Immunopathogenesis of Human T-Cell Leukemia Virus Type-1-Associated Myelopathy/Tropical Spastic Paraparesis: Recent Perspectives

Human T-cell leukemia virus type-1 (HTLV-1) is a replication-competent human retrovirus associated with two distinct types of disease only in a minority of infected individuals: the malignancy known as adult T-cell leukemia (ATL) and a chronic inflammatory central nervous system disease HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP). HAM/TSP is a chronic progressive myelopathy characterized by spastic paraparesis, sphincter dysfunction, and mild sensory disturbance in the lower extremities. Although the factors that cause these different manifestations of HTLV-1 infection are not fully understood, accumulating evidence from host population genetics, viral genetics, DNA expression microarrays, and assays of lymphocyte function suggests that complex virus-host interactions and the host immune response play an important role in the pathogenesis of HAM/TSP. Especially, the efficiency of an individual's cytotoxic T-cell (CTL) response to HTLV-1 limits the HTLV-1 proviral load and the risk of HAM/TSP. This paper focuses on the recent advances in HAM/TSP research with the aim to identify the precise mechanisms of disease, in order to develop effective treatment and prevention.

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Immunogenetics and the Pathological Mechanisms of Human T-Cell Leukemia Virus Type 1- (HTLV-1-)Associated Myelopathy/Tropical Spastic Paraparesis (HAM/TSP)

Interdisciplinary Perspectives on Infectious Diseases ◽

10.1155/2010/478461 ◽

2010 ◽

Vol 2010 ◽

pp. 1-8 ◽

Cited By ~ 16

Author(s):

Mineki Saito

Keyword(s):

T Cell ◽

Virus Type ◽

Leukemia Virus ◽

Spastic Paraparesis ◽

T Cell Leukemia ◽

Cell Leukemia ◽

Cell Leukemia Virus Type ◽

Human T Cell ◽

T Cell Leukemia Virus

Human T-cell leukemia virus type 1 (HTLV-1) is a replication-competent human retrovirus associated with two distinct types of disease only in a minority of infected individuals: the malignancy known as adult T-cell leukemia (ATL) and a chronic inflammatory central nervous system disease HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP). Although the factors that cause these different manifestations of HTLV-1 infection are not fully understood, accumulating evidence suggests that complex virus-host interactions play an important role in determining the risk of HAM/TSP. This review focuses on the role of the immune response in controlling or limiting viral persistence in HAM/TSP patients, and the reason why some HTLV-1-infected people develop HAM/TSP whereas the majority remains asymptomatic carriers of the virus.

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Proviral Features of Human T Cell Leukemia Virus Type 1 in Carriers with Indeterminate Western Blot Analysis Results

Journal of Clinical Microbiology ◽

10.1128/jcm.00659-17 ◽

2017 ◽

Vol 55 (9) ◽

pp. 2838-2849 ◽

Cited By ~ 12

Author(s):

Madoka Kuramitsu ◽

Tsuyoshi Sekizuka ◽

Tadanori Yamochi ◽

Sanaz Firouzi ◽

Tomoo Sato ◽

...

Keyword(s):

T Cell ◽

Virus Type ◽

Proviral Load ◽

Leukemia Virus ◽

T Cell Leukemia ◽

Cell Leukemia ◽

Cell Leukemia Virus Type ◽

Human T Cell ◽

T Cell Leukemia Virus

ABSTRACTWestern blotting (WB) for human T cell leukemia virus type 1 (HTLV-1) is performed to confirm anti-HTLV-1 antibodies detected at the initial screening of blood donors and in pregnant women. However, the frequent occurrence of indeterminate results is a problem with this test. We therefore assessed the cause of indeterminate WB results by analyzing HTLV-1 provirus genomic sequences. A quantitative PCR assay measuring HTLV-1 provirus in WB-indeterminate samples revealed that the median proviral load was approximately 100-fold lower than that of WB-positive samples (0.01 versus 0.71 copy/100 cells). Phylogenic analysis of the complete HTLV-1 genomes of WB-indeterminate samples did not identify any specific phylogenetic groups. When we analyzed the nucleotide changes in 19 HTLV-1 isolates from WB-indeterminate samples, we identified 135 single nucleotide substitutions, composed of four types, G to A (29%), C to T (19%), T to C (19%), and A to G (16%). In the most frequent G-to-A substitution, 64% occurred at GG dinucleotides, indicating that APOBEC3G is responsible for mutagenesis in WB-indeterminate samples. Moreover, interestingly, five WB-indeterminate isolates had nonsense mutations in Pol and/or Tax, Env, p12, and p30. These findings suggest that WB-indeterminate carriers have low production of viral antigens because of a combination of a low proviral load and mutations in the provirus, which may interfere with host recognition of HTLV-1 antigens.

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