The virus of Japanese adult T-cell leukaemia is a member of the human T-cell leukaemia virus group

Safety of intraocular anti-VEGF antibody treatment under in vitro HTLV-1 infection

Introduction

HTLV-1 (human T-cell lymphotropic virus type 1) is a retrovirus that infects approximately 20 million people worldwide. Many diseases are caused by this virus, including HTLV-1-associated myelopathy, adult T-cell leukemia, and HTLV-1 uveitis. Intraocular anti-vascular endothelial growth factor (VEGF) antibody injection has been widely used in ophthalmology, and it is reportedly effective against age-related macular degeneration, complications of diabetic retinopathy, and retinal vein occlusions. HTLV-1 mimics VEGF₁₆₅, the predominant isoform of VEGF, to recruit neuropilin-1 and heparan sulfate proteoglycans. VEGF₁₆₅ is also a selective competitor of HTLV-1 entry. Here, we investigated the effects of an anti-VEGF antibody on ocular status under conditions of HTLV-1 infection in vitro.

Methods

We used MT2 and TL-Om1 cells as HTLV-1-infected cells and Jurkat cells as controls. Primary human retinal pigment epithelial cells (HRPEpiCs) and ARPE19 HRPEpiCs were used as ocular cells; MT2/TL-Om1/Jurkat cells and HRPEpiCs/ARPE19 cells were co-cultured to simulate the intraocular environment of HTLV-1-infected patients. Aflibercept was administered as an anti-VEGF antibody. To avoid possible T-cell adhesion, we lethally irradiated MT2/TL-Om1/Jurkat cells prior to the experiments.

Results

Anti-VEGF antibody treatment had no effect on activated NF-κB production, inflammatory cytokines, chemokines, HTLV-1 proviral load (PVL), or cell counts in the retinal pigment epithelium (RPE) under MT2 co-culture conditions. Under TL-Om1 co-culture conditions, anti-VEGF antibody treatment did not affect the production of activated NF-κB, chemokines, PVL, or cell counts, but production of the inflammatory cytokine IL-6 was increased. In addition, anti-VEGF treatment did not affect PVL in HTLV-1-infected T cells.

Conclusion

This preliminary in vitro assessment indicates that intraocular anti-VEGF antibody treatment for HTLV-1 infection does not exacerbate HTLV-1-related inflammation and thus may be safe for use.

Tuning Rex rules HTLV-1 pathogenesis

HTLV-1 is an oncovirus causing ATL and other inflammatory diseases such as HAM/TSP and HU in about 5% of infected individuals. It is also known that HTLV-1-infected cells maintain a disease-free, immortalized, latent state throughout the lifetimes of about 95% of infected individuals. We believe that the stable maintenance of disease-free infected cells in the carrier is an intrinsic characteristic of HTLV-1 that has been acquired during its evolution in the human life cycle. We speculate that the pathogenesis of the virus is ruled by the orchestrated functions of viral proteins. In particular, the regulation of Rex, the conductor of viral replication rate, is expected to be closely related to the viral program in the early active viral replication followed by the stable latency in HTLV-1 infected T cells. HTLV-1 and HIV-1 belong to the family Retroviridae and share the same tropism, e.g., human CD4⁺ T cells. These viruses show significant similarities in the viral genomic structure and the molecular mechanism of the replication cycle. However, HTLV-1 and HIV-1 infected T cells show different phenotypes, especially in the level of virion production. We speculate that how the activity of HTLV-1 Rex and its counterpart HIV-1 Rev are regulated may be closely related to the properties of respective infected T cells. In this review, we compare various pathological aspects of HTLV-1 and HIV-1. In particular, we investigated the presence or absence of a virally encoded “regulatory valve” for HTLV-1 Rex or HIV-1 Rev to explore its importance in the regulation of viral particle production in infected T cells. Finally, wereaffirm Rex as the key conductor for viral replication and viral pathogenesis based on our recent study on the novel functional aspects of Rex. Since the activity of Rex is closely related to the viral replication rate, we hypothesize that the “regulatory valve” on the Rex activity may have been selectively evolved to achieve the “scenario” with early viral particle production and the subsequent long, stable deep latency in HTLV-1 infected cells.

