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Science  12 Mar 2004:
Vol. 303, Issue 5664, pp. 1585
DOI: 10.1126/science.303.5664.1585b

Substantial progress has been made in the treatment of HIV infection using highly active antiretroviral therapy (HAART). Nevertheless, a serious limitation of this form of treatment is its inability to eliminate latent infection, meaning that patients must remain on HAART indefinitely to maintain low levels of the virus. Multiple approaches aimed at depleting the latent HIV reservoir have not, so far, met with success.

Saavedra-Lozano et al. employed an immunotoxin (IT) to target memory CD45RO+ CD4+ T cells, which make up a dominant fraction of the latent HIV reservoir. In previous work, the authors demonstrated that CD45RO-IT depletes virally infected T cells in vitro, although it was not clear whether similar effects would be seen on T cells from latently infected patients with very low viremia. In the new study, a significant decline in CD4+ T cell-associated virus was observed after ex vivo CD45RO-IT treatment of peripheral blood mononuclear cells from HAART patients whose viral titers were below levels that could be quantified. Encouragingly, the treatment had only marginal impact on CD8+ T cell memory responses, suggesting that IT-based therapy might be effective at eliminating the latent HIV reservoir while preserving a significant fraction of remaining memory T cells. — SJS

Proc. Natl. Acad. Sci. U.S.A. 101, 2494 (2004).

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