U.S., European, Thai Researchers Discuss Therapeutic HIV Vaccine Prospects at Emory University Conference
About 150 researchers from the United States, Europe and Thailand on Thursday at an Emory University conference in Atlanta began discussing new opportunities and challenges in developing a therapeutic HIV vaccine, the Atlanta Journal-Constitution reports. Some researchers say that an effective therapeutic vaccine, which aims to prevent the progression of HIV in people already infected instead of preventing transmission of the virus, might be brought to market sooner than a preventive vaccine because HIV-positive people might accept a higher risk of side effects than HIV-negative people, according to the Journal-Constitution. A therapeutic vaccine also would only have to be "partially effective" to allow HIV patients to stop taking antiretroviral drugs, which many people in developing countries cannot afford, according to the Journal-Constitution. "It could have a big impact on the epidemic," Rama Rao Amara, an Emory researcher working on a therapeutic vaccine, said, adding, "It's possible you could take three shots and that would be it."
Current Therapeutic Vaccine Prospects
Some therapeutic vaccines are beginning to "show promise," the Journal-Constitution reports (Wahlberg, Atlanta Journal-Constitution, 5/19). An experimental therapeutic HIV vaccine suppressed the virus in a small group of HIV-positive Brazilians for up to a year, according to a study published in the December 2004 issue of the journal Nature Medicine. Jean-Marie Andrieu and Wei Lu of the Institut de Recherche sur les Vaccins et l'Immunothérapie des Cancers et du Sida in Paris led the research, administering the vaccine to 18 HIV-positive Brazilians who had never taken any antiretroviral drugs. Four months after their first immunization, the patients' viral load levels were reduced by a median of 80%, and at the end of one year eight of the patients had viral load levels that were 90% lower than their baseline levels. Every two weeks, the patients received injections that contained a mixture of their own dendritic cells -- a type of cell that is in the first line of defense in the immune system -- and chemically inactivated, whole HIV. The goal of the vaccine is to stimulate dendritic cells to recognize and mark the virus in order to mount a more effective immune response. However, the vaccine currently is impractical to deliver to large numbers of people because it essentially is custom-made for each patient. Andrieu estimated that the cost of the treatment for one year could be $4,000 to $8,000 per person (Kaiser Daily HIV/AIDS Report, 11/30/04). Andrieu and Lu are scheduled to speak at the Emory conference. Small studies by other groups of French and U.S. researchers also have reduced the viral load levels of experimental vaccine recipients, according to the Journal-Constitution. Seth Berkley, president of the International AIDS Vaccine Initiative, said scientists also have identified five "rare" HIV patients who naturally have developed powerful antibodies against many different HIV strains, and researchers are trying to figure out how the patients' bodies generated such a response so it can be duplicated in a vaccine, the Journal-Constitution reports. "We've got the lock, now we have to find the key," Berkley said (Atlanta Journal-Constitution, 5/19).