United Press International - 2 February 2001
Reported by Joe Grossman in Santa Cruz, Calif.

This study in humans will be the first of a vaccine specific for the type of HIV -- clade A -- common to much of Africa, the continent hardest hit by the AIDS epidemic. The vaccine, if effective, will protect healthy people from infection with the human immunodeficiency virus, which causes AIDS.

Researchers from the University of Nairobi, Kenya, and Radcliffe Hospital in Oxford, England have already injected about 20 volunteers in Oxford. Volunteers in Kenya will join the study in a few weeks.

In another first, the vaccine's components have never been tried before in humans.

Oxford immunologist Andrew McMichael, about to catch a plane to Kenya, told United Press International from his home in England that the trial is "one of the first specifically aimed at the T-cell immune response rather than antibodies."

Until recently, most HIV/AIDS vaccines have focused on the immune system's antibody response to fragments of the HIV virus, not the cell-mediated response of which killer T cells are a part.

The new vaccine has pieces of HIV genetic material believed likely to stimulate production of T cells that are HIV-specific. Intended for healthy, previously unexposed people, it was created at Radcliffe Hospital's Human Immunology Unit at the Institute of Molecular Medicine.

The DNA fragments have been fabricated synthetically and strung together like beads on a string for inclusion in the vaccine -- a biotechnological innovation, researchers said. It would be impossible to contract AIDS from the vaccine, they added.

J.J. Bwayo, chairman of the medical microbiology department at Nairobi University, spoke to UPI from his laboratory: "The development of the vaccine dates back to1985 when we started to study a (group) of female commercial sex workers in Nairobi. During follow-up, we found out that a small percentage, 5 percent of the women, remained uninfected, even though they continued to be exposed to HIV."

The uninfected women had developed very high numbers of killer T cells, a crucial component of the immune system, Bwayo told UPI. This observation contributed to the decision to create a vaccine designed to boost T cell numbers.

Two successive and different doses of the vaccine will be given. The first injection contains the string of HIV DNA and is designed to alert immune system helper T cells to stimulate HIV-specific killer T cells to multiply.

In the second injection, a few months later, the string of HIV DNA is put inside a specially modified vaccinia virus, called MVA, to mimic a real viral attack. This shot is designed to boost the number of killer T cells specific for HIV, affording an individual protection from infection if exposed to HIV.

"It will be the first time that somebody has done a DNA and MVA (vaccine) in humans," Harriet Robinson, chief of microbiology and immunology at the Yerkes Research Center at Emory University told UPI.

AIDS vaccine trials were first attempted 14 years ago. Approximately 50 vaccines have entered phase I, trials that emphasize testing the safety, not efficacy, of a drug. About five vaccines have qualified or are imminent for the dosage evaluation phase II. One vaccine has reached phase III, in which the vaccine is experimentally given to a large at-risk population.

Dr. Bwayo told UPI, "It's a long process. We're not saying anything less than 5 to 10 years."

Much of the Nairobi/Oxford research is supported by the International AIDS Vaccine Initiative, which is giving 4.5 million dollars over a 3-year period.

IAVI's major funding source is the Bill and Melinda Gates Foundation, which recently pledged $100 million. Margaret Liu, senior advisor for vaccinology to the foundation, told UPI she was concerned about the effective delivery of a vaccine to those most in need, should researchers successfully develop such a vaccine.
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