in Geelong Victoria, includes 25 scientists dedicated to unravelling the mysteries associated with bats and the relationship they have with the viruses they carry.

Major disease outbreaks over the past two decades that have been found to have originated in bats include Hendra, Nipah, Ebola, Marburg, Melaka and SARS. Hendra and Nipah are among the deadliest animal viruses as they are fatal in around 50-70 per cent of people and animals infected.

Threat of the zoonotic

Viral diseases that spread from animals to humans – known as zoonotic viruses – are proving to be highly unpredictable both in terms of host range and speed of spread so they pose the greatest threat.

While some of our most deadly zoonotic viruses originate in bats, bats are merely carriers of the virus and rarely develop the disease themselves. One aspect of research is focusing on how bats are able to tolerate the viruses that are fatal in livestock and people.

Bats have lived in colonies in undisturbed habitats for millions of years however, as we invade those habitats we increase the risk of viruses that live in harmony with the bats, spilling over to new hosts.

The spill-over effect

The SARS epidemic of 2003 is a perfect example of a previously unknown virus causing worldwide chaos as it spread from China to Hong Kong to as far as Canada. Scientists believe that a SARS-like virus was dormant in bats for some time before a chance mutation occurred in another host, the civet cat, almost certainly infected from bats in a live animal market. This wild cat is commonly consumed as food in Southern China and other Asian countries and it is believed that the trading and consumption of this animal species is how the SARS epidemic started. 

These types of chance events demonstrate the ability of a virus to mutate and become deadly for existing and new hosts, known as ‘host switching’. Our ongoing research into bat-borne viruses and further understanding of host switching, is where we believe the answers lie in being able to predict the future spread of new and emerging infectious diseases.

While in many cases host-switching events go unnoticed, as no disease develops in the new host, in other situations the virus adapts to the new species and causes severe illness or death.

Staying a step ahead

As the world continues to change, it is expected that more currently unknown bat viruses will emerge. The challenge is to get ahead of the viruses before they are given the opportunity to jump into new hosts. 

A better understanding of virus-bat interactions will help lead to faster, more sensitive and novel surveillance tools that may radically change the risk management of emerging infectious diseases within Australia and globally. 

That will mean that we can progress from just responding when an outbreak occurs, to putting pre-emergence surveillance and prevention strategies in place. Similar to a weather or earthquake forecast, if we can develop a system to provide virus forecasts, we will be far more prepared and capable of containing the spread of disease.

The more we can learn about bat-borne viruses, the better chance we have of identifying strategies to better control them such as developing anti-virals and vaccines to help protect people, our livestock industry and our export trade from the threat of current and emerging animal diseases. Significant progress has already been made with the CSIRO-developed Hendra virus vaccine for horses.

Ongoing research will help enhance Australia’s biosecurity and limit the wide ranging impacts that a new disease can have in our closely interconnected and highly mobile world.

Disease outbreaks

AAHL has helped detect and characterise many new viral diseases including:

  • Hendra virus - First isolated in Queensland in 1994 after it spread from bats, killing 14 horses and a horse trainer, Hendra has since re-emerged several times and in 2011 a spike in spill-over events in Queensland and New South Wales resulted in the death of 23 horses and the first evidence of the virus in a dog.
  • Nipah virus - Closely related to the Hendra virus, Nipah was discovered in Malaysia in 1998, when it spread from bats to pigs to humans, killing more than 100 people and resulting in the culling of more than a million pigs in order to control the spread of the virus. Since then, and as recently as 2011, it has caused further outbreaks, in Bangladesh and India.
  • Australian bat lyssavirus - This rabies-like virus, discovered in 1996, has been found in flying foxes and bats throughout Australia and has caused illness and death in humans.
  • Melaka virus - The virus was identified in Malaysia in 2006 as the cause of respiratory tract illness in humans.
  • Cedar virus - Scientists at AAHL recently discovered a new bat virus in Queensland called Cedar. While it’s a close relative of the deadly Hendra and Nipah viruses, the surprising difference is that Cedar virus doesn’t cause illness in several animal species normally susceptible to Hendra and Nipah. This tantalising difference may help scientists narrow down what it is about the genetic makeup of viruses like Hendra and Nipah that leads to disease and death.

Read more about our research at the Australian Animal Health Laboratory.