HEALTH-FRANCE: Some Success Found Against AIDS

By Julio Godoy Reprint | | Print |

Julio Godoy

PARIS, Feb 17 2003 (IPS) - French scientists claim at least partial success in developing a vaccine against HIV.

"This is a world first," Michel Kazatchkine, director of the Paris-based National Agency for Research on AIDS (ANRS, after its French name) announced last week. "For the first time in the clinical history of AIDS (Acquired Immune Deficiency Syndrome), we have stimulated a positive immunological reaction against HIV (Human Immunodeficiency Virus)."

Scientists say the vaccine is able to reactivate the immunological system of some people who have HIV.

Patients who received the vaccine in experiments carried out last year were not cured of AIDS, Kazatchkine said. "We cannot use this term because it would mean that we have eradicated the virus," he said.

The results nevertheless are "extremely encouraging," Kazatchkine said. "We know that some HIV positive patients can naturally develop immunity to the virus. But our experiments show that the number of people developing these defences rises dramatically with the aid of the vaccine."

Traditional vaccines are used to "prime" a person’s immune system before a possible infection. Therapeutic vaccines attempt to "teach" a person’s immune system to fight a virus long after it has infected them.

The current treatment of AIDS is combination therapy in which drugs are given to block the replication of HIV in the blood. This can prolong lives, but has strong side effects.

The French experiments carried out in two hospitals last year involved adminstering the vaccine, temporarily called Alvac, to some patients and comparing their response to patients not given the vaccine.

In one experiment at the La Pitié hospital in Paris, 48 HIV positive patients received four injections of the vaccine at intervals of a month. The patients continued their normal treatment against AIDS.

A month after the last injection of Alvac, the patients stopped their combination therapy. "More than 60 per cent of the patients developed defence against HIV," says Christine Katlama, who coordinated the experiments at La Pitié. "We could wake up the patients’ immune system and block reproduction of the virus."

Eighty per cent of the patients had to be given combination therapy again.. But ten of the 48 patients not yet taking it show only a low level of viral infection, says Katlama.

In the second experiment carried out at the Henri-Mondor hospital in Créteil just outside Paris, half of 70 patients on combination therapy were also given Alvac. After nine months of treatment, 63 of them stopped taking drugs.

Among these, 25 per cent who had been given the vaccine had rebuilt their immune system, and could temporarily give up combination therapy. Only five per cent of the patients who had not been given the vaccine could develop a defence against HIV.

Kazatchkine said a 100 per cent effective vaccine could be developed within the next five years. "I hope that after seeing our results the pharmaceutical industry will invest in the development of the vaccine, and help us realise this dream."

Kazatchkine is cautious about development of a preventive vaccine. "That is much more complicated," he says. "Colleagues working on it believe that a preventive vaccine won’t be ready before 2015."

The World Health Organisation says some 42 million people around the world are infected with HIV, 29.4 million of them in sub-Saharan Africa. About 3.1 million people have died of AIDS since it broke out in the early eighties.

Experts say that the HIV virus must ‘hijack’ a cell in order to reproduce.. The viruses are like a brain without a body and they need to take over a cell to make new viruses.

Viruses hide their DNA, the blueprint of every living organism, in the DNA of the cell they infect. When this cell makes new proteins like any other cell, it produces new viruses as well. HIV infects cells mostly in the immune system.

Many cells have proteins on their surface named CD4 receptors. HIV searches for cells with such receptors because this protein enables the virus to bind to the cell. Once the HIV virus does that, it hides its own DNA inside the DNA of the cell, and this leads to multiplication from the hijacked cell.