A new batch of drugs that slow the progress of HIV in patients and genetically modified cells that prevent further infections are about to become available or trialed, doctors told the world's largest AIDS conference.

"It's an extremely exciting time in terms of drug development. We have better drugs in existing classes, as well as whole new classes of drugs," said Professor David Cooper, co-chairman of the 2007 IAS conference in Sydney.

"Patients and their clinicians now have a much wider choice of drug combinations than ever before," said Cooper, director of Australia's National Centre in HIV Epidemiology and Clinical Research at the University of New South Wales.

But the biggest breakthrough for the world's poorest nations, which will not initially be able to afford these new drugs and which carry the heaviest AIDS burden, lies in a procedure dating back to at least 2,300 B.C. in Egypt - circumcision.

Millions of new HIV infections could be avoided if more men were circumcised, IAS conference was also told.

African studies have shown that male circumcision can reduce HIV transmission from women to men by about 60 percent, said Professor Robert Bailey at the School of Public Health at the University of Illinois at Chicago.

Universal circumcision could avert two million new infections and 300,000 deaths in sub-Saharan Africa over 10 years, he said.

"If we had a vaccine that was 60 percent protective we would be very happy and rolling it out as fast as possible," Bailey told the IAS conference in Sydney.

"But no one stands to profit from male circumcision - no one but the 4,000 in Africa who will be infected tomorrow."

The idea of using circumcision as a weapon against AIDS emerged after studies in Uganda, Kenya, Malawi, Zambia and the United States found the potential to significantly reduce infections, said Bailey, adding the World Health Organisation has now endorsed circumcision as a disease prevention method.

"The challenge ahead for us is how to roll out circumcision safely ... and to persuade leaders in countries that it is going to help their populations," Bailey told a news conference.

New drugs

New drugs and improved second-generation drugs will not only be more effective in fighting HIV, the IAS conference was told, but could offer treatment to patients whose disease had become immune to earlier drugs.

Recent research has shown that new classes of anti-retroviral drugs, which include various inhibitors, provide superior benefit to patients with highly resistant HIV, said Joseph Eron, professor of medicine at the University of North Carolina.

"I think that while it will take some time, some of these new agents will also be very useful in the developing world were we are seeing the emergence of resistant virus," said Eron in detailing the new drugs.

At the cutting edge of the AIDS battle is genetic engineering, with human trials about to start on genetically modifying a HIV patient's blood stem cells and T cells and reintroducing them into the body to better fight the disease.

"This is a permanent modification of the cells. As long as the cells persist in the patient they will be resistant to further infection," said Professor John Rossi, head of biological sciences at the U.S. Beckman Research Institute.

"We realise that this is not a treatment that will be applied universally," said Rossi, adding the treatment should allow patients to reduce drug dosage.

Rossi and Eron called on drug companies to make new drugs available to the world's poorer nations.

Medecins Sans Frontieres (MSF) told the IAS conference said that while there had been dramatic price reductions in some HIV drugs, the newer, less toxic drugs recommended by the WHO had become more expensive. An MSF report said some new drugs had risen in price by nearly 500 percent from $99 to up to $487.

The United Nations says close to 40 million people are infected with HIV and that treatment had dramatically expanded from 240,000 people in 2001 to 1.3 million by 2005.