title: High frequency of viral protein expression in human T cell lymphotropic virus type 1-infected peripheral blood mononuclear cells.
abstract: Most human T cell lymphotropic virus type (HTLV)-1-infected individuals mount a strong and persistently activated cytotoxic T lymphocyte (CTL) response to the virus, which implies that there is abundant chronic transcription of HTLV-1 genes. On the other hand, several observations suggest that HTLV-1 might be latent in vivo and therefore not detectable by CTLs. To clarify these discrepancies, we quantified the frequency of provirus-positive peripheral blood mononuclear cells (PBMCs) that were capable of expressing the HTLV-1 Tax protein, which is known to be the immunodominant target antigen recognized by HTLV-1-specific CTLs. The analysis showed that a significant proportion of HTLV-1-infected cells (from 14 to 100%) starts to express the Tax protein within a few hours of culture ex vivo. Phenotypic analysis confirmed that the main cell subpopulation expressing the Tax protein is CD4 positive. Frequent Tax expression in CD4(+) T lymphocytes in vivo might account for the chronic activation of the cytotoxic immune response observed in the majority of HTLV-1-infected patients and might contribute to the pathogenesis of HTLV-1-associated diseases.
authors.affiliation: Department of Immunology, Imperial College School of Medicine, St Mary's campus, London W21PG, United Kingdom.
authors.forename: E
authors.initials: E
authors.lastname: Hanon
authors.forename: R E
authors.initials: RE
authors.lastname: Asquith
authors.forename: G P
authors.initials: GP
authors.lastname: Taylor
authors.forename: Y
authors.initials: Y
authors.lastname: Tanaka
authors.forename: J N
authors.initials: JN
authors.lastname: Weber
authors.forename: C R
authors.initials: CR
authors.lastname: Bangham
mesh_terms: D015496:CD4-Positive T-Lymphocytes / Q000276:immunology / Q000821:virology*; D002353:Carrier State / Q000821:virology; D002478:Cells, Cultured; D016356:Gene Products, tax / Q000276:immunology / Q000378:metabolism*; D015368:Human T-lymphotropic virus 1 / Q000378:metabolism*; D006801:Humans; D007963:Leukocytes, Mononuclear / Q000276:immunology / Q000821:virology*; D015493:Paraparesis, Tropical Spastic / Q000276:immunology / Q000821:virology; D010641:Phenotype; D011533:Proviruses / Q000378:metabolism*; D019562:Viral Load
chemical_list: D016356:Gene Products, tax