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US government starts trial of new AIDS vaccine tailored for multiple subtypes of the virus

November 13, 2002

13 November 2002--The Dale and Betty Bumpers Vaccine Research Center (VRC) of the US government's National Institute of Allergy and Infectious Diseases has announced the start of human testing of a new investigational vaccine to protect people uninfected with HIV from contracting the virus or developing AIDS.

The year-long trial will enroll 50 volunteers in the Washington, DC, area. Volunteers must be HIV negative and between the ages of 18 and 40. More information on participating is available at www.clinicaltrials.gov or +1 866 833 LIFE (+1 866 833 5433; toll free when dialed from the US).

Pending promising results from this initial Phase I study, which is designed to assess the vaccine's safety but not whether it is effective, VRC plans expanded trials throughout the US as well as in South Africa and Haiti, in conjunction with the HIV Vaccine Trials Network. Before any vaccine can be licensed as safe and effective, it must pass three phases of human testing, typically requiring at least five to seven years total. No AIDS vaccine has yet done this.

The vaccine is built from technology called naked DNA, in which pieces of HIV genes are stitched into a ring of DNA. The idea is for these genes to stimulate the immune system to develop defensive capabilities against the virus--so that in the event a vaccinated individual is later exposed to HIV, he or she can fight off infection or AIDS. However, by themselves, these genes cannot form a functioning virus, so there is no chance of the vaccine itself causing HIV/AIDS.

There are other investigational AIDS vaccines in human testing that use naked DNA, as well as other technologies. What makes the latest vaccine from VRC unique is that it incorporates genetic material from three subtypes, or regional variants, of HIV.

Specifically, the vaccine contains genes from HIV subtypes A, B and C. Subtype A is prevalent in east Africa; subtype B is common in North America, Europe and parts of Latin America; and subtype C is found most in southern Africa and large sections of Asia. (HIV subtype is sometimes called by its more technical name, clade.)

To be sure, it is not clear if HIV subtype matters for vaccine design, this is, whether it will be possible for a single AIDS vaccine to be effective worldwide, or if subtype-specific vaccines will be needed. As far as existing vaccines for other diseases, both scenarios have played out. For example, viral subtype matters for vaccines against influenza, but not for those against hepatitis B.

Yet the only way to know the implications of HIV subtype is to construct vaccines for a variety of subtypes and test them in a variety of areas. To date, the majority of candidates tried in humans have been built only for HIV-B. Morevoer, the VRC vaccine is the only now in human testing that incorporates material from HIV-C, the subtype prevalent in the hardest-hit areas of southern Africa and the emerging epidemics of India and China. IAVI is sponsoring the development of other HIV-A and HIV-C vaccines, one of which (subtype A) is now in human testing, with the others scheduled to begin in 2003 or 2004 (subtypes A and C).

"IAVI applauds the Vaccine Research Center and the US government for their innovative work that hopefully will add to our knowledge about the pressing question of what HIV subtype means for vaccines," said Seth Berkley, MD, President and Chief Executive Officer of IAVI. "If this candidate vaccine indeed proves promising in early trials, it must be accelerated into additional testing, alongside many others. We all must do everything possible to find the world a preventive AIDS vaccine quickly."