News and Research
Immune System
Studies Offer New Insight Into HIV Vaccine Development

2-17-2004
MADISON -- Mutations that allow AIDS viruses to escape detection
by the immune system may also hinder the viruses' ability
to grow after transmission to new hosts, scientists at the
University of Wisconsin-Madison announced this week in the
journal Nature Medicine.
The
discovery may help researchers design vaccines that exploit
the notorious mutability of HIV by training the immune system
to attack the virus where it's most vulnerable. The work
appears alongside a study of HIV-infected people performed
by scientists at Harvard Medical School and Oxford University.
The Wisconsin study's lead author, Thomas Friedrich, is
a doctoral student working under the direction of David
Watkins, professor of pathology at UW-Madison and senior
scientist at the Wisconsin National Primate Research Center.
Watkins'
team produced an "escaped" AIDS virus that mimicked
events that occur in HIV infection when the virus mutates
to become unrecognizable to killer cells known as cytotoxic
T-lymphocytes, or CTL. The researchers found that the mutant
virus did not grow as well as the original strain. The mutations,
while allowing the virus to escape immune recognition, had
also weakened the virus. To model the transmission of escaped
viruses between people, the team inoculated monkeys with
the mutant virus strain. They discovered that most of the
escape mutations were lost as the virus grew in the monkeys,
often restoring original sequences that killer cells could
recognize.
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Some scientists have theorized that HIV could adapt
to the human immune system as the AIDS epidemic develops, becoming
less and less recognizable. Watkins said that his group's findings
should help allay these fears.
The UW-Madison group has been studying immunity to
AIDS viruses since the early 1990s. Most recently, the researchers
have been studying the ways in which viruses mutate to "escape"
recognition by the body's killer cells. Killer cells are white blood
cells that perform immune "surveillance" throughout the
body, detecting infected cells and eliminating them before the virus
can spread.
"Over 40 million people are now infected with
HIV worldwide, and a vaccine is urgently needed," Watkins said.
"We hope that our findings can be used to help design vaccines
that show killer cells how to fight the virus most effectively."
This story has been adapted from a news release issued
by University Of Wisconsin-Madison, www.wisc.edu.
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