Efficient Propagation of Human Herpesvirus 6B in a T-Cell Line Derived from a Patient with Adult T-Cell Leukemia/Lymphoma

• Published in: MICROBIOLOGY and IMMUNOLOGY 1999, Vol.43(5), pp.425-436
• Main Authors: Zhou, Chang Fang, Abe, Kenji, Wang, Ping, Ojima, Tomoko, Yamamoto, Kohtaro
• Format: Article
• Language: English
• Subjects: Adult T-cell leukemia/lymphoma; AIDS/HIV; Antigens, CD; Antigens, Differentiation, T-Lymphocyte; Base Sequence; Biological and medical sciences; Cytopathogenic Effect, Viral; DNA Primers; DNA Probes; DNA, Viral - isolation & purification; Enzyme-Linked Immunosorbent Assay; Fundamental and applied biological sciences. Psychology; Genes, pX; Genetic Variation; Herpesvirus 6, Human - genetics; Herpesvirus 6, Human - growth & development; Herpesvirus 6, Human - ultrastructure; Human herpesvirus 6; Human T-lymphotropic virus 1 - genetics; Humans; Leukemia-Lymphoma, Adult T-Cell - pathology; Leukemia-Lymphoma, Adult T-Cell - virology; Microbiology; Molecular Sequence Data; Reverse Transcriptase Polymerase Chain Reaction; T-Lymphocytes - virology; Techniques used in virology; Tumor Cells, Cultured; Variant A; Variant B; Virology; Virus Integration
• ISSN: 0385-5600; 1348-0421
• DOI: 10.1111/j.1348-0421.1999.tb02426.x

The efficient propagation of the OK strain of the B variant of human herpesvirus 6 (HHV-6B) was demonstrated in a line of T cells, TaY, established from the peripheral blood lymphocytes of a patient with adult T-cell leukemia/lymphoma (ATL). Growth of TaY cells depends on the presence of IL-2 and the cells harbor HTLV-I genomes. A severe cytopathic effect (CPE) was observed in many HHV-6B(OK)-infected TaY cells one week after infection. The release of virus from HHV-6B(OK)-infected TaY cells [TaY(OK)] was first detected after three days and increased rapidly for up to seven days after infection, as demonstrated by PCR. The titer of HHV-6B(OK) in the supernatant was comparable to the value of 103.5 TCID50/ml obtained with PHA-activated cord blood lymphocytes (CBL) that had been infected with HHV-6B(OK). The replication of the virus was shown to depend to a considerable extent on cell viability. Electron microscopy revealed many herpesvirus-type capsid- and enveloped-viruses in the nuclei and cytoplasm of degenerated cells in TaY(OK) cultures. The U1102 strain of HHV-6A and the Z29 strain of HHV-6B also infected TaY cells productively, as detected by PCR and an immunofluorescence test. These results suggest that the activation of CD4+ T lymphocytes with mitogens such as PHA or IL-2 and the expression of some cellular gene or the HTLV-I gene might be essential for efficient propagation of HHV-6B. TaY cells should play an important role in future investigations of cell-virus interactions and genetic variations or cell tropism of HHV-6 isolates since no cell line that shows propagation of both HHV-6A and HHV-6B has been reported to date.