Abstract
Upon transmission to a new host, HIV targets CCR5+CD4+ effector memory T cells, resulting in acute, massive depletion of these cells from mucosal effector sites. This depletion does not initially compromise the regenerative capacity of the immune system because naive and most central memory T cells are spared. Here, we discuss evidence suggesting that frequent activation of these spared cells during the chronic phase of HIV infection supplies mucosal tissues with short-lived CCR5+CD4+ effector cells that prevent life-threatening infections. This immune activation also facilitates continued viral replication, but infection and killing of target T cells by HIV are selective and the impact on effector-cell lifespan is limited. We propose, however, that persistent activation progressively disrupts the functional organization of the immune system, reducing its regenerative capacity and facilitating viral evolution that leads to loss of the exquisite target cell–sparing selectivity of viral replication, ultimately resulting in AIDS.
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Acknowledgements
This research was supported, in part, by the Intramural Research Program of the US National Institutes of Health (NIH), National Institute of Allergy and Infectious Diseases. L.J.P. was supported by NIH grant AI054292.
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Grossman, Z., Meier-Schellersheim, M., Paul, W. et al. Pathogenesis of HIV infection: what the virus spares is as important as what it destroys. Nat Med 12, 289–295 (2006). https://doi.org/10.1038/nm1380
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DOI: https://doi.org/10.1038/nm1380