A new study has shown that a single injection of antibodies that target HIV can protect monkeys from contracting the virus for nearly six months.
The study, published yesterday in Nature, is an important step in the development of a new treatment that could prevent HIV infections in people, with potentially far more effectiveness than any other contemporary method.
In the study, US and German researchers used four powerful antibodies, produced by some HIV+ people, known to neutralise several strains of HIV. In the study macaques were injected with a different antibodies, and were then exposed to the HIV virus.
The research found that the antibodies protected the macaques from becoming infected for 12 to 14 weeks on average. Some animals were even protected for as long as 23 weeks. For monkeys without the antibody, it took an average of three weeks to become infected with HIV.
“The result is surprising,” told Ruth Ruprecht, to The Verge, who directs the AIDS Research Program at Texas Biomedical Research Institute and did not take part in the study. “I am astonished by how long protection lasted.”
Preventive HIV medications already exist, PrEP, for example, reduces the risk of infection by well over 90 percent. The main problem of PrEP is treatment routine disruption, the pill needs to be taken daily if it is to be effective.
A vaccine has so far been elusive, but protection for nearly six months with a single injection of antibodies, may be the next best thing. “What the data in this study is suggesting is that six months [of protection] may be achievable and with improved technologies we might even do better than that,” said David Montefiori, the director of the Laboratory for AIDS Vaccine Research and Development at Duke University.
Ruprecht pointed out that the researchers could have achieved better results by using a cocktail of antibodies in the monkeys, instead of injecting each group of macaques with a single antibody: “When you combine antibodies that have different specificities, you decrease the chance of creating immunization-resistant viruses,” she said. When mixed together, the antibodies “reinforce each other, synergize, and what that will mean is that the protection will be much more potent.”
Malcolm Martin, the director of the Viral Pathogenesis and Vaccine Section at the National Institute of Allergy and Infectious Diseases, who co-authored the study, said that the next step is to begin testing on humans, and he is optimistic about the preventative potential: “With the extraordinary progress that’s been made just in the past six years, I’m more optimistic than ever that the field will eventually succeed in having an effective prevention measure,” he said, whether it’s the antibodies or an actual vaccine. “Hopefully, we’ll see the light at the end of the tunnel within the next 10 years.”