Washington, Nov 7 (IANS): Scientists have precisely edited human blood forming stem cells and T-cells to create what could prove to be an effective technique for blocking HIV from invading and destroying patients' immune systems.

This new approach to HIV therapy might be ready for human safety trials in less than five years, the researchers said.

They used a relatively new gene-editing technique called CRISPR Cas technology.

The new work is "a tremendous first step in editing out what makes human cells vulnerable to HIV", said David Scadden from Harvard Stem Cell Institute.

"It makes possible the idea that a person's own immune cells can attack HIV without being susceptible to it. That's a powerful concept," Scadden added.

HIV specifically targets T-cells, a principal portion of the blood-based immune system, and enters via a gene receptor called CCR5 that serves as a doorway into the cells.

Once inside the T-cells, HIV replicates and kills off the host cells, leaving patients at the mercy of a variety of opportunistic infections.

Using the CRISPR Cas gene-editing technology, the researchers knocked the CCR5 receptor out of blood stem cells that they showed could give rise to differentiated blood cells that did not have CCR5.

In theory, such gene-edited stem cells could be introduced into HIV patients via bone marrow transplantation.

"We showed that you can knock out CCR5 very efficaciously," lead researcher Chad Cowan, associate professors at Harvard University.

The study appeared in the journal Cell Stem Cell.