AIDS vaccine shows promise in human trials
An AIDS vaccine developed by an Emory scientist has proven safe in human trials and, even at low doses, is stimulating the kind of immune response in people that protected primates in earlier studies.
The first phase of the human trials, which began in April 2006, was intended to provide primarily safety information. But blood tests performed at the Emory Vaccine Center revealed that six of the eleven participants had anti-AIDS immune responses. “Two of the participants are likely recipients of a placebo. Thus, we have an outstanding response rate for a dose that was not necessarily expected to elicit a response,” says the vaccine’s creator, Harriet Robinson, chief of microbiology and immunology at Yerkes National Primate Research Center.
The DNA-based vaccine, which consists of prime followed by two boosters, uses a genetically engineered smallpox virus to spur the production of T cells—white blood cells responsible for fighting off infection. The vaccine tested well in rhesus macaque monkeys at Yerkes: it did not prevent infection with the AIDS virus, but the animals receiving the vaccine remained healthy and suffered no immune damage from the virus.
On the basis of the vaccine’s most recent success, a more extensive second trial is being moved forward, conducted with support from the National Institutes of Health (NIH). “It’s exciting, but I do feel a bit like Jacob wrestling with the angel as we put these trials together, trying so hard to get it right,” Robinson says. “You don’t get to do the big trials twice.”
The vaccine was developed at GeoVax Labs, a biotechnology company that spun off from Emory’s AIDS Research Center.
“We’ve been extremely encouraged and pleased with the results we’re seeing at one-tenth the normal dose,” says GeoVax President and CEO Don Hildebrand, a microbiologist. “Now we see the potential for even better immune responses at the stronger dosage.”
The virus Robinson and her colleagues are squaring off against is the most lethal infectious disease in the world: AIDS has killed about twenty-five million people globally since 1981. Some 14,500 new AIDS cases are reported each day, according to the NIH.
Scientists around the world are conducting more than a dozen trials of various AIDS vaccines concurrently. Several of the vaccines have shown promise. “Ten years ago, scientists wanted to have a vaccine by 2007,” says Robinson. “While we won’t make that deadline, I feel that we will likely have one by 2017.”—M.J.L.
Center of Hope
The Emory Vaccine Center, directed by immunologist Rafi
Ahmed, has nearly forty faculty
members from across the University and is one of the largest academic vaccine centers in the world. Established ten years ago, the center’s primary focus is on finding an HIV/AIDS vaccine, although it also is working on vaccines for hepatitis C, malaria, influenza, and other infectious diseases, as well as methods for fighting cancer.
Professor of Pathology Eric Hunter is codirecting an National Institutes of Health-sponsored initiative to develop a second-generation HIV vaccine and a needle-free delivery method.
To conduct clinical studies of promising new vaccines, Emory created the Hope Clinic in downtown Decatur in 2002. Last year, the center recruited director Mark Mulligan, who founded the Alabama Vaccine Research Clinic at the University of Alabama at Birmingham and headed the first clinical study of Professor Harriet Robinson’s vaccine. The clinic is expanding its focus to include other emerging infections, such as avian flu, West Nile virus, SARS, and Ebola.
“In many ways, Atlanta is a mecca for an infectious disease academician,” Mulligan says. “The combination of Emory, the CDC, and a population of 4.5 million in the metro area makes this a very exciting place to come to work.”
The Hope Clinic (www.hopeclinic.emory.edu) was recently named an HIV Vaccine Trials Network site for the NIH. “We have been very pleased with the depth of volunteer support we have seen in Atlanta,” says Professor of Medicine Carlos del Rio.—M.J.L.