NEW YORK, Jan 29: Monkeys got unusually mild infections from a cousin of the AIDS virus after scientists gave some of their blood cells a gene to interfere with the virus' reproduction. The findings lend support to the idea of treating HIV-infected people with such gene therapy.The monkeys studied were infected with the Simian Immunodeficiency Virus, or SIV. Those treated with the gene therapy showed much less virus in their bodies and far less damage to their lymph nodes. They also showed no drop in their blood counts of disease-fighting Cd4 cells, while untreated animals showed a steep decline. ``The inserted gene blocked chemical orders'' issued by two SIV genes to infected cells. With those orders stymied, the virus couldn't reproduce.
``So the treated cells became a dead end for that virus,'' said Richard Morgan, an author of the study in the February issue of the journal Nature Medicine. He is a researcher at the National Human Genome Research Institute, part of the National Institutes of Health inBethesda, Maryland.
Researchers treated three rhesus macaques. They drew blood from the animals, inserted the gene into Cd4 cells, and returned them. A week later, the animals were deliberately infected with SIV. At that time, only about two to ten per cent of Cd4 cells in the treated animals' blood carried the therapeutic gene. But that was enough to dampen the infection.
Morgan speculated that those relatively few cells may have proved especially attractive to SIV because they had been ``activated'' or turned on to fight germs, during the treatment.
SIV prefers to infect activated cells. The treated cells may have acted like sponges, taking in virus but not allowing it to make any progeny to get back out again, Morgan suggested.
Gary Nabel of the University of Michigan Medical Center in Ann Arbor, Michigan, who is also studying gene therapy for HIV infection, called the monkey work encouraging. But he cautioned that the implication for human therapy isn't clear.
Copyright © 1998 Indian Express Newspapers (Bombay) Ltd.
