Cells 'trained to recognise Aids'
2008-05-03 11:17
Washington - A new type of treatment that trains immune system cells to better recognise the Aids virus may help control the deadly and incurable infection, Australian researchers reported on Friday.
Tests on monkeys infected with a similar virus shows the
treatment controlled the infection, although it does not cure
it, and tests are already planned in people.
The treatment is called OPAL, for Overlapping Peptide-pulsed Autologous Cells, and would be categorised as an immunotherapy technique, or a so-called therapeutic vaccine, Stephen Kent of the University of Melbourne and colleagues said.
Writing in the Public Library of Science journal PLoS
Pathogens, they said the treatment involves mixing a patient's
own blood cells with tiny bits of protein from the virus.
These cells are then re-infused into the patient.
"Levels of virus in vaccinated monkeys were 10-fold lower
than in controls, and this was durable for over one year after
the initial vaccinations," they wrote.
Fewer deaths from Aids
"The immunotherapy resulted in fewer deaths from Aids. We
conclude this is a promising immunotherapy technique. Trials in
HIV-infected humans of OPAL therapy are planned."
The Aids virus infects more than 33 million people globally
and has killed 25 million since it was identified in the
1980s.
While there is no cure and no vaccine, cocktails of drugs
can control the virus. But they have side-effects, are
expensive and eventually often stop working.
Kent's team took small bits of the virus called peptides
and placed them in lab dishes with both whole blood and
isolated immune system cells.
This helped train the cells to recognise the virus and
attack it more effectively, they wrote in the paper, freely
available at http://www.plospathogens.org/doi/ppat.1000055.
The macaque monkeys were infected with a related virus
called SIV or simian immunodeficiency virus.
Attacks immune system
HIV is tricky to treat because it attacks the immune
system. It specifically goes after immune cells called CD4 T
cells, the very cells that are supposed to attack and kill
viruses.
"Virus-specific CD4 T cells are typically very weak in
HIV-infected humans or SIV-infected macaques; dramatic
enhancement of these cells were induced by OPAL immunotherapy
and this may underlie its efficacy," they wrote.
The treatment appears to work best if started right after
someone becomes infected.
"Although it may be challenging to identify humans within
three weeks of infection, this is when HIV-1 subjects typically
present (show up at a doctors office) with acute infection,"
they wrote.