Souped-up immune cells catch even disguised HIV

By Maggie Fox, Health and Science Editor

WASHINGTON (Reuters) - Genetically engineered immune cells can spot the AIDS virus even when it tries to disguise itself, offering a potential new way to treat the incurable infection, researchers reported on Sunday.

The killer T-cells, dubbed "assassin" cells, were able to recognize other cells infected by HIV and slow the spread of the virus in lab dishes.

If the approach works in people, it might provide a new route of treating infection with the deadly human immunodeficiency virus, the researchers in the United States and Britain said.

"Billions of these anti-HIV warriors can be generated in two weeks," said Angel Varela-Rohena of the University of Pennsylvania, who helped lead the study.

In a second, unrelated report, researchers testing Dutch biotechnology firm Crucell NV's experimental AIDS vaccine said it prevented infection in six monkeys.

The animals were infected with a monkey version of HIV called SIV, and the vaccine used a virus that is dangerous to use in humans, so it is not ready for human tests.

But, writing in the journal Nature, Dr. Dan Barouch of Beth Israel Deaconess Medical Center and Harvard Medical School in Boston and colleagues said it shows there is still hope for developing a vaccine against AIDS.

The AIDS virus, which infects 33 million people globally, is especially hard to fight. Like all viruses, it hijacks cells in its victims, forcing them to become little viral factories and make more virus.

ESCAPE AND EVADE

HIV is even more insidious, attacking immune system cells called CD4 T cells, which help mount a defense. It can also disguise itself to escape CD8 killer cells, also known as cytotoxic T lymphocytes or CTLs.

"CTLs are crucial for the control of HIV infection. Unfortunately, HIV has an arsenal of mutational and nonmutational strategies that aid it in escaping from the CTL response mounted against it by its host," the researchers wrote in their report, published in the journal Nature Medicine.

One good defense allows HIV to hide a protein called HLA-I-associated antigen.

Varela-Rohena and colleagues took T-cells from an HIV patient and created a genetically engineered version that recognizes this deception.

"It is possible to improve on nature when it comes to preventing HIV CTL escape," they wrote.

Not only could the engineered T-cells see HIV strains that had escaped detection by natural T-cells, "but the engineered T cells responded in a much more vigorous fashion so that far fewer T-cells were required to control infection," Penn's James Riley, who also worked on the study, said in a statement.