JUNE marks 30 years since the first report of AIDS – a syndrome that has killed an estimated 25 million people worldwide. Yet this year’s anniversary is somewhat arbitrary: the virus responsible for AIDS has probably been circulating within human populations for 100 years. Why did it take so long to detect it? In June 1981, doctors reported an unusual type of pneumonia in five previously healthy young homosexual men in Los Angeles. Two years later the cause of their immunodeficiency was identified: a retrovirus that targets white blood cells,subsequently named human immunodeficiency virus (HIV). Similarities with the simian immunodeficiency virus (SIV)

A PIONEERING treatment to thwart HIV by genetically altering blood cells so the virus cannot invade them has shown promisein the first nine people to receive it. The treatment involves taking the white blood cells most prone to infection by HIV, called CD4+ cells, from someone with HIV. These are then altered in the lab to sabotage a gene called CCR5, before being returned to the patient. Because CCR5makes the molecular “door-handle” by which HIV enters cells, treated cells become impossible for the virus to infect. “This is the first example of genetic editing to introduce a disease-resistant gene in patients,” says lead investigator Carl June at the

For the first time, an HIV-like infection has been cleared from an animal without the use of antiviral drugs. The infection was eliminated from mice using a human protein that peps up immune cells. Marc Pellegrini from the Walter and Eliza Hall Institute of Medical Research in Melbourne, Australia, and colleagues infected mice with lymphocytic choriomeningitis virus (LCMV), which causes a chronic infection that spreads throughout the body. “The virus overwhelms mice, mimicking the massive viral loads associated with HIV infection in humans,” says Pellegrini. Eight days after infection, some of the mice were injected with human interleukin-7 (IL-7) – a chemical messenger that plays