Hormonal protection from HIV identified in mice
Finding could influence KS treatment
An as-yet unidentified hormone in the urine of pregnant mice appears to protect the animals against Kaposi’s sarcoma and to suppress HIV without toxicity, leading AIDS researcher Robert C. Gallo, MD, revealed recently.
Gallo heads the Institute of Human Virology in Baltimore. He spoke at the annual meeting of the American Association for the Advancement of Science (AAAS) in Seattle.
Gallo refused to give many details about his findings, saying the work is still in the early stages and has not yet been published.
The discovery of the hormone’s protective effects was made by accident during an experiment in Gallo’s lab in which malignant cells were inserted into immune-deficient mice. Unknown to the scientists, the experimental mice were of both sexes. The females became pregnant, and some were found to be tumor-free.
The protective hormone is found in the mouse urine only in the earliest stages of pregnancy, during the first days of the embryo’s life, Gallo reported. "The chemical appears to suppress HIV without toxicity, kill Kaposi’s sarcoma, and promote normal bone marrow growth," he said.
It is similar to but not the same as human chorionic gonadotropin (HCG), a glycoprotein found in the urine of pregnant women that helps the fetus survive.
Gallo said it’s a time for feeling reasonably good about the state of AIDS research. But he emphasized that the prospects for a vaccine discovery are doubtful.
"I believe no one knows if we will ever have a vaccine. But also, it would not be a shock if a vaccine were successful in another five years. There are vaccine candidates out there but we haven’t tried them," Gallo noted.
Gallo says researchers have to overcome four major problems in order to develop a vaccine:
• the variety of forms the virus can assume;
• the high cost of research;
• the difficulties of conducting a clinical trial and of translating the results of animal models to humans;
• the ability of the virus to inject its genes into the cells it infects.
These difficulties have resulted in a declining level of interest among pharmaceutical companies in pursuing AIDS vaccine development, Gallo observed. "Governments will have to take up the slack and not just one government," he said.
Chemokines and their receptors are one promising avenue for researchers to pursue, Gallo says. He cited a case in which 14 hemophiliacs failed to contract AIDS despite repeated exposures. "They all had high levels of chemokines," he noted.
Gallo also insisted that the protease inhibitors and combination therapies now used in AIDS treatment are not a "cure" for the disease. "We don’t know the long-term effects of combination therapies. We don’t know if resistant clones will emerge later. And we don’t know the life span of the cells that harbor HIV," he said.
To qualify as "cured," a person would have to be able to live a normal life span without AIDS symptoms, and after death have no viral sequences in the blood, Gallo stated.
There are no new ideas about AIDS’
He pointed out that the apparent breakthroughs presented at the Vancouver conference on AIDS in 1996 were the result of many years of patient, ongoing basic research.
"There are no new ideas about AIDS," Gallo asserted. "We knew about proteases a long time ago. There has been an ongoing research project to develop a drug that targets steps in the virus pathway. But it takes time for the pharmaceutical industry to develop such drugs, and it takes time to test them."
Gallo also pointed out that few people outside the developed countries are able to get any treatment at all for HIV, or to afford 10 years of drug combination therapies. He said it’s impossible to predict the future rate of AIDS in the population because there are so many different strains of the virus. According to one estimate, 8,500 new people are identified with the disease each day.
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