Students at an event organised by an AIDS control society in Hyderabad

New Delhi, June 30: Researchers have engineered the surface of white blood cells to make them resistant to the human immunodeficiency virus (HIV), kindling hopes of a new and long-lasting treatment for HIV.

In studies on mice and human blood cells, a 23-member research team in the US has created HIV-resistant white blood cells and shown that these transformed cells can protect mice from infection with the virus.

Using custom-made molecular scissors, researchers altered a gene in CD4 T cells — HIV’s target cells — to create a set of modified T cells that do not allow the virus to enter them. The results have bolstered hopes for a therapy in which doctors would extract T cells from HIV infected people, alter them, and re-inject them back into the body where they would multiply without allowing HIV to enter and proliferate.

The experiments on mice suggest that such altered cells provide “robust and stable” protection against HIV, the researchers have said in a report to appear in the journal Nature Biotechnology .

“It is a very promising technology,” said Elena Perez, a paediatric immunologist and team member at the Children’s Hospital of Philadelphia. Not only are the modified T cells protected from HIV, they also give rise to daughter cells resistant to HIV.

“We’re modifying a population of CD4 T cells and re-infusing them. So, hopefully, there’ll be a protected population of cells that will multiply and boost the immune function of patients,” Perez told The Telegraph.

The laboratory results have prompted scientists to initiate work on human clinical trials. The first such trial, primarily aimed at evaluating safety of the technique in humans, is being planned for the end of 2008 or early 2009.

The technique involves tweaking a molecule called CCR5 found on the surface of T cells that HIV uses as a gateway to slip into the cells. Scientists have known that a specific mutation in the CCR5 gene prevents HIV infection. A small proportion of people who carry this CCR5 mutation are naturally immune to HIV — despite exposure to the virus, they remain uninfected.

Perez and her colleagues used custom-designed enzymes called zinc finger nucleases as molecular scissors to snip off segments of the CCR5 gene inside the T cell to mimic the mutation and turn the cells resistant to HIV.