A new study has suggested that a sudden loss of T cells (white blood cells that provide continuing immunity to infection) is not the trigger for the progression of AIDS.
A team of researchers at Tulane National Primate Research Center conducted the research that was led by Ivona V. Pandrea and Cristian Apetrei. The study is published in the September 2007 issue of the Journal of Immunology.
The researchers based their suggestion on a study on monkeys by which they found that some non-human primates infected with simian immunodeficiency virus (SIV) do not develop AIDS after sudden, acute loss of T cells - considered to be sufficient to predict progression of last stages of AIDS i.e. the final collapse of the immune system and death.
SIV is a retrovirus that is found, in numerous strains, in primates; the specific strains infecting humans are HIV-1 and HIV-2, the viruses that cause AIDS.
The boffins state that African green monkeys infected with SIV, for example, were found to recover even after a period of severe T cell depletion.
Two companion papers in the Journal of Immunology by researchers from the University of Pennsylvania and Southwestern University of Dallas came to the same conclusions in their studies of sooty mangabeys.
The study raised another question that why monkeys with SIV, unlike HIV-positive humans, are generally resistant to progression to AIDS after infection with the virus.
The answer, the authors propose, is that thousands of years of host/virus co-adaptation has enabled monkeys, the natural hosts of SIV, to effectively limit T cell immune activation and apoptosis, a mechanism that leads to progression of the disease.
By contrast, humans, who were introduced to the virus relatively, recently, have not had the opportunity to develop such protective adaptations.
The researchers also suggested that approaches to control immune system activation and resultant cell death should be considered for use in addition to currently available therapies to slow progression of the disease in HIV-infected individuals.