Human T cell leukemia virus type I (HTLV-I) molecular genotypes and disease outcome

Molecular modeling studies and comparative analysis on structurally similar HTLV and HIV protease using HIV-PR inhibitors

Retroviruses are most perilous viral family, which cause much damage to the Homo sapiens. HTLV-1 mechanism found to more similar with HIV-1 and both retroviruses are causative agents of severe and fatal diseases including adult T-cell leukemia (ATL) and the acquired immune deficiency syndrome (AIDS). Both viruses code for a protease (PR) that is essential for replication and therefore represents a key target for drugs interfering with viral infection. In this work, the comparative study of HIV-1 and HTLV-1 PR enzymes through sequence and structural analysis is reported along with approved drugs of HIV-PR. Conformation of each HIV PR drugs have been examined with different parameters of interactions and energy scorings parameters. MD simulations with respect to timescale event of 20 ns favors that, few HIV-PR inhibitors can be more active inside the HTLV-1 PR binding pocket. Overall results suggest that, some of HIV inhibitors like Tipranavir, Indinavir, Darunavir and Amprenavir are having good energy levels with HTLV-1. Due to absence of interactions with MET37, here we report that derivatives of these compounds can be much better inhibitors for targeting HTLV-1 proteolytic activity.

Identification of novel defective HCV clones in liver transplant recipients with recurrent HCV infection

Patients with recurrent hepatitis C after liver transplantation usually have a high viral load and are generally resistant to interferon (IFN)-alpha2b plus ribavirin (RBV) therapy. However, it remains unclear whether pretreatment viral titre determines the effectiveness of combination therapy, especially in patients with a high viral load. The aim of this study was to identify the viral factors associated with a sustained virological response (SVR) to antiviral therapy in patients with recurrent hepatitis C after living-donor liver transplantation. Twenty-three patients with recurrent hepatitis C received combination therapy of IFN-alpha2b plus RBV. SVR was achieved in 7 of the 23 patients (30.4%). Predictive factors for SVR included a 2 log10 decline in Hepatitis C virus (HCV) RNA at 2 weeks after the start of therapy and disappearance of HCV RNA at 4 or 24 weeks after the start of therapy. As the pretreatment high viral load showed no association with SVR, we asked whether other viral factor was associated with the response to the combination therapy in transplant recipients. We found the several novel defective HCV clones in 4 of 12 recipients' sera. All defective HCV clones had deletions in the envelope region. Interestingly, no patients with defective clones showed a prompt decrease in HCV RNA after the start of IFN-alpha2b plus RBV therapy. Thus, early decline in serum HCV RNA after treatment was closely associated with SVR. The circulating defective HCV clones are present and might be associated with the response to the combination therapy in patients with recurrent hepatitis after liver transplantation.

Quantitation of HTLV-I proviral load by a TaqMan real-time PCR assay

A quantitative real-time PCR assay was developed to measure the proviral load of human T-lymphotropic virus type I (HTLV-I) in peripheral blood mononuclear cells (PBMCs). The HTLV-I copy number was referred to the actual amount of cellular DNA by means of the quantitation of the albumin gene. Ten copies of HTLV-I DNA could be detected with 100% sensitivity, and the assay had a wide range of at least 5 log(10). Intra- and inter-assay reproducibility was evaluated using independent extractions of PBMCs from an HTLV-I-infected patient (coefficients of variation, 24 and 7% respectively). The performance of this TaqMan PCR assay, coupled with its high throughput, thus allows reliable routine follow-up of HTLV-I proviral load in infected patients. Preliminary results using clinical samples indicate a higher proviral load in patients with HTLV-I-associated myelopathy/tropical spastic paraparesis than in asymptomatic carriers, and also suggest the usefulness of this quantitative measurement to assess the etiological link between HTLV-I and adult T-cell leukaemia/lymphoma-like syndromes.

