- 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.
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- "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.
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- 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.
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- 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.
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- 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.
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- 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.
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-
- 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.
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- 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.
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- 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.
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- "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."
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- 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."
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