A functional CD8+ cell assay reveals individual variation in CD8+ cell antiviral efficacy and explains differences in human T-lymphotropic virus type 1 proviral load

The CD8+ lymphocyte response is a main component of host immunity, yet it is difficult to quantify its contribution to the control of persistent viruses. Consequently, it remains controversial as to whether CD8+ cells have a biologically significant impact on viral burden and disease progression in infections such as human immunodeficiency virus-1 and human T-lymphotropic virus type I (HTLV-I). Experiments to ascertain the impact of CD8+ cells on viral burden based on CD8+ cell frequency or specificity alone give inconsistent results. Here, an alternative approach was developed that directly quantifies the impact of CD8+ lymphocytes on HTLV-I proviral burden by measuring the rate at which HTLV-I-infected CD4+ cells were cleared by autologous CD8+ cells ex vivo. It was demonstrated that CD8+ cells reduced the lifespan of infected CD4+ cells to 1 day, considerably shorter than the 30 day lifespan of uninfected cells in vivo. Furthermore, it was shown that HTLV-I-infected individuals vary considerably in the rate at which their CD8+ cells clear infected cells, and that this was a significant predictor of their HTLV-I proviral load. Forty to 50 % of between-individual variation in HTLV-I proviral load was explained by variation in the rate at which CD8+ cells cleared infected cells. This novel approach demonstrates that CD8+ cells are a major determinant of HTLV-I proviral load. This assay is applicable to quantifying the CD8+ cell response to other viruses and malignancies and may be of particular importance in assessing vaccines.

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Usefulness of Proviral Load Measurement for Monitoring of Disease Activity in Individual Patients with Human T-Lymphotropic Virus Type I-Associated Myelopathy/Tropical Spastic Paraparesis

Journal of NeuroVirology ◽

10.1080/13550280390173418 ◽

2003 ◽

Vol 9 (1) ◽

pp. 29-35 ◽

Cited By ~ 52

Author(s):

Norihiro Takenouchi ◽

Yoshihisa Yamano ◽

Koichiro Usuku ◽

Mitsuhiro Osame ◽

Shuji Izumo

Keyword(s):

Disease Activity ◽

Virus Type ◽

Proviral Load ◽

Spastic Paraparesis ◽

Tropical Spastic Paraparesis ◽

Type I ◽

T Lymphotropic Virus ◽

Load Measurement

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Accumulation of human T-lymphotropic virus type I (HTLV-I)–infected cells in the cerebrospinal fluid during the exacerbation of HTLV-I–associated myelopathy

Journal of NeuroVirology ◽

10.1080/13550280802178538 ◽

2008 ◽

Vol 14 (5) ◽

pp. 459-463 ◽

Cited By ~ 17

Author(s):

Daisuke Hayashi ◽

Ryuji Kubota ◽

Norihiro Takenouchi ◽

Tomonori Nakamura ◽

Fujio Umehara ◽

...

Keyword(s):

Cerebrospinal Fluid ◽

Virus Type ◽

Type I ◽

T Lymphotropic Virus ◽

Infected Cells

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Inhibition of Human T-Lymphotropic Virus Type I Gene Expression by the Streptomyces-Derived Substance EM2487

Antiviral Chemistry and Chemotherapy ◽

10.1177/095632020201300304 ◽

2002 ◽

Vol 13 (3) ◽

pp. 177-183 ◽

Cited By ~ 5

Author(s):

X Wang ◽

M Okamoto ◽

M Kawamura ◽

S Izumo ◽

M Baba

Keyword(s):

