HOW much better would it be if a simple injection could free HIV-positive people from having to take costly antiviral drugs for the rest of their lives. The virus鈥檚 knack of hiding from the immune system has meant that a vaccine to suppress HIV infection has always seemed a distant prospect. Now researchers say they have evidence that a vaccine containing beefed-up immune cells might give the body a real shot at destroying the virus.
In test-tube experiments, Charles Rinaldo of the University of Pittsburgh Medical Center in Pennsylvania and colleagues loaded up immune cells known as helper T-cells with HIV and then waited for the virus to kill the cells. The remains of the dead cells 鈥� including the specific proteins that HIV coaxed them to produce 鈥� were then fed to dendritic cells, the cells at the front line in immune defence, which pick up distress signals emitted when cells in the body die. In other words, the method uses the helper T-cells as a factory for producing HIV proteins. The souped-up dendritic cells then present the HIV proteins to killer T-cells, priming them to better detect 鈥� and destroy 鈥� the virus.
Previous attempts to vaccinate against HIV involved injecting patients with dendritic cells loaded with an inactivated form of the virus. Using helper T-cells to produce HIV proteins is better, Rinaldo says, because dendritic cells seem to handle the proteins more easily than the whole virus. 鈥淲e鈥檙e trying to come as close as we can to nature鈥檚 own methods.鈥�
Advertisement
Rinaldo鈥檚 team has tested a similar approach in a trial in which 18 HIV-positive individuals were injected with HIV proteins to supercharge their dendritic cells. Although the trial was conducted to test safety rather than efficacy, the volunteers showed improved immune system activity within six weeks of receiving the HIV proteins.
The researchers expect to receive approval from the US Food and Drug Administration by the end of the year to carry out a trial in which each patient鈥檚 dendritic cells are removed and fed HIV protein fragments in the lab. These specially trained dendritic cells will then be reintroduced into the patient.
鈥淭his approach might one day make the body鈥檚 immune system so good at fighting HIV it would no longer need drugs鈥�
The hope is that this personalised approach might one day make the body鈥檚 immune system so good at fighting HIV that it would no longer need the help of antiviral drugs. 鈥淥bviously if you could control the virus with a therapeutic vaccine instead of a lifetime of antiviral drugs, that could translate into a substantial reduction in side effects and a cut in cost,鈥� Rinaldo says. 鈥淯ltimately what we鈥檙e after is very little drug therapy or no drug therapy.鈥� The team presented the results of their work at the 16th International AIDS Conference in Toronto, Canada, this month.
Jean-Marie Andrieu of the Institute of Research for Vaccines and Immunotherapies for Cancer and AIDS in Paris, France, says the approach is promising. Andrieu, however, favours feeding HIV directly to dendritic cells. He fears that using the helper T-cells could create the wrong immune response, because proteins do not affect dendritic cells in the same way as HIV.
Joseph Nkolola of the Harvard School of Public 午夜福利1000集合 in Boston says the method would be prohibitively expensive to get up and running. However, he recognises that if it does eliminate much of the need for people to be given antiviral drugs, it could prove cost effective in the long term.
