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Thursday, 17 January, 2002, 10:28 GMT
Development in Aids vaccine hunt
HIV cells
Aids is notoriously difficult to target with vaccines
Scientists have reported progress in the quest for an HIV vaccine by managing to control the infection in monkeys.

However, their optimism is countered by a discovery that the virus can possibly mutate and side-step the treatment.

They found monkeys injected with an experimental vaccine can suppress the Aids virus in their bodies to remarkably low levels.

While this research looks encouraging we know there's a long way to go before a cure is found

Terrence Higgins Trust spokeswoman
Seven of the eight monkeys injected with the vaccine fought the HIV infection.

Aids is notoriously difficult to target with vaccines, which cannot produce antibodies against a broad range of HIV strains.

The US team carrying out the research used a different gene-based vaccine designed to make the macaque monkeys produce immune system T-cells which attack and destroy virus-infected cells.

Virus control

The strategy was tested on animals exposed to a powerful hybrid of human and monkey versions of the Aids virus, known as SHIV.

Vaccination did not prevent infection, but helped to bring it under control and slow its progression, it was revealed in an article in Nature, the British science journal.

After 70 days, infected animals showed markedly lower levels of the virus, while the number of T-cells remained high.

Emilio Emini, who led one research team in Pennsylvania, said they were convinced Ad5 vaccine was a "promising vaccine vector" for combating HIV-1, the most widespread form of the virus.

Virus mutation

A pessimistic note was sounded by another team in Boston, led by Dan Barouch of Harvard Medical School, who found one of the eight vaccinated rhesus monkeys had failed to fight SHIV.

Examination of the virus in this animal suggested the strain had mutated, enabling it to evade the vaccine.

The UK-based HIV and Aids charity the Terrence Higgins Trust is pleased with the findings.

Macaque monkeys
Most monkeys fought HIV infection
A spokeswoman said: "This research shows just how difficult it is to develop effective vaccines against this pernicious virus.

"There are many different strains of HIV, each able to mutate to survive.

"So while this research looks encouraging, we know there's a long way to go before a cure is found."

Since it was first identified 20 years ago, Aids has killed more than 20 million people and another 40 million are currently infected with HIV.

See also:

03 Apr 01 | Health
Polio eradication draws closer
11 Apr 01 | Health
Threat from drug-resistant HIV
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