BARCELONA, July 8: The world’s biggest trial of a vaccine aimed at preventing HIV infection was announced here on Monday, but AIDS campaigners remained in the dark about the outcome of another desperately-awaited vaccine in the test pipe.

The five-year trial will start in Thailand later this year, enrolling 16,000 volunteers, with the aim of priming the two arms of the immune system — antibodies and cells — to the human immunodeficiency virus (HIV).

The green light depends on final approval by the US and Thai authorities, which have military and civilian health institutes in the project, the organisers said on the sidelines of the 14th International AIDS Conference here.

Even though HIV was identified more than 20 years ago, there still is no vaccine or cure for it, although there is now a widening group of treatments to dampen virus levels in the body.

The Thai test will be the first mass assessment of a novel combination approach, but some scientists say trials on smaller groups of volunteers raise doubts about whether it will work.

The idea is to “prime” the body with one vaccine — ALVAC-HIV, made by Aventis Pasteur of France — and then provide a boost with another, AIDSVAX B/E, made by the US firm VaxGen, a unit of the biotech giant Genentech.

The trial will unfold among volunteers in Chon Buri and Rayong provinces in eastern Thailand.

Half of the participants will receive the two vaccines, injected at four occasions over the first six months, while the others will receive injections of a placebo, a dummy substance.

New drug: A revolutionary AIDS drug that stops the HIV virus from entering cells may offer new hope to thousands of patients resistant to current therapies.

Data released on Monday by drug makers Roche Holding AG of Switzerland and US biotech firm Trimeris showed T-20 slashed the amount of virus in the blood of many patients running out of treatment options.

The injectable drug, which could reach the market in the first quarter of next year, is the first in a novel class of medicines known as “fusion inhibitors” that work in a completely new way to outwit HIV, the virus that causes AIDS.—AFP/Reuters