A pilot study of a live vaccine against the monkey version of the AIDS virus may facilitate such fear about vaccines: that they should never be used newborns. The results in the January of Nature Medicine , have prompted some AIDS researchers to suggest that a live vaccine for humans - an idea shelved because of security concerns - . Should get another look
a team led by virologist Ronald Desrosiers of the New England Regional Primate Research Center injected 18 macaque monkeys born with a genetically weakened strain of simian immunodeficiency virus (SIV). Previous studies have shown that large doses of SIV vaccine protected adult monkeys, but have caused disease in newborns. The new study, which explored the effects of five doses 300 times smaller, found that only infants exposed to higher dose of attenuated virus - 283 nanograms - came down with the disease
Results are. perplexed, because conventional wisdom was that the progression of SIV infection in a wholly disease is unrelated to the initial viral dose. The experience of the New England group "can be taken as evidence of a dose effect, which is hard to explain," said AIDS researcher David Montefiore of Duke University. But the results suggest that the SIV vaccine may be safe and effective in newborn monkeys and adults, says Desrosiers. "Yes, a high dose of the virus in an absolute newborn in extreme conditions can still result in the disease," he said. "But we do not think this is a natural scenario."
Live vaccines supporters mitigated against HIV face an uphill battle to convince their colleagues that the benefits of this approach outweigh the potential risks, however. These vaccines, like the one against polio, carry a risk of causing illness: Each year, about 10 people contract polio vaccine. However, live attenuated vaccines against HIV "bear serious attention," said Michael Murphey-Corb Regional Centre Primate Tulane in Los Angeles. "After all these years of hard efforts," she said, "it's the only thing that we have in our favor. "
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