Gene Expression ◽

Virus Type ◽

Mononuclear Cells ◽

Spastic Paraparesis ◽

Selective Inhibition ◽

Pcr Analysis ◽

Type I ◽

Peripheral Blood Mononuclear ◽

T Lymphotropic Virus ◽

Infected Cells

EM2487, a Streptomyces-derived substance, has previously been shown to inhibit HIV-1 replication in both acutely and chronically infected cells. In this study, we found that EM2487 was also a selective inhibitor of human T-lymphotropic virus type I (HTLV-I) replication in persistently infected cells. Its 50% effective concentrations for HTLV-I p19 antigen production were 3.6 and 1.2 μM in MT-2 and MT-4 cells, respectively. However, the compound did not reduce cell proliferation and viability at these concentrations. The 50% cytotoxic concentrations of EM2487 were 30.6 and 5.7 μM in MT-2 and MT-4 cells, respectively. The compound also displayed selective inhibition of HTLV-I production in peripheral blood mononuclear cells obtained from patients with HTLV-I-associated myelopathy/tropical spastic paraparesis. Quantitative reverse transcription PCR analysis revealed that EM2487 selectively suppressed HTLV-I mRNA synthesis in MT-2 cells in a dose-dependent fashion. However, the compound did not inhibit endogenous Tax-induced HTLV-I long terminal repeat-driven reporter gene expression. Furthermore, intracellular Tax accumulation was not suppressed in MT-2 cells exposed to EM2487. These results suggest that the inhibition occurred at the viral transcription level, but it cannot be attributed to the inhibition of the Tax function.

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High proviral load of human T-lymphotropic virus type I in patients with myelodysplastic syndrome carrying HLA-A26

Leukemia & Lymphoma ◽

10.1080/10428190600580858 ◽

2006 ◽

Vol 47 (7) ◽

pp. 1400-1403 ◽

Cited By ~ 2

Author(s):

Kakushi Matsushita ◽

Hirosaka Inoue ◽

Toshimasa Kukita ◽

Kosei Arimura ◽

Atsuo Ozaki ◽

...

Keyword(s):

Myelodysplastic Syndrome ◽

Virus Type ◽

Proviral Load ◽

Type I ◽

T Lymphotropic Virus ◽

High Proviral Load

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Histone deacetylase inhibitors increase virus gene expression but decrease CD8+ cell antiviral function in HTLV-1 infection

Blood ◽

10.1182/blood-2006-03-013235 ◽

2006 ◽

Vol 108 (12) ◽

pp. 3801-3807 ◽

Cited By ~ 27

Author(s):

Angelina Jane Mosley ◽

Kiran N. Meekings ◽

Corinna McCarthy ◽

Dawn Shepherd ◽

Vincenzo Cerundolo ◽

...

Keyword(s):

Gene Expression ◽

Histone Deacetylase ◽

Histone Deacetylase Inhibitors ◽

Ex Vivo ◽

Cytotoxic T Cell ◽

Cell Immune Response ◽

Infected Cells ◽

Cd8 Cell ◽

The Impact

AbstractThe dynamics of human T-lymphotropic virus type-1 (HTLV-1) provirus expression in vivo are unknown. There is much evidence to suggest that HTLV-1 gene expression is restricted: this restricted gene expression may contribute to HTLV-1 persistence by limiting the ability of the HTLV-1–specific CD8+ cell immune response to clear infected cells. In this study, we tested the hypothesis that derepression of HTLV-1 gene expression would allow an increase in CD8+ cell–mediated lysis of HTLV-1–infected cells. Using histone deacetylase enzyme inhibitors (HDIs) to hyperacetylate histones and increase HTLV-1 gene expression, we found that HDIs doubled Tax expression in naturally infected lymphocytes after overnight culture. However, the rate of CD8+ cell–mediated lysis of Tax-expressing cells ex vivo was halved. HDIs appeared to inhibit the CD8+ cell–mediated lytic process itself, indicating a role for the microtubule-associated HDAC6 enzyme. These observations indicate that HDIs may reduce the efficiency of cytotoxic T-cell (CTL) surveillance of HTLV-1 in vivo. The impact of HDIs on HTLV-1 proviral load in vivo cannot be accurately predicted because of the widespread effects of these drugs on cellular processes; we therefore recommend caution in the use of HDIs in nonmalignant cases of HTLV-1 infection.

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Prevention of Mother-to-Child Transmission of Human T-Lymphotropic Virus Type-I

PEDIATRICS ◽

10.1542/peds.86.1.11 ◽

1990 ◽

Vol 86 (1) ◽

pp. 11-17

Author(s):

Yoshiro Tsuji ◽

Hiroshi Doi ◽

Tooru Yamabe ◽

Tadayuki Ishimaru ◽

Tsutomu Miyamoto ◽

...

