Kiwis make TB discovery

By SIMON COLLINS

Auckland University scientists have found a compound that may provide a new cure for tuberculosis.

Laboratory tests in the United States have shown that the compound is effective against more than 50 strains of tuberculosis and other bacteria which are resistant to conventional antibiotics.

The US National Institutes of Health agreed last week to use state-of-the-art DNA testing to see how the compound actually works.

It could help save the lives of three million people who die from TB around the world each year.

Virulent forms of the disease, which are resistant to conventional drugs, are spreading in Asia, Africa, Europe and the US, partly because of the human immunodeficiency virus (HIV) epidemic. Thirty per cent of the world's population has been exposed to TB.

In New Zealand, TB cases fluctuate between 300 and 450 a year, with seven deaths in 2000, two in 2001 and four in 2002. Two-thirds of the patients in 2001 were immigrants, mostly from Asia and the Pacific.

Dr Brent Copp, a senior lecturer in chemistry who has been working on TB for seven years, said the anti-TB effect of the new compound was still "speculative" because it had yet to be tested in animals.

But it was already causing "excitement among people in the industry" following laboratory tests at the Southern Research Institute (SRI) in Alabama.

" SRI were incredibly excited ... because it is so potent and it shows activity against drug-resistant forms of tuberculosis from humans - against every strain they have ever isolated," he said.

"When a biologist tells you it's exciting, when they have been working in this area for 10 years and get excited, it's a really good idea to get excited too."

The compounds will now be tried on animals, with results due within six to nine months.

If successful, further trials on human TB patients could be "fast-tracked" under special US Food and Drug Administration rules for infectious diseases, and drugs could be on the market within five years.

"If they are active in animals, then it's a case of securing patent protection and really starting to crank up making hundreds of thousands of different analogues [varieties] to get the best example that we can," Dr Copp said.

Chemistry students Kerrie Austin and Timothy Chang, both 20, and Stephen McCracken, 21, have spent their holidays testing new varieties of the compound, using $4000 summer scholarships which aim to encourage students into post-graduate study in science.

An Auckland respiratory physician and tuberculosis specialist, Dr Adrian Hamilton, said only 1 per cent of New Zealand TB cases were resistant to all known drugs. But such cases accounted for up to 20 to 30 per cent of TB patients in some countries such as the Philippines, eastern Europe and parts of Russia.

"In New Zealand we get only one to three serious drug-resistant cases a year, but when they do happen it's a huge problem. It's an infectious disease and if someone else gets it from them you are on the verge of major trouble," he said.

"We are very hard pressed to come up with good treatment to give them. For years we have been saying there is no new drug on the horizon.

"So to have a new drug would be fantastic if it proves to be effective. It would have very important and major implications."

Dr Copp said the university got involved in TB by accident.

"We were trying to get into cancer chemotherapy. We had a relatively extensive library of compounds that we prepared for cancer," he said.

"I sent a few of those off for TB testing, and two of them came back quite promising."

The most effective compound was based on a natural substance found in tropical sea sponges and sea squirts, tiny rock-clinging creatures which start life with animal-like backbones but eventually lose their backbones and evolve into plants.

"We modified the natural properties and changed it in quite a few ways," Dr Copp said.

"We know the compound kills TB that is resistant to all known antibiotics.

"There are particular enzymes or proteins in TB that are specific to TB. If we can find compounds that knock out those targets, then you have a very specific drug."