KOALAS HOLD KEY TO VACCINE TRIAL
News source: The Courier-Mail, July 13 2005
By: Brendan O'Malley
CUDDLY koalas could hold the key to treating one of the most common sexually transmitted diseases in humans.
Scientists at the Queensland University of Technology made the unusual link while searching for a vaccine against chlamydia, a devastating disease in koalas.
The disease is also one of the most common sexually transmitted illnesses in humans and is responsible for up to 10 percent of infertility in women.
Professor Peter Timms, from QUT's Institute of Health and Biomedical Innovation, said the incidence of chlamydia was rising despite more people practicing safe sex because of AIDS.
He said reported cases were increasing at an estimated 20 percent a year but there was still no human vaccine.
"By studying chlamydial disease in koalas as well as in humans, we hope to understand how this tiny bug can cause so many nasty diseases and how to develop a vaccine for use in humans," he said.
"We are getting closer to discovering a chlamydia vaccine for koalas and hope to have a vaccine ready for (phase one or preliminary) human trials within a few short years."
Professor Timms said only a handful of other teams around the world had managed to get treatments to the phase one stage despite interest from big pharmaceutical companies.
That was because humans could be infected with any of 16 types of the chlamydia bacterium, which meant a vaccine or drug might work on some types but not others.
His team side-stepped the problem by using advances in DNA sequencing to compare human chlamydia types with those in koalas, something which was not possible for researchers outside Australia.
"Koalas are actually affected in similar ways and also get other human diseases like glaucoma, so we can test something in koalas and it should apply in humans," he said.
"What we did was to look at the similarities between the gene sequences and targeted a vaccine against those regions.
"We used an approach where we took the whole genome, chopped it into pieces and used ones which would work in a vaccine.
"We can't say which pieces, but some of the ones which popped out were not what you would expect from theory."
The QUT team was working with animal hospitals including Australia Zoo on the Sunshine Coast, where veterinarian Dr Jon Hangar treated many koalas for chlamydia.
"It is a very significant cause of infertility, urinary tract infections and inflammation in the lining of the eye that can eventually lead to blindness," Dr Hangar said.
He said the zoo's treatment success rate was currently less than 50 percent, but he hoped the QUT research would help them predict which koalas were more likely to respond to treatment.
Professor Timms said his IHBI team was also making good progress with an improved diagnostic test for women at risk of chlamydia.
"At the moment, it is difficult to detect the infection in women where it can remain as a silent infection for years, eventually resulting in infertility," he said.
"Women can have it for a long time and not know it until they find out they're infertile, so detection is vital."