New HIV vaccine trial starts in Sydney

A large clinical trial has begun enrolling volunteers in Sydney to test a novel HIV vaccine that could potentially prevent infection or delay the course of HIV progression in people exposed to HIV, the human immunodeficiency virus that causes AIDS.

UNSW’s National Centre in HIV Epidemiology and Clinical Research (NCHECR), through St Vincent’s Hospital, will conduct the international vaccine trial. Sponsorship for the trial is provided by Merck Sharp & Dohme (Australia), whose parent company has developed the vaccine being tested in the trial.The trial is being run among HIV-negative volunteers aged between 18 and 45 years who are at an increased risk of acquiring HIV. The trial has sites in North America, South America, the Caribbean and Sydney, Australia.According to Dr Tony Kelleher, Clinical Immunologist at NCHECR and the trial’s principal investigator, the investigational vaccine uses a strategy of inducing ‘killer’ T cells.The vaccine uses a disabled version of an adenovirus or common cold virus as a delivery system for synthetic copies of three HIV genes. These genes are designed to prompt the body’s ‘killer’ T-cells, which seek and destroy human cells infected by HIV.In earlier smaller trials, the vaccine generated strong and durable cellular immune responses against HIV. This new trial, known as a ‘proof of concept’ study, will test the concept that the vaccine prevents HIV infection, or results in lower HIV levels in the blood of people who become infected with HIV.”There is no chance that a person can acquire HIV from the vaccine because there is not enough genetic material from the virus within the vaccine to allow an infective particle of HIV to be formed,” says Dr Kelleher. “It is hoped that the outcome of the trial will guide future research and production of at least a partially effective HIV vaccine.”Australia’s peak community AIDS organisation, the Australian Federation of AIDS Organisations (AFAO), supports the trial but the Executive Director, Don Baxter, warns the HIV-affected community against being too optimistic.”The prospective vaccine trial is a great way for Australians to participate in an important international research effort but, right now, condoms used with lubricant are the only significant proven means of protecting yourself from HIV,” Mr Baxter says.Baxter says the complex workings of the human-immune system are still imperfectly understood, even by HIV scientists, so products that look good in preliminary studies can fail.”There is currently no timeline as to when an effective HIV vaccine is expected to be available, so while there are many good reasons to participate in this research, it is important not to have false hopes,” says Mr Baxter.People eligible for the trial will receive a detailed consultation before taking part and will be actively monitored throughout. As the efficacy of the vaccine is unknown at this stage, all volunteers will receive recurrent counselling on how to reduce their risk of acquiring HIV infection.The international trial is being co-sponsored by the Division of AIDS at the US National Institutes of Health and the HIV Vaccine Trials Network in the United States of America.Anyone interested in participating in the trial: contact Rebekah Puls, NCHECR, ph 02 9385 0872.(Source: University of New South Wales: May 2006.)