The immune control of HTLV-1 infection: selection forces and dynamics

Front Biosci (Landmark Ed). 2009 Jan 1;14:2889-903. doi: 10.2741/3420.


Cytotoxic T lymphocytes (CTLs) play a central role in the protective immune response to human T-lymphotropic virus 1 (HTLV-1). Here we consider two questions. First, what determines the strength of an individual's HTLV-1-specific CTL response? Second, what controls the rate of expression of HTLV-1 in vivo, which is greater in patients with HAM/TSP than in asymptomatic carriers with the same proviral load? Recent evidence shows that FoxP3+CD4+ T cells are abnormally frequent in HTLV-1 infection, and the frequency of these cells is inversely correlated with the rate of CTL lysis of HTLV-1-infected cells, suggesting that FoxP3+CD4+ cell frequency is an important determinant of the outcome of HTLV-1 infection. There is also new evidence that the rate of expression of HTLV-1 in vivo is associated with the transcriptional activity of the flanking host genome. We suggest that the frequencies of HTLV-1-infected T cell clones in vivo are determined by a dynamic balance between positive and negative selection forces that differ among the clones.

Publication types

  • Research Support, Non-U.S. Gov't
  • Review

MeSH terms

  • Genome, Viral
  • Genotype
  • HTLV-I Infections / immunology*
  • HTLV-I Infections / virology
  • Human T-lymphotropic virus 1 / genetics
  • Humans
  • Paraparesis, Tropical Spastic / virology
  • T-Lymphocytes, Cytotoxic / immunology
  • Viral Load