New AIDS vaccine shows great potential

It has eluded scientists for nearly half a century. It has been one of the biggest issues in the medical field. And now, in a Thailand laboratory, a significant step has been taken in prevention of acquired immune deficiency syndrome (AIDS): Scientists have developed a vaccination that shows more potential in preventing AIDS than ever before. The experimental process was the largest and most expensive AIDS research project ever conducted. With 16,000 participants, the entire process cost a total of $105 million. The study began six years ago, and only now has it reached a palpable conclusion.

According to the National Institute of Allergy and Infectious Diseases, one of the organizations that conducted the study, the experiment tested a new type of vaccination known as RV144. In the two experimental groups — one of which received the vaccination while the other received a placebo — the vaccinated participants contracted AIDS at almost one-third the rate of the control group. The participants consisted of individuals aged 18–30 from several provinces near Bangkok and they were recruited from the general population, rather than from sex workers, drug injectors, or any other high-risk groups.

Gordon Rule, a biochemistry and immunology professor in the biological sciences department of the Mellon College of Science, expressed his pleasure at the discovery. “It’s a big step forward,” Rule said. The RV144 vaccination itself consisted of two separate vaccinations, neither of which worked effectively by itself. “The two different vaccines were directed at two different immune responses,” Rule said. When the immune response recognizes proteins on the surface of the virus as foreign, the body produces antibodies (known as “neutralizing” antibodies). The antibodies attach to the viral proteins and induce the destruction of the cell by macrophages, which engulf and digest the viruses. One of the vaccinations was an injection of proteins found on the surface of human immunodeficiency viruses (HIV). With the injection, more antibodies would be produced, reducing the likelihood of contracting AIDS. Unfortunately, on its own, the protein vaccination did not produce a sufficient number of antibodies.

The second vaccine involves the white blood cell response in the body. There are two types of T cells involved in immune response: helper T cells (Th cells) and cytotoxic T cells (Tc cells.) The Th cells are involved in all aspects of the immune system, including the production of antibodies.

Individuals develop AIDS when the Th cells are infected by HIV. The Tc cell specifically recognizes proteins on HIV and kills them. The second vaccination increases the population of Tc cells in the body, allowing more foreign cells to be identified and killed. This method did not work on its own, however, and researchers speculate that the body’s resources would deplete in the production of Tc cells and cause even more harmful effects. It is important to note that RV144 is not completely protective. The methods involved in vaccinations only offer partially preventive measures, since the vaccination does nothing to lower the level of HIV in the bloodstream after infection. Rule advised, “People shouldn’t be careless.”

Of the future for AIDS research, Rule said, “The first thing I would try to do would be to see if you could boost or enhance the immune response, especially with the Tc cell activation, to see if you could put different HIV proteins on there that would lead to more responsive Tc cells.” He also discussed changing how the vaccinations were applied. “Varying the schedule of when people were vaccinated may improve the response.”