Human T cell leukemia virus type I and neurologic disease: events in bone marrow, peripheral blood, and central nervous system during normal immune surveillance and neuroinflammation

Human T cell lymphotropic/leukemia virus type I (HTLV-I) has been identified as the causative agent of both adult T cell leukemia (ATL) and HTLV-I-associated myelopathy/tropical spastic paraparesis (HAM/TSP). Although the exact sequence of events that occur during the early stages of infection are not known in detail, the initial route of infection may predetermine, along with host, environmental, and viral factors, the subset of target cells and/or the primary immune response encountered by HTLV-I, and whether an HTLV-I-infected individual will remain asymptomatic, develop ATL, or progress to the neuroinflammatory disease, HAM/TSP. Although a large number of studies have indicated that CD4(+) T cells represent an important target for HTLV-I infection in the peripheral blood (PB), additional evidence has accumulated over the past several years demonstrating that HTLV-I can infect several additional cellular compartments in vivo, including CD8(+) T lymphocytes, PB monocytes, dendritic cells, B lymphocytes, and resident central nervous system (CNS) astrocytes. More importantly, extensive latent viral infection of the bone marrow, including cells likely to be hematopoietic progenitor cells, has been observed in individuals with HAM/TSP as well as some asymptomatic carriers, but to a much lesser extent in individuals with ATL. Furthermore, HTLV-I(+) CD34(+) hematopoietic progenitor cells can maintain the intact proviral genome and initiate viral gene expression during the differentiation process. Introduction of HTLV-I-infected bone marrow progenitor cells into the PB, followed by genomic activation and low level viral gene expression may lead to an increase in proviral DNA load in the PB, resulting in a progressive state of immune dysregulation including the generation of a detrimental cytotoxic Tax-specific CD8(+) T cell population, anti-HTLV-I antibodies, and neurotoxic cytokines involved in disruption of myelin-producing cells and neuronal degradation characteristic of HAM/TSP.

Human T-cell lymphotropic-I-associated leukemia/lymphoma

Human T-cell lymphotropic virus-I (HTLV-I)-related adult T-cell leukemia/lymphoma (ATL) is a model disease for proof of viral oncogenesis. HTLV-I infection is endemic in southern Japan and the Caribbean basin, and occurs sporadically in Africa, Central and South America, the Middle East, and the southeastern United States. ATL occurs in only 2% to 4% of HTLV-I-infected people [1-3]. When it does occur, it is usually aggressive and difficult to treat; most people survive for less than 1 year [1-3]. Combination chemotherapy with cytotoxic agents has yielded complete response rates of 20% to 45%, but responses usually last only a few months [3]. Recently, novel treatments, such as monoclonal antibodies directed at the interleukin-2 receptor and the combination of interferon alfa and zidovudine, have been shown to be active in the treatment of patients with ATL. A small percentage of patients achieve long-lasting remissions [2,3].

Smoldering HTLV-1-induced T-cell lymphoma localized within the skin; a radiation-resistant tumor

BACKGROUND

Human T-cell lymphotrophic virus type 1 (HTLV-1)-induced lymphoproliferative disease occurs in approximately 3-5% of people in endemic areas who have been HTLV-1 positive for decades. Lymphoproliferative disease may present as four subtypes, including an acute adult T-cell leukemia/lymphoma (ATLL), an aggressive HTLV-1 lymphoma, chronic ATLL, and smoldering ATLL.

MATERIALS AND METHODS

A 72-year-old HTLV-1+ Haitian woman presented with a 2-year history of a cutaneous eruption localized to the right arm. The eruption had evolved into multinodular lesions over the past 6-7 months. Peripheral blood and cutaneous biopsy specimens were evaluated. Immunohistochemical studies for lymphoid markers were performed on the cutaneous biopsy material, and polymerase chain reaction (PCR) and Southern blot assay were evaluated for the presence and integration of HTLV-1 within the genome.

RESULTS

The biopsy specimen showed a pleomorphic T-cell infiltrate with epidermotrophism, and an immunohistochemical phenotype showing CD3+, CD4+, CD8-, CD25, CD30-, HLDA-DR+ cells. PCR and Southern blot assay evaluation showed a single clonal integration of HTLV-1 provirus within a monoclonal tumor cell population. The patient had no abnormal lymphoid forms on peripheral smear at presentation, and no evidence of other organ involvement.

