The enemy. a new vaccine counteracts HIV virus as in monkeys.
a study in this week's issue of science showed that a new AIDS vaccine can protect monkeys from getting sick, providing new avenues for AIDS vaccine human. But experts warn that many barriers remain high, and there are currently no plans to move the experimental vaccine in human trials.
The study, led by Norman Letvin and Dan Barouch of Beth Israel Deaconess Medical Center in Boston, in collaboration with Merck Research Laboratories in West Point, Pennsylvania, combines several high-tech concepts. The heart of the vaccine is a bacterial DNA fragment, called a plasmid, which can carry genes from other organisms. genes contained a plasmid encoding SHIV proteins, a combination of HIV and simian cousin, SIV concocted laboratory. In addition, the researchers created another plasmid encoded a messenger of the immune system, interleukin-2 (IL-2), attached to a piece of an antibody, or immunoglobulin (Ig). This protein, the researchers hoped, would rev the immune response of the vaccine.
When challenged with a relatively high dose of SHIV which rapidly destroys the immune system in apes, animals that received the vaccine developed a fictitious disease or died within 140 days. The monkeys that received the DNA vaccine and IL-2 / Ig plasmid, however, fared better. All had an intact immune system and low levels of SHIV in their blood after 140 days
The researchers also added new fuel to a long-standing debate on the power of antibodies against another warrior, immunological killer T cells. In the early days of vaccine research against AIDS, almost everyone in favor of vaccines aimed to stimulate antibody. More recently, the killer T cells have become the preferred goal. This experiment showed that the killer T cells played the main role in the control of SHIV infection in monkeys.
"The study is very carefully done, and the results are as good or better than anything tried in experimental settings," said Ronald Desrosiers Central New England Regional Primate Research in Southborough, Massachusetts. But no should get their hopes up too high, he added. Desrosiers, whose laboratory first protected monkeys clean with a vaccine against AIDS 11 years ago, said that "we need to be careful to remember that these are optimized laboratory parameters. "
There are other obstacles, too. Interleukin-2 may have serious side effects and if used in the wrong dose, could hinder an effective immune response, says Emilio Emini, head of vaccine against AIDS researcher at Merck. Merck currently has a single DNA vaccine in a small human study and does not intend to test this more complex vaccine in humans.
Furthermore, notes Letvin, experience "challenged" the monkeys with a strain of SHIV that is identical to the DNA vaccine - a very artificial scenario. In the real world, vaccinated people would face a wide range of HIVs. Letvin but stressed that the point of the study is to demonstrate that a vaccine can accomplish if it powerfully stimulates killer T cells. "It is way short of our ultimate goal, but until we reach that, this is a good place to be," says Letvin.
Related Sites
NIH vaccine against AIDS
the International AIDS vaccine Initiative
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