Feature: Battling Hendra virus

Read part I: Biosecurity and animal-borne viruses

“We basically want to understand why bats have become the ideal reservoir for a variety of different viruses that affect humans and livestock, and what triggers the spill over and subsequent infection in other species,” says CSIRO’s Dr Lin-Fa Wang.

The initial challenge was that virtually nothing was known about bats except some basic physiology surrounding their eco-location mechanisms.

“It was ground zero in terms of the knowledge and reagents needed to start answering some basic questions such as why don’t the bats themselves get sick. So a few years ago we faced the choice of just continuing to study the viruses like Hendra without studying their natural reservoirs, or starting from scratch and studying the hosts as well.”

Wang’s location at the AAHL, with the world’s largest Physical Containment Level 4 (PC 4) facility, made this choice a little easier, particularly with the sort of live virus experiments involved.

Also, Australia, and Wang’s group in particular, are leading the field internationally. “So we made the decision that this was an important area and that we were probably the best placed for success.”

The group has since morphed from doing pure virology and discovery to becoming world experts in bat biology, from bat genomics to bat proteomics to bat immunology. It has been demanding time, and now about half the group work solely on bat immunology.

“The first few years was really about getting together our research tool box: identifying all the genes; doing RT-PCR; making antibodies, proteins and even cell lines. We are now moving from that phase into trying to understand the disease pathogenesis and doing functional studies to better understand the bat innate immune responses.”

At the Lorne Infection and Immunity meeting, Wang described two of his group’s current directions that span from discovery to clinical aspects of their work.

Firstly, CSIRO has worked closely over the past few years with the Queensland and Federal governments in the fight against the deadly Hendra virus, particularly with another human death in 2009 and a new outbreak in horses in early 2010.

“We are working hard to develop a vaccine for horses, and early immunisation studies with a recombinant viral antigen are showing promising results against infection in small animal models challenged with HeV.

It is pretty clear, in the Australian setting at least, that there is no bat-to-human transmission, and all human cases so far have involved close contact with sick horses,” Wang explains.

Vaccinating horses in high-risk regions, such as Queensland, is therefore considered the best way to prevent the viral jump from bats into other species, particularly as it seems that only a few individuals in a bat colony are to blame for the virus spilling over to infect horses, and predicting where and when this might occur is presently impossible.

“We are also working on a post-exposure therapeutic for human use, which is more practical and scientifically sensible than a vaccine approach. In collaboration with our colleagues in the USA, we have engineered several recombinant human monoclonal antibodies against surface proteins of HeV that seem successful at neutralising the live virus.”

This product is also going through animal trials and, in fact, was given to a mother and her daughter in a Brisbane hospital earlier this year during the 2010 outbreak.

Read part II: Biosecurity batman