text: A new HIV treatment pioneered using an antibody to attack the virus could lead to a new vaccine to prevent the infection. The first results to emerge from patient trials reveal the experimental therapy can dramatically reduce the level of virus in a patient's blood - their viral load. The scientists behind the discovery believe their findings offer new strategies for fighting or even preventing HIV infection. The antibody was designed by researchers to block the key viral protein receptor that is needed to infect human blood cells. As a result patients injected with the neutralising antibody during the trials saw a 300-fold reduction in their viral load. Scientists at the Rockefeller University in New York believe a new antibody therapy could pave the way for an HIV vaccine after clinical trials revealed the treatment resulted in a 300-fold decrease in the amount of HIV, pictured, in sufferers' blood . In a person infected with HIV, there is an ongoing battle between the virus and the body's immune system. As the body produces new antibodies that target the virus, the infection mutates to escape, managing to stay a few steps ahead. The team of scientists at Rockefeller University in New York now believe that using synthetic antibodies that attached to the surface of proteins on the outer membrane of the HIV virus, could offer an alternative treatment to the anti-retroviral drugs currently used. They hope the breakthrough will result in new therapeutic vaccines. HIV antibodies previously tested in humans had shown disappointing results, but the antibody tested at Rockefeller University belongs to a new generation of broadly neutralising antibodies that potently fight a wide range of HIV strains. Healthy gay men should be given anti-retroviral drugs to 'slash the number of cases of HIV', a groundbreaking study published earlier this year suggested. The Proud study, conducted in England, provides the first evidence that preventative HIV treatment is highly effective in a real-world setting. It showed that pre-exposure to the HIV drug Truvada can reduce the risk of infection in men-who-have-sex-with-men  by as much as 86 per cent. Previous research had suggested that preventive treatment might cut HIV infection rates but it was unclear whether such an approach would work in practice. 'One antibody alone, like one drug alone, will not be sufficient to suppress viral load for a long time because resistance will arise,' said Dr Marina Caskey, co-first author of the study. 'What's special about these antibodies is that they have activity against over 80 per cent of HIV strains and they are extremely potent.' The research showed the new antibody therapy was effective against 195 of 237 HIV strains. The immune systems of people infected with HIV naturally produce broadly neutralising antibodies in 10 to 30 per cent of sufferers, but only after several years of infection. By that time, the virus has typically evolved and mutated to a point rendering the powerful antibodies ineffective. However, by isolating and cloning these antibodies, researchers are able to harness them as therapeutic agents to use against HIV infections that have had less time to evolve. As part of the new study, uninfected and HIV-infected people were given a single dose of the antibody intravenously, and monitored for 56 days. At the highest dose level - 30mg per kilo of weight - all eight infected people treated showed up to a 300-fold decrease in the amount of HIV virus measured in their blood. Most of those participants reached their lowest viral load just one week after treatment. The study marks the first time the new generation of HIV antibodies has been tested in humans. Dr Marina Caskey, co-first author of the study, said: 'What's special about these antibodies is that they have activity against over 80 per cent of HIV strains and they are extremely potent.' (File picture) Dr Caskey said further trials could result in the antibodies being used in conjunction with existing anti-retroviral drugs to maintain better control over the infection to prevent the onset of Aids. She said antibody therapy might require treatment once every few months, compared with daily doses of antiretroviral drugs, currently the front line treatment for the virus. Besides the possibility of treatment, the study also raises hopes for an HIV vaccine. Dr Caskey said that if researchers can induce an uninfected person's immune system to generate potent antibodies such as that tested, it might be enough to block the HIV infection before it can be established. The study was published in the journal Nature.
target: New antibody blocks protein receptor needed to infect human cells .
  Patients injected saw 300-fold reduction in amount of HIV in their blood .
  Scientists believe breakthrough could result in new vaccines against virus .