Reflections on Some of the Exceptional Features of HTLV-1 and HTLV-1 Research: A Perspective

The report is not a review or a summary. In a manner, it is a perspective but an unusual one. It looks back to the years my colleagues and I (RG) began preparing for human retroviruses (beginning in 1970), how they evolved, and attempts to bring to light or simply to emphasize many exceptional characteristics of a retrovirus known as HTLV-1 and some fortuitous coincidences, with emphasis on the needs of the field. These events cover over one half a century. We have had many reviews on HTLV-1 disease, epidemiology, and basic aspects of its replication, genome, gene functions, structure, and pathogenesis, though continued updates are needed. However, some of its truly exceptional features have not been highlighted, or at least not in a comprehensive manner. This article attempts to do so.

Tocilizumab has no direct effect on cell lines infected with human T-cell leukemia virus type 1

Objective

It remains unclear whether human T-cell leukemia virus type 1 (HTLV-1) infection influences therapeutic responses in patients with rheumatic diseases and whether immunosuppressive treatments increase the risk of HTLV-1-related complications in HTLV-1 carriers with rheumatic diseases. We examined the effects of tocilizumab (TCZ), an interleukin (IL)-6 receptor antagonist, on two HTLV-1-infected T-cell lines (HCT-5 and MT-2) in vitro.

Methods

We evaluated production of cytokines and chemokines, expression of HTLV-I associated genes, HTLV-1 proviral load (PVL), expression of HTLV-1 structural proteins, and apoptosis.

Results

There were no significant differences in cytokine and chemokine levels in the culture supernatants of HCT-5 and MT-2 cells treated with phosphate-buffered saline (PBS) or TCZ. No significant differences were detected in mRNA abundance of Tax or HBZ, PVL, expression of the HTLV-1 structural protein GAG, or apoptosis among HCT-5 and MT-2 cells treated with PBS or TCZ.

Conclusions

TCZ had no effect the cytokine profiles, HTLV-1 gene and protein expression, PVL, or apoptosis in HTLV-1-infected T-cell lines. Thus, TCZ treatment has no effect on HTLV-1 infection in vitro.

Provirus Mutations of Human T-Lymphotropic Virus 1 and 2 (HTLV-1 and HTLV-2) in HIV-1-Coinfected Individuals

Provirus mutations of human T-lymphotropic virus 1 (HTLV-1), mostly the lack of the 5' long terminal repeat (LTR) genomic region, have been described and associated with severe adult T cell leukemia/lymphoma (ATLL), non-sense point mutations with low proviral load, and Western blotting indeterminate results. Until now, no information concerning provirus mutations of HTLV-2 and its consequences, as well as those of HTLV-1/2 in HIV-coinfected individuals, had been described. Therefore, we searched for these mutations in provirus samples of 44 HIV/HTLV-1- and 25 HIV/HTLV-2-coinfected individuals. Using protocols well established for amplification and sequencing of segments of the LTR, env, and tax regions, we searched for defective type 1 particles that retain LTRs and lack internal sequences and type 2 particles that lack the 5'LTR region. In addition, using as references the prototypes ATK (HTLV-1) and Mo (HTLV-2), we searched for point mutations in the LTR and synonyms and nonsynonymous mutations and non-sense mutations in env and tax regions. Defective HTLV-1 and HTLV-2 provirus type 1 or 2 was detected in 31.8% of HIV/HTLV-1- and 32.0% of HIV/HTLV-2-coinfected individuals. Synonymous and nonsynonymous mutations were identified mostly in HTLV-2 and associated with lower levels of specific antibodies. No non-sense mutations that resulted in premature termination of Env and Tax proteins were detected. On the contrary, mutation in the stop codon of Tax2a produced a long protein characteristic of the HTLV-2c subtype. The clinical significance of these mutations in coinfected individuals remains to be defined, but they confirmed the lower sensitivity of serological and molecular diagnostic tests in HIV/HTLV-1/2 coinfections.IMPORTANCE HTLV-1 and HTLV-2 are endemic to Brazil, and they have different effects in HIV/AIDS disease progression. HIV/HTLV-1 has been described as accelerating the progression to AIDS and death, while HIV/HTLV-2 slows the progression to AIDS. Provirus mutations of HTLV-1 were implicated in severe leukemia development and in problems in the diagnosis of HTLV-1; in contrast, provirus mutations of HTLV-2 had not been confirmed and associated with problems in HTLV-2 diagnosis or disease outcome. Nevertheless, data obtained here allowed us to recognize and understand the false-negative results in serologic and molecular tests applied for HTLV-1 and HTLV-2 diagnosis. Defective proviruses, as well as synonymous and nonsynonymous mutations, were associated with the diagnosis deficiencies. Additionally, since HIV-1 and HTLV-1 infect the same cells (CD4 positive), the production of HIV-1 pseudotypes with HTLV-1 envelope glycoprotein during HIV/HTLV-1 coinfection cannot be excluded. Defective provirus of HTLV-2 and Tax2c is speculated to influence progression to AIDS.

