In a world where you can catch a cold in Bombay and your first sneeze is in Brisbane, the outbreak of infectious diseases across national borders is an everpresent threat. Monash micro- biologists are helping to crack the DNA codes of the bad bugs to find out what makes them behave the way they do. David Bruce reports.

"The single biggest threat to man’s continued presence on the planet is the virus", said Nobel laureate Joshua Lederberg in 1958.

In a world recovering from the devastation of a world war and becoming preoccupied with the awesome power of an atomic bomb, Lederberg’s claim may have seemed overstated. But at the end of the 20th century, most microbiologists think Lederberg got it right on the nail.

Infectious diseases are among the greatest causes of human suffering and death next to war and famine - and the latter two rarely occur in absence of the first. The modern epidemics of HIV and hepatitis and the increase in tuberculosis have been joined by new viruses leaping across continents and crossing from other species to humans. In many diseases, the antibiotics pioneered throughout this century are now confronting resistance in their previously unhindered work inside the human body.

The bugs are fighting back, and a new offensive is being fought by research institutions the world over, including at Monash University’s Department of Microbiology.

In a world so much smaller because of modern travel and transportation, only a few hours are needed to spread a disease across the global village.

"We have basically been playing catch-up since the 1940s," explains the head of the department Professor Ben Adler. "Whenever an antibiotic is discovered, resistant bacteria have appeared soon after. It only took four years from the time penicillin was discovered for resistant bacteria to emerge.

"Bacteria have incredibly short generation times. A cell can divide into two in about 20 minutes - that is one generation. Because they replicate so quickly they also evolve and adapt to new environments quickly. To get through hundreds of human generations takes centuries - for bacteria it takes only days."

Over the past century, science has made great advances in the elimination of such killers as smallpox and polio and most recently the Hib bacterium. In others, such as some forms of hepatitus, malaria, tuberculosis and HIV, there are still no effective vaccines, and treatments need to be continually developed.

"We have to take infectious disease resurgence extremely seriously to stay ahead. Some of the battles we appear to have won, but others we are quite clearly losing," said Professor Adler. At Monash, microbiologists are working on several research projects including those with malaria, tuberculosis, dengue fever, dysentery, Ross River fever, and several infectious diseases that occur in agricultural industries.

The biggest weapon in the armory of microbiologists is genetic engineering, introduced over the last two decades and now leading to significant advances in the development of treatments and vaccines.

"We have now entered a new era in our understanding of viruses and infectious diseases, having moved from the discovery of these bugs to understanding why they behave the way they do," Professor Adler said.

Monash researchers Professor Ben Adler and Ms Kylie Farrow.

Kylie Farrow, a postgraduate student in the department, has used genetic manipulation and gene sequencing to determine a vital DNA sequence within a human intestinal pathogen called Clostridium difficle. The bacterium causes severe and bloody diarrhoea and intestinal haemorraging and is most commonly acquired after a patient receives antibiotic treatment in hospital. This bug carries a gene which confers resistance to antibiotics that are commonly used for the treatment of infectious diseases.

"Because of its mobile nature, it is able to transfer to other species of bacteria which then become resistant to these antibiotics," explained Ms Farrow. "Understanding the DNA sequence of the antibiotic resistant gene will hopefully lead to an understanding of how it spreads between bacteria. And this may help doctors prescribe better antibiotic therapies with fewer side-effects for hospital patients."

TOP