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New information on HIV/AIDS out soon

By Vision Reporter

Added 20th January 2002 03:00 AM

Scientists will on Thursday report encouraging progress but also a cruel setback in the quest for a vaccine to fend off HIV.

Scientists will on Thursday report encouraging progress but also a cruel setback in the quest for a vaccine to fend off HIV. They have found that monkeys injected with an experimental vaccine can suppress the AIDS virus in their bodies to remarkably low levels — but the virus that survived can apparently mutate and sidestep the treatment. The studies, conducted by a team led by Emilio Emini of Merck Research Laboratories in West Point, Pennsylvania, and another led by Dan Barouch of Harvard Medical School, Boston, are published in Nature, the British science journal. Since it was first identified 20 years ago, AIDS has killed more than 20 million people and another 40 million are currently infected with HIV, yet the desperate search for a vaccine has borne no fruit. One reason for this is the broad and shifting range of HIV strains, which makes it hard to generate a classic vaccine based on antibodies — the defensive proteins produced by B lymphocyte blood cells, which are trained to spot and destroy a known bacteria or protein. The Emini team, tested three kinds of vaccines based on stimulating bigger defences — cytotoxic T lymphocytes (CTLs) that are able to home in on and destroy virus-infected cells. The vaccines used different transport systems to infiltrate cells around the body, each carrying tiny pieces of genetic material. This DNA expressed a protein that, hopefully, would prime a response from the CTLs when macaque monkeys were injected with SHIV — a hybrid version of HIV and its simian relative, SIV. One of the vaccines was a disabled virus, called adenovirus type 5 (Ad5), which carried the DNA in it like a Trojan horse; the second, based on the same principle, used a harmless virus once used in smallpox vaccination; the third, called a plasmid DNA vaccine, was a genetic chunk of the virus itself. None of the monkeys was able to repel infection, which as in the famously effective case of the smallpox and polio vaccines, is the ultimate dream of vaccine engineers. However, monkeys that had been injected with the Ad5 vaccine or had received a booster jab of the DNA vaccine did astonishingly well. AFP

New information on HIV/AIDS out soon

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