Treatment with mogamulizumab or lenalidomide for relapsed adult T-cell leukemia/lymphoma after allogeneic hematopoietic stem cell transplantation: The Nagasaki transplant group experience

Mogamulizumab (Mog) and lenalidomide (Len) are new therapeutic candidates for relapsed adult T-cell leukemia/lymphoma after allogeneic hematopoietic stem cell transplantation (allo-HSCT). In the present study, we retrospectively analyzed 12 patients who received Mog or Len monotherapy for relapsed ATL after allo-HSCT. Eight and three patients received Mog and Len, respectively. The remaining patient received Mog for the first relapse and Len for the third relapse. A complete response was achieved by three and two patients who received Mog and Len, respectively, two and one of whom remained alive with a complete response for more than 20 months. In terms of adverse events, the emergence or progression of graft-versus-host disease was observed in three out of four patients treated with Len and in none of the patients treated with Mog. The development or progression of cytomegalovirus reactivation was detected in four out of eight patients treated with Mog and in none of those treated with Len. The present results suggest that Mog and Len would be promising treatment options for relapsed ATL after allo-HSCT and need to be selected based on adverse event profiles.

40 years of the human T-cell leukemia virus: past, present, and future

It has been nearly 40 years since human T-cell leukemia virus-1 (HTLV-1), the first oncogenic retrovirus in humans and the first demonstrable cause of cancer by an infectious agent, was discovered. Studies indicate that HTLV-1 is arguably one of the most carcinogenic agents to humans. In addition, HTLV-1 causes a diverse array of diseases, including myelopathy and immunodeficiency, which cause morbidity and mortality to many people in the world, including the indigenous population in Australia, a fact that was emphasized only recently. HTLV-1 can be transmitted by infected lymphocytes, from mother to child via breast feeding, by sex, by blood transfusion, and by organ transplant. Therefore, the prevention of HTLV-1 infection is possible but such action has been taken in only a limited part of the world. However, until now it has not been listed by the World Health Organization as a sexually transmitted organism nor, oddly, recognized as an oncogenic virus by the recent list of the National Cancer Institute/National Institutes of Health. Such underestimation of HTLV-1 by health agencies has led to a remarkable lack of funding supporting research and development of treatments and vaccines, causing HTLV-1 to remain a global threat. Nonetheless, there are emerging novel therapeutic and prevention strategies which will help people who have diseases caused by HTLV-1. In this review, we present a brief historic overview of the key events in HTLV-1 research, including its pivotal role in generating ideas of a retrovirus cause of AIDS and in several essential technologies applicable to the discovery of HIV and the unraveling of its genes and their function. This is followed by the status of HTLV-1 research and the preventive and therapeutic developments of today. We also discuss pending issues and remaining challenges to enable the eradication of HTLV-1 in the future.

Association between serum zinc and copper levels and antioxidant defense in subjects infected with human T-lymphotropic virus type 1

Introduction

Copper (Cu) and zinc (Zn) are important trace elements that are also structural ions of superoxide dismutase (SOD), which reduce oxidative stress. Zinc deficiency and excess copper have been reported to be associated with inflammation. The human T-lymphotropic virus type 1 (HTLV-1) is a retrovirus, which is believed to cause systemic inflammation. The aim of this study is to measure levels of Zn, Cu, SOD, and prooxidant–antioxidant balance (PAB) in HTLV-1-positive patients and investigate the association between serum Zn and Cu concentrations and levels of oxidative stress in them.

Methods

The serum samples of 1,116 subjects who had participated in the “Mashhad Stroke and Heart Atherosclerotic Disorder” study, including 279 HTLV-1-positive and 837 HTLV-1-negative patients, were used. Levels of Zn, Cu, SOD, and PAB were measured.

