By Sean Henahan, Access Excellence

VANCOUVER (July 11,'96) While significant improvements are being achieved in the AIDS treatment area, vaccine research continues to languish. Researchers hope a new global initiative may speed up the search for an effective AIDS vaccine.

There is currently no vaccine in large-scale trials. UN estimates indicate that less than five percent of AIDS research funding is dedicated to finding a practical AIDS vaccine. The most optimistic researchers believe a vaccine is at least five years away.

"It is a joke. There is only one way you are going to stop this virus and that's with a vaccine. We need to do more,'' Donald Francis, a pioneer in AIDS virology at the Centers for Disease Control and now president of Genenvax Inc., told the press a the XIth International AIDS Conference.

The International AIDS Vaccine Initiative (IAVI) represents a collaborative effort of world health bodies and leading research institutions. The IAVI is now ready to funnel millions of dollars into AIDS vaccine research and development worldwide.

"A vaccine is possible, and it is essential -- yet we won't have a vaccine until we change the way the world thinks about AIDS vaccines," said Dr. Seth Berkley, chairman of the IAVI interim board of directors and associate director of health sciences for the Rockefeller Foundation. "The current vaccine development effort is inadequate."

Although there is no cure for AIDS, many in the scientific community believe that an AIDS vaccine is possible, notes Margaret Johnston, Ph.D., IAVI's scientific director: "Throughout history, vaccines have been the only proven way to stop the spread of deadly viruses. It only makes sense to me that we push hard for a vaccine for HIV/AIDS, given the devastation the disease is causing."

"Vaccines have eliminated smallpox and halted polio and measles in many parts of the world," she added. "With the proper vision, scientific agenda and global coordination, we can focus some of the best minds in the world on developing a vaccine for AIDS -- something that I believe we can achieve in my lifetime."

"Each new scientific discovery about the underpinnings ofHIV/AIDS is reason to be optimistic," said Johnston. "The more we know about how HIV works, the more likely we can use this knowledge to help find a vaccine."

"We've seen encouraging results of vaccine research in animal models, as well as promising human evidence. For example, we know that some people are able to live with HIV infection for long periods of time without getting sick. Others seem to develop a type of natural resistance to the virus, despite repeated exposures. And, we've seen babies born to HIV-infected mothers who are able to clear the infection. As we learn why these things happen, we can use this information to help move AIDS vaccine development along," she said.

Increasing the scope and number of human AIDS vaccine trials, coupled with state-of-the-art laboratory research, will be key to success, Johnston said .

The IAVI plants to devote considerable resources to the needs of developing countries, a decision welcomed by Dr. Peter Piot, executive director of UNAIDS. "According to UNAIDS estimates, about nine-tenths of the 8,500 people a day who contract HIV infection live in a developing country. A vaccine is the main hope for populations exposed to a daily risk of this magnitude."

"A vaccine is key to a safer world for all. Given the current scale of global travel, if we manage to bring down the dangerously high levels of HIV in Africa, Asia and Latin America with the help of a vaccine, all of us will benefit," he noted.

Research in the AIDS vaccine area has not come to a standstill. The AIDS Vaccine Evaluation Group (AVEG) has studied 16 candidate vaccines, 12 adjuvants, six vectors, and seven delivery routes, reported Barney Graham of Vanderbilt University School of Medicine.

While past research was mostly focused on candidate vaccines built around the HIV envelope protein gp120, the emphasis now is likely to be on the use of new vectors such as canarypox carrying env, gag or pol antigens, he said.

Vaccine developers also have to consider a host of ethical and practical issues when contemplating large vaccine trials. Such trials are expensive to run and difficult to follow-up. The US government essentially washed it hands of AIDS vaccine trials in 1994 when it announced it would not support trials of the gp120 vaccine in the US. Plans are now underway to conduct a large trial of this vaccine in Thailand, a country that has seen an explosion of new AIDS cases in recent years.

Vaccine research has not stopped completely. Indeed, the AIDS Vaccine Evaluation Group (AVEG) has evaluated 16 candidate vaccines, 12 adjuvants, six vectors, or "delivery vehicles" for vaccines, and seven delivery routes in recent years, reported Barney Graham of Vanderbilt University School of Medicine.

While most research has focused on recombinant vaccines built around the HIV envelope protein gp120, the focus of research now seems to be on testing new vectors such as canarypox carrying env, gag or pol antigens, he said.

Whereas early vaccine strategies relied on generating an antibody response to HIV. It soon became apparent that HIV could quickly get around this approach by mutating at a phenomenal rate. The vector approach in contrast, utilizes a bacterial or viral vector to carry selected HIV genes into cells, initiating what is hoped would be a protective immune response against future infection. This approach is being supplemented with a booster strategy, wherein patients would receive a booster of an antibody-producing vaccine such as GP-120 to complement the cellular immunity generated by the vector-based vaccine.

Other researchers argue that more basic research is required before a really useful vaccine can be developed. They point out that there is a great lack of information on such basic questions as how exactly HIV infects the body and how it spreads. Questions also remain on how or whether HIV is infectious from within and between cells. The researchers not that without a good fundamental understanding of the routes and mechanisms of infection, it will be difficult to develop a vaccine.

Current information on AIDS and AIDS Vaccine Research