Dry behind the rears

A team from Queensland University of Technology's Institute of Health and Biomedical Innovation, led by well-known microbiologists Professor Peter Timms and Professor Ken Beagely, is about to begin a small trial of a combination vaccine against Chlamydia in koalas, a disease endemic to the population which is increasingly being exacerbated by their biggest foe, habitat destruction.

That a potential vaccine is finally in the trial phase is of course good news - that the scientists involved are finding it difficult to secure future funding is not.

The research that has led the group to the its current position of being able to test a koala vaccine has been largely funded by those good people at the NHMRC, as well as some help from Lone Pine Koala Sanctuary.

But Timms is still on the lookout for either a corporation or individuals who wouldn't mind helping out in the attempt to save one of our iconic species from infertility and those sore little wet bottoms.

Timms has been studying the various permutations of Chlamydia and different species that carry it for many years. It has of course long been known that one strain, C. trachomatis, is the leading cause of preventable blindness in humans in the world.

Trachoma is estimated to affect about 500 million people, mainly in the developing world, and of course our own indigenous population, a fact many are wont to ignore.

It has also now known that another common strain, C. pneumoniae, is linked to heart disease and stroke in humans as well as its role in respiratory disease, a breakthrough Timms was at the forefront of.

Many research teams world-wide are working on developing treatments and potential vaccines for Chlamydia in humans, including Timms' own team, and these human studies are slowly progressing towards clinical trials in the next five years or so.

For the poor old koala, however, funds seem to be a bit scarce. Timms' team is the first in the world to go into early stage trials for a koala-specific vaccine, which will take place later this year in a captive koala population at Lone Pine Koala Sanctuary in Brisbane.

While the strains of Chlamydia that affect humans and koalas are different, there is a lot to learn from one that will help the other, Timms says.

In humans C. trachomatis, is the culprit, causing urinary tract infections that can lead to pelvic inflammatory disease and thus to reproductive complications and infertility.

In koalas it is C. pecorum, also sexually transmitted and causing genital infections. As the infection ascends up the urinary tract it infects the bladder and causes the most obvious sign of the disease in koalas, 'wet bottom' or 'dirty tail'.

"You'd be surprised at how similar it is to human chlamydial disease," Timms says. "Using a mouse model of the human sexually transmitted disease we've identified some vaccine antigens so we then can take the parallel one across and make a koala equivalent vaccine."

The team is developing a combination vaccine, which Timms says no one has done before.

"Instead of just using one particular protein we are using a combination of two or three. It will be a combination of surface proteins so we will be using the major outer membrane protein, which is fairly traditional, but we have also identified proteins that are inside the Chlamydia that you would not normally think would be useful for vaccine targets, but seem to be.

"This way we can target both arms of the immune response, the one that produces antibodies but also the one that produces cell mediated immunity. This is a relatively new approach for producing chlamydial vaccines.

"That's interesting in its own right, the idea of combining the two of them together. We are hopeful that that will produce a better vaccine down the line. It makes sense, but will it work? We'll see."

While estimates vary about the prevalence of Chlamydia infection among wild populations, Timms puts it has high as 70 per cent, although only 10 to 15 per cent show clinical signs of disease.

"But if you then take a population where we are knocking all their trees down around them, they become stressed, and what you see then is that as many as 50 per cent will show signs of disease. Whereas if they are well maintained, Chlamydia will be there but it is more of a background infection that is not so obvious."

Timms has funding for the initial stage of the trial but he's at a bit of a loss after that. He's hoping for the best, however, and in the meantime is continuing with studies of both a vaccine for young women and a diagnostic test that is in development through the CRC for Diagnostics, which has just been wound up after five years.

"We are trying to develop a diagnostic assay that would be useful for women to see if they've got a chronic infection and we think we've got something," he says.

"We are already in the process of liaising with two or three companies around the world that already make Chlamydia tests and they would hopefully add this to their range of tests.

"This is for women with low-grade, smouldering infections that they don't know they've got. If they knew it they could do something about it before it ended up being a blockage and ultimately leading to infertility."

The team at the IHBI is also working on developing a murine model for a vaccine for chlamydial-caused heart disease.

In the meantime, the work continues to help the koala. The first phase of the trial is expected to run for between six and 12 months, with initial results expected quite early.

"We will continue to monitor the koalas for 12 months to determine how long the vaccine stimulates an immune response in the koalas and whether or not a booster shot is required."