title: In vitro cellular tropism of human T cell leukemia virus type 2.
abstract: Human T cell leukemia virus type 1 (HTLV-1) and 2 (HTLV-2) are distinct oncogenic retroviruses that infect several cell types, but display their biologic/pathogenic activity only in T lymphocytes. HTLV-1 is associated with adult T cell leukemia, a malignancy of mature CD4(+) T cells, and a chronic neurological disorder termed HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP). HTLV-2 is less pathogenic and has been associated with a few cases of a variant of hairy cell leukemia and neurological disease. Previous studies have indicated that in vivo HTLV-1 has a preferential tropism for CD4(+) T cells, whereas HTLV-2 in vivo tropism is less clear, but appears to favor CD8(+) T cells. The molecular mechanism that determines the cellular tropism of HTLV-1 and HTLV-2 has not been precisely determined. However, one study by our group has provided evidence that HTLV-1-enhanced viral transcription in CD4(+) T cells may be responsible for its tropism. In an effort to understand HTLV-2 tropism we tested the ability of HTLV-2 to infect, replicate in, and transform purified CD4(+) or CD8(+) T cells in cell culture. After cocultures of purified primary human CD4(+) and CD8(+) T cells with an HTLV-2-producer cell line we measured viral transcription by reverse transcription PCR analysis, virus production by p19(gag) ELISA, proviral integration by DNA slot-blot analysis, surface phenotype by FACS analysis, and cellular transformation. We also measured HTLV-2 long terminal repeat-directed transcription in the presence and absence of Tax in purified CD4(+) and CD8(+) T cells, using transient transfection assays. Our data indicate that CD4(+) and CD8(+) T cells are equally susceptible to HTLV-2 infection. We observed no significant difference in viral transcription based on mRNA and virus production in CD4(+) and CD8(+) T cell cocultures. Although LTR transcription was enhanced 12- to 16-fold in the presence of Tax, there was no significant difference in CD4(+) or CD8(+) T cells. Interestingly, we show that HTLV-2 preferentially transforms CD8(+) T cells in culture. Together, our data indicate that, unlike HTLV-1, HTLV-2 cell tropism is not due to inhibition of viral infection and inefficient gene expression in CD4(+) versus CD8(+) T cells, and likely involves unique interactions with viral and CD8(+) T cell-specific proteins.
authors.affiliation: Center for Retrovirus Research and Department of Veterinary Biosciences, Ohio State University, Columbus, Ohio 43210, USA.
authors.forename: T G
authors.initials: TG
authors.lastname: Wang
authors.forename: J
authors.initials: J
authors.lastname: Ye
authors.forename: M D
authors.initials: MD
authors.lastname: Lairmore
authors.forename: P L
authors.initials: PL
authors.lastname: Green
mesh_terms: D015496:CD4-Positive T-Lymphocytes / Q000821:virology*; D018414:CD8-Positive T-Lymphocytes / Q000821:virology*; D002472:Cell Transformation, Viral; D002478:Cells, Cultured; D018920:Coculture Techniques; D015367:Human T-lymphotropic virus 2 / Q000235:genetics / Q000472:pathogenicity* / Q000502:physiology; D006801:Humans; D008156:Luciferases / Q000235:genetics / Q000378:metabolism; D012367:RNA, Viral / Q000378:metabolism; D020079:Terminal Repeat Sequences / Q000235:genetics; D014162:Transfection; D014779:Virus Replication
chemical_list: D012367:RNA, Viral; D008156:Luciferases