Page last updated at 18:05 GMT, Wednesday, 10 December 2008

Hopes raised on HIV immune boost

Rhesus monkey
The tests were carried out on samples from rhesus monkeys

Scientists believe successful tests in monkeys could prove a step towards a new type of drug to combat HIV.

The journal Nature reports infected animals survived almost twice as long after a single treatment to raise immune response to the virus.

An independent expert said multiple doses were possible, and might eliminate the virus.

Current antiretroviral drugs must be taken for life, giving HIV the opportunity to build up resistance.

It's possible that multiple doses could eliminate the virus, although the present experiment has not shown that
Professor Thomas Lehner
King's College London

Although millions of people with HIV cannot currently receive them, modern antiretroviral drugs have transformed the life expectancy of people with the infection.

However, scientists are constantly looking for alternative ways to keep the virus in check.

One option is being tested in the US on macaque monkeys infected with "simian immunodeficiency virus" - their equivalent of HIV.

One of the features of HIV is its ability to shut down or impede the body's own methods for clearing viral infections.

In particular, it manages to activate a signalling system in the body's immune cells - which then actually holds back the body's immune response.

The latest treatment works by blocking that signalling system, which has the effect of boosting the function of "killer" immune cells.

The blocking antibody was injected once into nine animals who had developed AIDS after SIV infection, all of whom lived on average almost twice as long as other monkeys who did not receive the treatment.

The treated monkeys had clear signs of more active immune systems and reduction of the amount of virus circulating in their blood, both signs that they were tackling the disease more efficiently.

While the virus was not fully controlled in any of the monkeys, the scientists said that more than one dose was possible, and that it could be used in combination with antiretroviral drugs.

Long wait

Dr Rama Amara, who led the research, said: "It is important to note that this therapy was effective without antiretroviral drugs and in monkeys with severe AIDS.

"It is critical to induce protective immune responses targeting the mutated virus for developing a successful immune therapy to control HIV infection."

Another of the researchers said that the treatment also offered potential against other chronic infectious diseases such as hepatitis C and TB.

Professor Thomas Lehner, an immunologist from King's College London, said that the findings were "very interesting", and that the drug showed potential for human treatment.

He said: "It's possible that multiple doses could eliminate the virus, although the present experiment has not shown that.

"It's my understanding that some groups are already working to test this in humans, and although the safety of the drug is a concern, I see no reason why that should be a problem.

"It's most likely that we will see it used alongside antiretroviral therapy."

Dr Ade Fakoya, from the International HIV/AIDS Alliance, said that the research was "an important avenue" to pursue, particularly as it had managed to extend the lifespan of the monkeys.

However, he said: "There's a long process of many years before this basic research is translated into actual research with the HIV virus in humans and then identifying a way to be able to actively block this on a large enough scale for it to be another useful tool in HIV treatments."

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