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Retrovirology. 2010 Mar 11;7:17. doi: 10.1186/1742-4690-7-17.

Tax gene expression and cell cycling but not cell death are selected during HTLV-1 infection in vivo.

Author information

  • 1CNRS UMR5239, Université de Lyon, Oncovirologie et Biothérapies, Centre Léon Bérard, 69008 Lyon, France.

Abstract

BACKGROUND:

Adult T cell leukemia results from the malignant transformation of a CD4+ lymphoid clone carrying an integrated HTLV-1 provirus that has undergone several oncogenic events over a 30-60 year period of persistent clonal expansion. Both CD4+ and CD8+ lymphocytes are infected in vivo; their expansion relies on CD4+ cell cycling and on the prevention of CD8+ cell death. Cloned infected CD4+ but not CD8+ T cells from patients without malignancy also add up nuclear and mitotic defects typical of genetic instability related to the expression of the virus-encoded oncogene tax. HTLV-1 expression is cancer-prone in vitro, but in vivo numerous selection forces act to maintain T cell homeostasis and are possibly involved in clonal selection.

RESULTS:

Here we demonstrate that the HTLV-1 associated CD4+ preleukemic phenotype and the specific patterns of CD4+ and CD8+ clonal expansion are in vivo selected processes. By comparing the effects of recent (1 month) experimental infections performed in vitro and those observed in cloned T cells from patients infected for >6-26 years, we found that in chronically HTLV-1 infected individuals, HTLV-1 positive clones are selected for tax expression. In vivo, infected CD4+ cells are positively selected for cell cycling whereas infected CD8+ cells and uninfected CD4+ cells are negatively selected for the same processes. In contrast, the known HTLV-1-dependent prevention of CD8+ T cell death pertains to both in vivo and in vitro infected cells.

CONCLUSIONS:

Therefore, virus-cell interactions alone are not sufficient to initiate early leukemogenesis in vivo.

PMID:
20222966
[PubMed - indexed for MEDLINE]
PMCID:
PMC2846874
Free PMC Article
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