February 19, 2015
Protein inactivates virtually all strains of HIV
An effective vaccine against HIV has eluded scientists for decades, but new research published Wednesday in the journal Nature may provide the next best thing: a technique which inactivates virtually all strains of the virus using a genetically engineered protein.According to U-T San Diego, scientists from the Scripps Research Institute in Florida and a team of colleagues from throughout the US and France have developed a protein that mimics a pair of receptors on the surface of the immune cells that are infected by the AIDS-causing virus.
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When HIV encounters this protein, it starts behaving like it does when it is infecting a cell. This process causes changes in the virus that prevents it from any future attempts at infection, and the protein was 100 percent successful against neutralization-resistant strains of HIV-1, HIV-2 and SHIV-AD8 (an artificially-made blend of HIV and a similar disease that affects monkeys).
Could be a few years, though
While the study authors said that it will still be several years before their technique can be tested in humans, the newspaper reports that it has promise as a new way to protect people against HIV infection. It was tested in cell cultures, and it reportedly offered a level of protection far better than even the most powerful anti-HIV antibodies found naturally in the body’s immune system.
Scripps Research scientist Michael Farzan, who led the study, said that the method could one day offer long-testing protection against HIV infection through gene therapy. An innocuous virus would carry a designated gene (eCD4-Ig) into a person’s muscle cells, where it would release the protein into the blood stream. Any HIV it encountered would bind to it, becoming harmless in the process, causing the approach to be just as effective as a vaccine against the virus.
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“If we injected in a high risk individual who is not HIV positive, theyll be protected,” he explained. “We did this very stringent HIV challenge (in animals) and we kept doubling the doses. In this paper we only went four times but now we've given 16 times the dose to infect our control animals. And these animals were completely uninfected – zero virus. So this is better than anyone has ever shown in an animal for protection.”
Once they proved that HIV would latch onto eCD4-Ig, they had to make sure the protein could be produced naturally by test animals, according to the Los Angeles Times. In order to do so, they used an adeno-associated virus (AAV), which infects humans and other primates but does not cause illness, and altered its genome so that it would produce the enhanced protein.
They then infected four macaques with the altered virus, and found that it integrated with the genome of host cells, which made it possible for them to produce the protein. The monkeys were then repeatedly injected with SHIV, and 34 weeks later, none of them had become infected with the virus. The findings indicate that AAV-expressed eCD4-Ig could be effective against HIV.
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“The science is very good. It's quite impressive that they managed to combine the CD4 binding site and the CCR5 to really block HIV so efficiently,” Shane Crotty, a vaccine expert at the La Jolla Institute for Allergy and Immunology who was not involved in the research, told U-T San Diego. “It's a really nice first experiment.”