Tests of `superior' Aids vaccine open

American researchers said yesterday they were starting tests of a new vaccine against the Aids virus in people and said this one was far superior to earlier failed efforts.

Julia Hurwitz and Karen Slobod of St. Jude Children's Research Hospital in Memphis, Tennessee, said the US Food and Drug Administration (FDA) had given them the go-ahead to start safety trials in human volunteers. They said their vaccine, which uses part of the protein coating of the human immunodeficiency virus (HIV), was meant to protect healthy people against infection and not to help those already infected.

"The whole point of the vaccine is to alert the immune system against a pathogen that may appear in the future," Hurwitz said. "If we can wake them up by showing them the shape of a foreign agent before it comes along, then they can block that agent."

They said they would be recruiting between nine and 18 healthy volunteers for the Phase I clinical trial, which focuses on safety alone and not on whether the vaccine works.

The St Jude vaccine uses outer protein layers known as envelopes from 23 different mutations of HIV, each contained in a smallpox vaccine.

"Our concern is that HIV is a master of disguises. One HIV may have an envelope that looks like a circle. Another may have one that looks like a square, another like a triangle and so on," Ms Hurwitz said.