A new protein aimed at preventing HIV infection in humans has proven itself in initial lab tests. The protein is a mash-up of two previously existing proteins that occur naturally in humans.

While existing HIV therapies target the virus after it has started to make itself a part of its host’s cells, the new protein acts on the virus at a much earlier stage, rendering the virus ineffective before it can do any harm.

“It’s a new approach,” says Martha Neagu, the lead author of the paper announcing the findings, “and it’s a very effective approach.”

The idea to create this protein came from a previous study of South American owl monkeys, in which a similar compound protein was identified as the mechanism behind the monkey’s immunity to HIV. Human cells don’t produce this compound protein, but they do produce its two constituents.

“This is a modular protein, and we have the tools in our human gene arsenal to make an equivalent,” said Neagu. She and her team at Columbia University constructed their own version of the monkey’s HIV inhibitor by splicing together the genetic codes of the components that are already found in humans, creating eleven potential blueprints for the compound protein.

This hybrid code was then inserted into the genetic sequences of human white blood cell lines, and the resultant cells were tested for immunity against HIV. Of the eleven new proteins produced, three were found to be very effective in restricting HIV-1 activity, forming cytoplasmic bodies that disabled the virus within minutes of its entering the cell.

The results of these tests, discussed in the October edition of the Journal of Clinical Investigation, suggest that the new protein is much more potent than other known HIV-1 inhibitors, including even the owl monkey protein that it was modeled after. The protein, known as hT5Cyp, proved nearly ten times more effective in blocking HIV-1 infection compared to the protein responsible for HIV inhibition in old world rhesus monkeys.

And it is much more versatile than these other known inhibitors. The new protein was able to effectively block several “wild type” strains of the HIV-1 virus that have appeared over the past few decades and that have proven more difficult to inhibit.

Any direct tests of the effectiveness of the protein in humans are a long way off, but Neagu, together with a team of Swiss researchers, came up with a rough approximation.

They used seven of the Swiss team’s mice, which have been genetically modified to have immune systems more comparable to that of humans, and transferred hT5Cyp-producing white blood cells into three of the mice while inserting an ineffective variant of the new protein as a placebo into the other four.

Twenty-five days after infecting the mice with HIV-1, the researchers saw that the mean amount of HIV-1 present in the three mice equipped with effective hT5Cyp was only thirty percent of that seen in the remaining four. The virus could still infect normal white blood cells, but the new cells armed with the protein were healthy and fending off the virus.

Though years of additional tests and hurdles necessarily remain, the group is optimistic about the promises the protein holds in enabling an effective means of HIV-1 treatment through gene therapy.

Much of the protein’s effectiveness comes from the way it operates. It binds quickly with the outer shell of the HIV-1, disabling it before it can interact with the host cell’s genome.

As HIV replicates through reverse transcription, an uploading of its own genetic code into that of its host cell, it can’t replicate when it is blocked by the virus. This helps to prevent the virus from adapting to the treatment.

Throughout the study, the researchers were unable to find a strain of HIV-1 that could work around the new protein, though they specifically set up a few trials with the goal of creating one.

But even Neagu is cautious about these results. “This is always to be taken with a grain of salt,” she says, “nature can always outwit us.”