*EPF112 04/08/2002
Text: Trial HIV/AIDS Vaccine Shows Promise
(Human trials to expand in Britain and Africa) (1360)

Two experimental vaccines against HIV/AIDS have been effective in a small trial conducted by the International AIDS Vaccine Initiative (IAVI), according to an April 4 announcement from the research consortium, funded by the United States government, the Bill and Melinda Gates Foundation and other international donors.

As a result of the initially promising signs, IAVI will launch expanded human testing in Britain. "The goal of this 100-plus volunteer study is to confirm the results of the previous trials as well as investigate different doses and timings of administering the vaccines," according to the IAVI press release.

The 26 volunteers who have taken the vaccine have shown a stimulated response from the immune system, as researchers had hoped. Early stage trials have also been underway in Kenya, though their results have not yet been fully analyzed. Second stage trials are scheduled to begin in sub-Saharan Africa by the end of 2002.

Besides these two vaccines in human trials, IAVI is developing several other prospects. IAVI's Senior Vice President for Research and Development, Dr. Wayne Koff, said, "No one knows the magic recipe for an AIDS vaccine. The surest path is to try multiple approaches at once, comparing them against each other to see which are best."

Following is the text of the press release:

(begin text)

INTERNATIONAL AIDS VACCINE INITIATIVE

Pair of IAVI-sponsored AIDS vaccines for Africa shows promise in initial human trials, progresses to intermediate testing in UK

LONDON, 4 April 2002 -- Having successfully completed first-stage human testing, a pair of vaccines designed to mobilize the immune system to protect against HIV and AIDS today advanced to second-stage trials in the UK. The vaccines are the only in human testing that are tailored for variants of HIV common where the infection rate is highest, sub-Saharan Africa.

The two vaccines-one a naked DNA formulation, the other constructed from a weakened pox virus, MVA-were developed and are being tested by a cross-national partnership that includes the International AIDS Vaccine Initiative (IAVI); the University of Oxford and UK Medical Research Council; and the University of Nairobi and Kenya AIDS Vaccine Initiative. The nonprofit IAVI is financing and coordinating the project, and all partners have agreed that if the vaccines ultimately prove successful, they will rapidly be made available to developing countries at reasonable prices.

These AIDS vaccines are two of more than a half dozen in development with IAVI support. IAVI's strategy is to speed the search for a winner by fast-tracking a diverse portfolio of possibilities.

Trials in the UK

In the UK, the Oxford-Nairobi-IAVI DNA and MVA vaccines entered human trials in August 2000 and since have been tested in 26 volunteers. The vaccines are safe and well tolerated. And the vaccines are stimulating the immune system as they are intended to-eliciting anti-HIV CD8+ T cell-mediated responses as measured by ELISPOT assays.

The next step for these vaccines is intermediate human testing, which has started at Imperial College of Science, Technology and Medicine in London and will soon begin also in Oxford. The goal of this 100-plus volunteer study is to confirm the results of the previous trials as well as investigate different doses and timings of administering the vaccines. If the vaccines continue to perform well, the research partners plan to commence final-stage, multi-year trials within two or three years.

Trials in Africa

Sister studies of the vaccines have been underway in Kenya since March 2001. The data from these trials still are being collected and analyzed and are expected later this year. Second-stage trials of the vaccines are scheduled to begin in sub-Saharan Africa by the end of the year.

The landscape of AIDS vaccine research

"Until very recently, progress in accelerating AIDS vaccine development was terribly slow, because financial and political commitments were lacking," said Seth Berkley, MD, President and CEO of IAVI. "Today, the world is just beginning to make up for lost time. We have a moral and public health obligation to work even faster-each month shaved from when a vaccine is widely available saves more than a half million lives."

"IAVI is accelerating the Oxford-Nairobi DNA-MVA candidates while at the same time aggressively pursuing many other, entirely different designs," said Dr. Wayne Koff, IAVI's Senior Vice President for Research and Development. "No one knows the magic recipe for an AIDS vaccine. The surest path is to try multiple approaches at once, comparing them against each other to see which are best."

By 2007, IAVI plans to move 8 to 12 AIDS vaccine candidates through early human trials and see the most promising two or three into final-stage studies. IAVI-sponsored vaccines are poised to begin testing within the next few years in South Africa, Uganda, India and China, and in Europe and the US.

HIV subtype and vaccination The Oxford-Nairobi-IAVI vaccines are tailored for strains of the virus predominant in east Africa, specifically HIV subtype A. This is significant because HIV's genetic structure differs geographically, and scientists do not yet know the implications of this for vaccination. Because the vast majority of AIDS vaccine candidates are developed for HIV subtype B in the industrialized world, IAVI is committed to filling the pipeline with vaccines for other subtypes common in developing nations and testing them in a number of areas. This will help determine how, if at all, HIV's genetic variation is relevant to AIDS vaccine design.

More about the Oxford-Nairobi-IAVI DNA and MVA vaccines

The Oxford-Nairobi-IAVI vaccines aim to protect HIV-uninfected individuals from AIDS. They are built to train the immune system to produce cells that can seek out and destroy other cells in the event that they are hijacked by HIV-this is called cell-mediated immunity. The idea is that a vaccinated individual who later comes into contact with HIV would have a strong army of immune cells ready to quarantine and choke off the virus before it could make permanent inroads.

The inspiration for this approach comes from a number of studies, among them a small group of commercial sex workers in Africa. These women, despite repeated exposure to HIV through sex without condoms, resisted contracting the virus for years. "Some women may have been protected from HIV by a natural ability to use cellular immunity to thwart infection. We are optimistic that our vaccines will be able to stimulate this defense in others," said University of Nairobi Professor Dr. J.J. Bwayo, who is leading trials of the vaccines in Kenya.

Both vaccines are constructed from copies of selections of HIV's genes. Because of this, there is no chance that the vaccine can cause AIDS, as the ingredients to form a functional virus are missing. For the naked DNA vaccine, HIV genes are stitched into a ring of DNA. For the MVA vaccine, the same genes are inserted into modified vaccinia Ankara (MVA), a virus unrelated to HIV. MVA is altered so it does not cause disease. Doses of the DNA and MVA vaccines for testing were produced by, respectively, manufacturers Cobra Pharmaceuticals Ltd. (UK) and Impstoffwerk Dessau Tornau (IDT, Germany).

The vaccines are designed to be used in a prime-boost combination, with the naked DNA formulation administered first and the MVA vaccine given second.

About IAVI

The International AIDS Vaccine Initiative (IAVI) is a global nonprofit organization working to speed the search for vaccines to prevent HIV and AIDS and help guarantee that future vaccines will be rapidly available to all. IAVI's focus is AIDS vaccines for developing countries, where 95% of the nearly 15,000 new HIV infections daily are occurring. IAVI's major financial supporters include the Bill & Melinda Gates Foundation; the Starr, Rockefeller and Sloan foundations; the World Bank; BD (Becton, Dickinson and Company); and the governments of the Netherlands, United Kingdom, United States, Canada, Ireland, Denmark and Norway. IAVI was founded in 1996 and is a collaborating center of the Joint United Nations Program on HIV/AIDS (UNAIDS).

(end text)

(Distributed by the Office of International Information Programs, U.S. Department of State. Web site: http://usinfo.state.gov)

Return to Public File Main Page

Return to Public Table of Contents