PARIS, Dec 22 (AFP) - A novel treatment, tested on monkeys by a team of Chinese and French scientists, has given a small boost to hopes for dampening the AIDS virus without having to resort to anti-retroviral drugs.
The treatment, based on immature immune-system cells called dendritic cells, led to a roughly hundredfold fall in levels of virus in the blood of 14 rhesus macaques that had been heavily infected with the simian version of the human immunodeficiency virus (HIV).
There was also a sixfold increase in CD4 cells, a key component of the immune arsenal, they report in January's issue of Nature Medicine.
None of the animals had been given anti-retrovirals, the famous "cocktail" of drugs that suppresses levels of the virus but does not eliminate it and often presents toxic side-effects.
"It holds out hope and encourages us to go further," Wei Lu, a Chinese-born French national of the Institute for Research into Vaccines and AIDS and Cancer Immunotherapy in Paris, told AFP.
His team included HIV specialists at the Tropical Medical Institute in Guanghzou, southern China.
The treatment is called a therapeutic vaccine, but these are not vaccines in the classic sense of being a protection against infection. Nor are they a cure.
Rather, they are given to a patient after infection to stimulate an immune response in the aim of stopping the disease from progressing.
It was derived by treating dendritic cells, which are immature immune cells that live in the mucous membranes and capture incoming viruses and bacteria, with an inactivated simian immunodeficiency virus (SIV), the close relative to HIV.
The inactivation was achieved by gently exposing the virus to a chemical, aldrithiol-2, that kept the virus' external envelope intact but destroyed its ability to replicate.
That meant the virus retained the external features that trigger a response by the antibodies, the body's first line of defence, but when it infected the dendritic cells, it could not reproduce.
It marks the first time that anyone has demonstrated that dendritic cells can be used to control HIV in live animals rather than in vitro.
The approach marks a big change from the path usually taken by vaccine designers, which attempts to prime an antibody response or to muster "killer" T-cells, the heavy artillery of the immune system, by exposing them to snippets of the viral coating.
"The striking results of the study are unexpected," say Nina Bharwaj of the New York University and Rockefeller University and Bruce Walker of Harvard Medical School in a commentary.
"It may represent a major new therapeutic approach," they say, adding the caveat that this would need further confirmation in other species of monkeys and eventually in humans.
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