HIV vaccine hopes raised by new method for blocking virus

Scientists in the United States are working on a method to block the HIV virus from infecting cells and causing AIDS -- a new approach that could one day lead to a human vaccine.

The new method stimulates muscle cells to produce proteins that act like a gum that binds up the virus’s surface and prevent it from latching onto and infecting healthy cells.

Without host cells to attach to, the virus eventually disintegrates in the body and gets flushed out.

The research was led by scientists at the Scripps Research Institute, who worked in collaboration with teams from several other universities. They recently published their findings in the journal, Nature.

Michael Farzan, an infectious disease specialist at the Scripps Research Institute in Florida and lead author of the paper, says this is a new approach to fighting HIV that doesn't rely on the immune system to produce antibodies against the virus, which is how other vaccines work.

"What we do instead is rely on an inhibitor we developed that has special properties our immune system cannot develop," he told CTV's Canada AM from Jupiter, Fla.

The technique has been tested on four rhesus macaques so far, and it's protected the monkeys for nearly a year against multiple attempts to infect them with several HIV strains.

Farzan says that in their experiments, they used a viral vector to inject a single gene into muscle cells. The muscle cells are then stimulated to become "factories" to make the glue-like protein. This protein, called eCD4-IG, targets two key receptors that the HIV virus uses to get into cells and binds them up.

He says all HIV strains -- no matter how virulent -- have these receptors, which is why the protein is so effective.

"All viruses need to use their receptors, so they're vulnerable to this particular inhibitor," Farzan said.

The research team's approach was actually inspired by the tiny percentage of people who have a rare genetic mutation that makes them resistant to HIV.

Research is continuing on the monkeys, but Farzan says the hope is to one day develop a human vaccine and then run clinical trials to test its safety and effectiveness.

But he notes there have been other research teams that have tried to approach the virus in a similar way, and none of those approaches led to an effective vaccine.

"It is going to be tested on humans, but it is very early days to anticipate those results," Farzan said.

"We've only shown protection in four animals. So what happens in four animals could be very different from what happens in 1,000 humans."