New AIDS Vaccine Success
In Monkeys - Human Verdict
In '3-5 Years'
SYDNEY (Reuters) - Australian scientists said on Wednesday they had created a breakthrough vaccine which enables monkeys to fight off the HIV virus, and plan to start testing it in humans next year.
"It looks good so far. We just hope that it holds up when we get a chance to test it (in humans)," Dr Alistair Ramsay, an immunologist at Australian National University, told Reuters.
Researchers in Canberra and Melbourne separately administered two vaccines, one to prime the immune system and another to boost it into action, before infecting four monkeys with the HIV virus.
The monkeys were initially infected but produced large numbers of "killer T cells" to clear the virus from their system within weeks. Four unvaccinated monkeys contracted the virus, which causes AIDS in humans but not in monkeys.
The body's T cells are its first line of defence against infection, targeting and destroying foreign invaders. The researchers described their work in a scientific paper published in the U.S.-based Journal of Virology on Wednesday.
The researchers from the ANU, the Australian government's Commonwealth Scientific and Industrial Research Organisation (CSIRO) and Macfarlane Burnett Centre, combined two immunisation methods, neither of which is effective on its own.
First, "DNA immunisation" introduced a modified HIV gene into the monkeys' skin cells and stimulated their immune systems. Then, a few weeks later, "viral immunisation" introduced the same HIV "gag" gene in a harmless fowl-pox vector vaccine, producing a sharp surge in the number of T cells. When the macaque monkeys were then infected with HIV the T cells multiplied even further and began to attack cells infected by the virus.
The World Health Organisation says up to 40 million people around the world are living with the AIDS virus, with Africa the worst-affected continent but Asia also facing a pandemic. The disease killed an estimated 2.3 million people last year.
Ramsay said AIDS vaccine teams around the world were focusing on the "CD8 T cells"-- but the Australian effort was the first to use the dual vaccine procedure to boost them.
The Australian team plans to use the fowl-pox vaccine in a therapeutic trial on HIV carriers in Sydney and Melbourne next year to see if the vaccine could help ward off AIDS, he said.
Then it hopes to start overseas trials on non-infected humans, probably in Southeast Asia.
The team hopes to win U.S. funding, probably from the U.S.-based International AIDS Initiative, which helps speed the development of candidate vaccines, Ramsay said. "We would hope to be in clinical trials within two years-- and we'd know within three to five years if it worked," he said.
Another ANU scientist, Professor Ian Ramshaw, said current weapons against AIDS-- condoms to avoid infection or a cocktail of drugs to fight it-- were either too expensive or for various reasons too hard to distribute in the Third World.
"A vaccine is the only answer," Ramshaw said. "The advantage of our system is it is very cheap and does not require refrigeration which can be a major difficulty in tropical countries. The vaccine will cost only a few cents per shot and can be administered without expensive equipment or training."
Another researcher involved in the potential vaccine, CSIRO animal health specialist David Boyle, was more guarded. "I'm quite cautious about HIV vaccines because there've been a lot of efforts so far and none has been successful," Boyle told Reuters. "Until you test it there's been no proof of the pudding."