AIDS Immunization Technique Reported Safe : Testing Expanded at USC on Method Developed by Salk
Preliminary trials of an AIDS immunization treatment developed by Dr. Jonas Salk, the polio vaccine pioneer, show the technique appears to be safe, and as a result, expanded trials have begun at USC Medical School to determine whether the approach can help prevent the deadly disease, the researchers are reporting today.
Salk and Dr. Alexandra Levine, the principal investigator, said in an interview Tuesday that the initial results in nine patients who were infected with the AIDS virus but had not yet developed AIDS showed considerable promise for further research. The trials were being expanded to include about 60 more individuals, they said.
The researchers stressed that their findings thus far dealt primarily with the lack of toxic side effects from the treatment. And they cautioned that “no claim whatsoever” of effectiveness was indicated at this time.
“We have a method, not a product,” Salk said.
The new findings from USC’s Kenneth Norris Jr. Cancer Hospital are expected to generate widespread discussion when they are presented today at the fourth international conference on AIDS.
Inactivated Virus Particles
The treatment involves injections of AIDS virus particles that have been killed or, in scientific parlance, inactivated. The goal is to boost an infected individual’s immune system and forestall further damage that could trigger the acquired immune deficiency syndrome.
The treatment is not being tested as a vaccine for uninfected individuals, although Levine said this is “where we hope to go” if the current trials are successful.
The use of human immunodeficiency virus (HIV) particles sets the Salk approach apart from other AIDS immunization therapies and has been a source of scientific controversy. Although some scientists feel the approach has considerable merit, others have expressed concerns that the injections might stimulate AIDS virus production instead of decreasing it.
The results to date show that neither virus stimulation nor further immune system damage occur, the researchers said.
The key to the new approach, in Salk’s view, may be the long period of time--an average of about seven years--between when people become infected with the virus and when they become ill with AIDS. He believes that the body initially can ward off any damage to the immune system caused by the virus. AIDS only develops, according to this theory, when the immune system is finally worn down.
Tests on Chimpanzees
The inactivated virus particles are prepared by exposing live viruses to radiation and intense sound waves and to freezing and thawing techniques, Salk said. The safety of this material and its ability to produce a strong antibody response have been extensively tested in chimpanzees.
In the process, a key protein on the surface of the virus is destroyed. The loss of this protein, called gp-120, may increase the safety of the preparation because the protein that is removed plays an important role in the ability of the virus to invade human immune system cells.
According to Levine, a USC professor of medicine and executive associate dean, the first nine patients studied all had the human immunodeficiency virus in their bloodstreams.
Each of the nine patients received an initial inoculation of the inactivated virus particles and a booster shot about three months later. The patients have been followed for an average of six months.
None of the nine has evidence of toxic side effects from the injections, Levine said. One developed a “mild case” of the AIDS-related pneumonia called Pneumocystis, which was successfully treated.
‘All Working Full-Time’
She added: “The others have remained very well. They are all working full-time. I make no claim whatsoever of any therapeutic affect in that regard, but the fact is that they are well.”
Seven of the nine patients also had evidence of strengthened general immunity, as measured by so-called skin tests that determine the ability of the body to mount an immune response to the small test injections of foreign proteins. (The test is similar to a commonly used skin test for exposure to the tuberculosis bacteria.)
After the initial injection, the AIDS virus could no longer be detected in the blood of five of the nine patients. This may also indicate strengthened immunity, according to Levine. But after six months, only one patient has remained virus-negative.
Levine said this may have been due in part to the fact that all nine were severely immune-deficient and “on the verge of developing AIDS.” She said the reappearance of the virus indicated a need to expand tests to infected individuals whose immune systems are “more intact” to begin with.
As a result, the USC study is being expanded to test a series of three injections in an additional nine patients similar to those already on therapy, and to 54 patients in the early stages of viral infection. Half of these patients in the latter group will receive injections and the other half will not, Levine said. Comparisons between the two groups will allow the effectiveness of the treatment to be assessed.
UCLA researchers reported condom failure rates more than double those uncovered by the FDA. (View, Page 1).
