WASHINGTON – The virus that causes AIDS can hide in the bone marrow,
avoiding drugs and later awakening to cause illness, according to new
research that could point the way toward better treatments for the
disease.
Finding that hide-out is a first step, but years of
research lie ahead.
Dr. Kathleen Collins of the University of Michigan and her colleagues
report in this week's edition of the journal Nature Medicine that the HIV virus
can infect long-lived bone
marrow cells that eventually convert into blood cells.
The virus is dormant in the bone marrow cells, she
said, but when those progenitor
cells develop into blood cells, it can be reactivated and cause
renewed infection. The virus kills the new blood cells and then moves on to infect
other cells, she said.
"If we're ever going to be able to find a way to get
rid of the cells, the first step is to understand" where a latent
infection can continue, Collins said.
In recent years, drugs have reduced AIDS deaths
sharply, but patients need to keep taking the medicines for life or the
infection comes back, she said. That's an indication that while the
drugs battle the active virus, some of the disease remains hidden away
to flare up once the therapy is stopped.
One hide-out was found earlier in blood cells called
macrophages. Another pool was discovered in memory T-cells, and research
began on attacking those.
But those couldn't account for all the HIV virus
still circulating, Collins said, showing there were more locations to
check out and leading her to study the blood cell progenitors.
Finding these sources of infection is important
because eliminating them would allow AIDS patients to stop taking drugs after
their infection was over. That's critical in countries where the
treatment is hard to afford and deliver.
"I don't know how many people realize that although
the drugs have reduced mortality we still have a long way to go,"
Collins said in a telephone interview. "That is mainly because we can't
stop the drugs, people have to take it for a lifetime."
The research was funded by the National Institutes of Health,
Burroughs Wellcome Foundation, University of Michigan, Rackham
Predoctoral Fellowship, National Science Foundation and a Bernard
Maas Fellowship.