A small trial of an experimental antibody “significantly” decreased levels of HIV in humans for nearly a month, according to research published Wednesday in the journal Nature, and researchers say this development could push forward a whole new class of treatment for HIV.

Researchers gave a single intravenous dose of the antibody, 3BNC117, to 29 volunteers, 17 of whom were infected with HIV and 12 who were not. The eight HIV-infected people who received the highest dose cut their viral loads by “up to 300-fold,” researchers said, an effect that lasted 28 days.

Among the patients who received the highest dose, the levels of the virus in their blood was the lowest a week after they received the antibody. But viral loads shot back up toward the end of the eight-week trial in four of those eight patients. That meant that their bodies were developing resistance to the antibody and that it would likely need to be combined with anti-HIV drugs to be effective, the study said.

Still, the researchers said that the early-phase trial proved the antibody was safe for use in humans, whether HIV-infected or not.

“This represents potentially a new class of drugs with activity against HIV,” study co-author Dr. Marina Caskey of New York City's Rockefeller University told AFP. “It is possible that 3BNC117 and antibodies like it will boost the patient’s own immune responses, leading to better control of their infection.”

The antibody was created in a laboratory by cloning what is known as a broadly neutralizing antibody, found in some humans whose immune systems are able to fend off most strains of HIV after they are infected with the virus.

“What’s special about these antibodies is that they have activity against over 80 percent of HIV strains and they are extremely potent,” said Caskey in a press release.

This cloning technique has been used to treat cancer, but it has proved difficult and expensive to use for HIV because the virus constantly mutates in order to evade antibodies. But by isolating and cloning broadly neutralizing antibodies, researchers are hoping to treat HIV before the virus mutates.

Current standard treatment for HIV employs a cocktail of antiretroviral drugs that keeps the virus from replicating, and it has allowed people with HIV to live healthy and long lives. But the drugs can have significant side effects, and they are expensive, often prohibitively so for people without insurance or in developing countries. Also, failure to adhere to a daily regimen can reduce the drugs’ effectiveness.

Antibody treatment, on the other hand, could be administered every few months rather than every day, though that possibility is still years away, the researchers say.

Besides the possibility of HIV treatment, the study raises prospects for a vaccine.

“If researchers can induce an uninfected person’s immune system to generate potent antibodies such as 3BNC117, it might be enough to block the HIV infection before it can be established,” said a press release from Rockefeller University.

With wire services