CONCLUSIONS

Smoldering HTLV-1-induced lymphoma is uncommon even in endemic areas. In previously reported cases, the smoldering variant was accompanied by abnormal forms in the peripheral blood and/or by other signs of systemic disease. This case illustrates that smoldering disease may be localized to the skin with no detected morphologic abnormalities on peripheral smear.

Passage of human T-cell leukemia virus type-1 during progression to cutaneous T-cell lymphoma results in myelopathic disease in an HTLV-1 infection model

Studies comparing functional differences in human T-cell leukemia virus type 1 (HTLV-1) clones that mediate distinct outcomes in experimentally infected rabbits, resulted in a dermatopathic smoldering adult T-cell leukemia/lymphoma following chronic infection with HTLV-1 strain RH/K34. During the 3.5 years' follow-up, HTLV-1 skin disease progressed to cutaneous T-cell lymphoma. When infection was passed to several naive rabbits, progressive paraparesis due to myelopathic neurodegeneration, analogous to HTLV-associated myelopathy, resulted in one of 4 transfusion recipients. Similar proviral loads were detected in the two diseases, regardless of stage of progression or tissue compartment of infection. Complete proviral sequences obtained from the donor and affected recipient aligned identically with each other and with the inoculated virus clone. Existence of disparate pathogenic outcomes following infectious transmission further extends the analogy of using rabbits to model human infection and disease. Although the experimental outcomes shown are limited by numbers of animals affected, they mimic the infrequency of HTLV-1 disease and authenticate epidemiological evidence of virus sequence stability regardless of disease phenotype. The findings suggest that further investigation of a possible role for HTLV-1 in some forms of cutaneous T-cell lymphoma is warranted.

Peripherally inserted central catheters in patients with AIDS are associated with a low infection rate

We reviewed the medical records of all human immunodeficiency virus (HIV)-infected patients who had a peripherally inserted central catheter (PICC) placed during a 1-year period. Ninety-seven PICCs were inserted in 66 patients for 8337 catheter-days. Eighty of 97 catheters were used primarily to treat cytomegalovirus disease. The mean time to any complication was 150 days. The total complication rate was 6.1 per 1000 catheter-days. The total infection rate was 1. 3 per 1000 catheter-days, and the serious infection rate was 0.8 per 1000 catheter-days. The mean time to a serious infection was 310 days. The noninfectious complication rate was 4.6 per 1000 catheter-days. PICCs were associated with a low infection rate and a moderate mechanical complication rate, which compare favorably with historical rates seen in AIDS patients with other types of central venous access devices. PICCs are a reasonable alternative to other central venous access devices in patients with HIV or AIDS.

Quantification of human T-cell lymphotropic virus type 1 proviral load by quantitative competitive polymerase chain reaction

The polymerase chain reaction (PCR) has been established as a highly sensitive technique for detection of viral DNA or RNA. However, due to inherent limitations of PCR the amount of amplified product often does not correlate with the initial amount of template DNA. This is particularly true for PCR detection of viral infections that are characterized by low in vivo viral copy numbers in certain stages of the infection, such as human T-cell lymphotropic virus type 1 (HTLV-1) and simian T-cell lymphotropic virus type 1 (STLV-1). Therefore, we developed a quantitative competitive polymerase chain reaction (qcPCR) for detection of HTLV-1 and STLV-1 proviral DNA. The assay was optimized using an infectious HTLV-1 clone, ACH, HTLV-1 infected cell lines, MT-2.6 and HUT-102 and STLV-1 infected lines Kia and Matsu. Applicability of this system was demonstrated by determining HTLV-1 proviral load in peripheral blood mononuclear cells (PBMC) of human subjects with HTLV-1 associated diseases and an asymptomatic carrier as well as rabbits infected experimentally. This qcPCR method, the first designed specifically for HTLV-1 and STLV-1, will provide an important tool for pathogenesis studies of HTLV-1 and for evaluating the efficacy of antiviral drugs and vaccines against the viral infection using animal models.