INFECTIONS
April 17, 2015

Antibody with Super Powers to Fight HIV

The broadly neutralizing antibody 3BNC117 is active against over 80% of HIV strains and is well-tolerated.

Human Immunodeficiency Virus (HIV), the virus that causes AIDS, is very resourceful: it is constantly changing, or mutating. These frequent mutations make it difficult for the immune system to marshal effective antibodies against the virus.

Luckily, technology is also resourceful. New methods of cloning — exactly copying — antibodies have led to the discovery of what is known as broadly neutralizing antibodies. These next generation molecules can potentially target many different HIV strains.

The eight HIV-infected people who were given the 30 mg/kg dose showed up to a 300-fold decrease in viral load.

“What's special about these antibodies is that they have activity against over 80 percent of HIV strains, and they are extremely potent,” Marina Caskey, one of the lead researchers on a new study looking at the safety and tolerability of a particular broadly neutralizing antibody, said in a statement.

Caskey and her colleagues at Rockefeller University tested the antibody, known as 3BNC117, for the first time in humans. It had previously proven effective at reducing the amount of HIV virus detectable in the blood, known as the viral load, in mice and non-human primates.

“We had very promising results [in earlier studies]…But when you go to humans, it's always different,” Florian Klein, the other first author on the study, told TheDoctor.

Happily, 3BNC117 not only reduced viral load, but was also well tolerated by participants in the current study.

Twelve uninfected volunteers and 17 HIV-infected volunteers who were not receiving antiretroviral treatment were given a single intravenous 1, 3, 10 , or 30 mg/kg dose of 3BNC117. During the eight-week follow-up period, 3BNC117 was found to be safe and well tolerated in both groups of study participants, and with no serious adverse events reported.

In four of the eight individuals receiving the highest dose, viral load remained below pre-infusion levels during the follow-up period.

This was really a proof of concept study to show that antibodies can work in HIV-infected individuals and they can suppress viral load, said Klein. Researchers will continue to look at how this broadly neutralizing antibody might be combined with current HIV treatment regimens. We may be able to improve treatment and make anti-HIV therapy even better, Klein added, because this antibody is effective for a much longer time period than currently available HIV drugs.

“We suspect that a single antibody, even if you give it multiple times, cannot do the entire job, because at some point HIV will become resistant,” said Klein, who along with Caskey works in the laboratory of Michel Nussenzweig at Rockefeller University.

The researchers hope to eventually understand how the antibody fights HIV so that they might be able to modify the process and make the antibody even more effective.

The current study was published recently in Nature.

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