Keyword(s):

T Cell ◽

Breast Milk ◽

Virus Type ◽

Type I ◽

T Lymphotropic Virus ◽

Adult T Cell Leukemia ◽

Human T Cell ◽

Infected Cells ◽

Mother To Child ◽

Nagasaki Prefecture

Human T-cell lymphotropic virus type I (HTLV-I), an etiologic human retrovirus of adult T-cell leukemia/lymphoma (ATLL), causes approximately 60 new cases of ATLL each year in Nagasaki Prefecture; essentially all cases are fatal, and they account for approximately 0.5% of total deaths in the area. The estimated life risk for an HTLV-I carrier to develop ATLL is approximately 5%. The major transmission pathway of HTLV-I peculiarly endemic in the Nagasaki Prefecture was studied. The prevalence of HTLV-I infection in children of carrier mothers (21%) was significantly higher than that in children in the general population in the area (1%), and more than 85% of mothers of carrier children were carriers. The breast milk of carrier mothers contained HTLV-I-infected cells and was infectious for marmoset via oral administration. A retrospective survey of children of carrier mothers showed that the prevalence of carrier children of carrier mothers was 17 (39%) of 44 and 0 (0%) of 10 when they were given breast milk only or formula only, respectively. These data provide a powerful basis for devising an intervention measure to block the endemic cycle of HTLV-I; ie, if carrier mothers refrain from breast-feeding, the incidence of ATLL will be significantly reduced some 50 years later.

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Pre-morbid human T-lymphotropic virus type I proviral load, rather than percentage of abnormal lymphocytes, is associated with an increased risk of aggressive adult T-cell leukemia/lymphoma

Haematologica ◽

10.3324/haematol.2012.069476 ◽

2012 ◽

Vol 98 (3) ◽

pp. 385-388 ◽

Cited By ~ 12

Author(s):

A. Hodson ◽

D. J. Laydon ◽

B. J. Bain ◽

P. A. Fields ◽

G. P. Taylor

Keyword(s):

T Cell ◽

Virus Type ◽

Proviral Load ◽

Type I ◽

T Cell Leukemia ◽

Cell Leukemia ◽

T Lymphotropic Virus ◽

Adult T Cell Leukemia ◽

Increased Risk

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Transcriptional activation of human TR3/nur77 gene expression by human T-lymphotropic virus type I Tax protein through two AP-1-like elements

Journal of General Virology ◽

10.1099/0022-1317-80-12-3073 ◽

1999 ◽

Vol 80 (12) ◽

pp. 3073-3081 ◽

Cited By ~ 17

Author(s):

Xiangdong Liu ◽

Xiaolin Chen ◽

Vladimir Zachar ◽

Chawnshang Chang ◽

Peter Ebbesen

Keyword(s):

Transcription Factor ◽

Virus Type ◽

Transcriptional Activation ◽

Gene Deletion ◽

Type I ◽

Transcription Start ◽

T Lymphotropic Virus ◽

Tax Protein ◽

Infected Cells ◽

Mutation Analyses

The Tax transactivator of human T-lymphotropic virus type I (HTLV-I) is capable of inducing expression of the human immediate-early TR3/nur77 gene. Deletion and mutation analyses of the TR3/nur77 promoter demonstrated that multiple transcription elements in the 121 bp sequence proximal to the transcription start site are required for full Tax transactivation. Mutations of CArG-like, Ets and RCE motifs in this region severely decreased Tax transactivation. Mutation of either of the two identical AP-1-like elements (NAP 1 and 2) immediately upstream of the TATA box caused around 80% reduction of Tax transactivation. Mutation of both NAP elements blocked Tax-mediated activation totally. These two NAP elements could confer Tax-responsiveness on a heterologous basal promoter. Furthermore, the specific NAP-binding complex was only observed in HTLV-I-infected cells. Formation of this specific NAP-binding complex was correlated directly with Tax expression, as demonstrated in JPX-9 cells upon induction of Tax expression. The specific NAP binding could be competed for by consensus AP-1 and CREB elements, indicating that the NAP-binding proteins probably belong to the AP-1 and CREB/ATF transcription factor families. Supershift analysis with antibodies to both the AP-1 and CREB/ATF transcription factor families revealed that only anti-JunD antibody could partially shift this NAP-binding complex, indicating that JunD is a component of the NAP complex. This work suggests that JunD is involved in Tax-regulated TR3/nur77 expression.

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