High frequencies of functionally competent circulating Tax-specific CD8+ T cells in human T lymphotropic virus type 2 infection

J Immunol. 2009 Sep 1;183(5):2957-65. doi: 10.4049/jimmunol.0900508. Epub 2009 Aug 5.


Human T lymphotropic virus type 2 (HTLV-2) is characterized by a clinically asymptomatic persistent infection in the vast majority of infected individuals. In this study, we have characterized for the first time ex vivo specific CTL responses against the HTLV-2 Tax protein. We could detect CTL responses only against a single HLA-A*0201-restricted Tax2 epitope, comprising residues 11-19 (LLYGYPVYV), among three alleles screened. Virus-specific CTLs could be detected in most evaluated subjects, with frequencies as high as 24% of circulating CD8(+) T cells. The frequency of specific CTLs had a statistically significant positive correlation with proviral load levels. The majority of virus-specific CD8(+) T cells exhibited an effector memory/terminally differentiated phenotype, expressed high levels of cytotoxicity mediators, including perforin and granzyme B, and lysed in vitro target cells pulsed with Tax2((11-19)) synthetic peptide in a dose-dependent manner. Our findings suggest that a strong, effective CTL response may control HTLV-2 viral burden and that this may be a significant factor in maintaining persistent infection and in the prevention of disease in infected individuals.

Publication types

  • Comparative Study

MeSH terms

  • CD8-Positive T-Lymphocytes / immunology*
  • CD8-Positive T-Lymphocytes / metabolism
  • CD8-Positive T-Lymphocytes / virology*
  • Cytotoxicity Tests, Immunologic*
  • Epitope Mapping
  • Epitopes, T-Lymphocyte / blood
  • Epitopes, T-Lymphocyte / immunology*
  • Epitopes, T-Lymphocyte / metabolism
  • Gene Products, tax / blood
  • Gene Products, tax / immunology*
  • Gene Products, tax / metabolism
  • HLA-A Antigens / immunology
  • HLA-A2 Antigen
  • HTLV-II Infections / blood
  • HTLV-II Infections / immunology*
  • HTLV-II Infections / pathology
  • Human T-lymphotropic virus 2 / immunology*
  • Humans
  • Lymphocyte Count*
  • Protein Binding / immunology
  • Proviruses / immunology
  • T-Lymphocytes, Cytotoxic / immunology
  • T-Lymphocytes, Cytotoxic / metabolism
  • T-Lymphocytes, Cytotoxic / virology
  • Viral Load


  • Epitopes, T-Lymphocyte
  • Gene Products, tax
  • HLA-A Antigens
  • HLA-A*02:01 antigen
  • HLA-A2 Antigen
  • tax protein, Human T-lymphotrophic virus 2