Results

Zinc and SOD levels were lower in the HTLV-1-positive group; however, the difference was statistically significant only for the level of SOD (P=0.003). On the other hand, levels of copper and PAB were significantly higher in HTLV-1 positive subjects; P=0.004 and P=0.002, respectively.

Conclusion

In HTLV-infected patients, serum Zn concentration is lower and Cu concentration is higher than healthy controls. This altered situation might be either primary or secondary to HTLV-1 infection, which should be investigated in larger studies. We showed that SOD is significantly lower in HTLV-1-infected subjects. As in some other viruses that evolve different mechanisms to potentiate virus replication by changing the physiologic condition of host cells, HTLV-1 too probably decreases the activity of copper–zinc SOD1 by suppressing its gene.

Morphological alterations in minor salivary glands of HTLV1+ patients: A pilot study

BACKGROUND

Among the complex of HTLV-associated diseases, Sjögren's syndrome (SS) is one of the most controversial. This work aims to detect morphological and inflammatory alterations, including clues of the presence of HTLV-1, in minor salivary glands of patients with dryness symptoms.

METHODS

We have assessed HTLV-1-seropositive patients (HTLV-1 group) and patients with SS (SS group). We used formalin-fixed, paraffin-embedded minor salivary gland tissue to evaluate the morphological aspects and, by means of immunohistochemistry, the presence of Tax protein, CD4, CD8 and CD20 cells. Additionally, viral particles and proviral load were analysed by PCR.

RESULTS

The HTLV-1 group had the highest prevalence of non-specific chronic sialadenitis (85.71%; P = 0.017) and greater amount of T CD8⁺ cells. In the SS group, focal lymphocytic sialadenitis (80%; P = 0.017) prevailed, with a greater amount of B CD20⁺ . Both immunohistochemistry and PCR identified the Tax protein and its gene in the salivary glands of both groups and in similar proportions.

CONCLUSION

The results indicate that HTLV-1-seropositive patients have different patterns of morphological/inflammatory alterations, suggesting a likely difference in the process of immune activation.

Searching for human oncoviruses: Histories, challenges, and opportunities

Oncoviruses contribute significantly to cancer burden. A century of tumor virological studies have led to the discovery of seven well-accepted human oncoviruses, cumulatively responsible for approximately 15% of human cancer cases. Virus-caused cancers are largely preventable through vaccination. Identifying additional oncoviruses and virus-caused tumors will advance cancer prevention and precision medicine, benefiting affected individuals, and society as a whole. The historic success of finding human oncoviruses has provided a unique lesson for directing new research efforts in the post-sequencing era. Combing the experiences from these pioneer studies with emerging high-throughput techniques will certainly accelerate new discovery and advance our knowledge of the remaining human oncoviruses.

Tumor necrosis factor alpha inhibitors have no effect on a human T-lymphotropic virus type-I (HTLV-I)-infected cell line from patients with HTLV-I-associated myelopathy

Background

While tumor necrosis factor alpha (TNF-α) inhibitors (TNFi) and other biologics are very effective against autoimmune diseases, they can also cause infectious diseases. Therefore, it is important to clarify whether the TNFi sometimes used to treat patients with rheumatoid arthritis (RA) complicated with human T-lymphotropic virus type-I (HTLV-I) infection have the unintended side effect of promoting HTLV-I proliferation.

Methods

We used the HTLV-I-infected cell line HCT-5, derived from spinal fluid cells of a patient with HTLV-I associated myelopathy, to evaluate the production of cytokines and chemokines, TNF-α receptor (TNFR), the expression of HTLV-I associated genes, the HTLV-I proviral load (PVL), the expression of HTLV-I structural protein, and apoptosis. We used Jurkat cells as a control.

Results

Supernatants of HCT-5 showed time-dependent elevations of IL-6, RANTES and ICAM-1. HCT-5 supernatants treated with infliximab, adalimumab, etanercept (ETN), golimumab and certolizumab pegol showed no significant differences in the levels of these molecules compared to the control. Neither TNFR1 nor TNFR2 expression was altered by any TNFi treatment, relative to phosphate-buffered saline (PBS) treatment, with the exception that TNFR2 was significantly decreased and internalized in HCT-5 cells by ETN treatment. The HTLV-I associated genes Tax and HBZ and the PVL levels were not significantly changed. Immunofluorescence staining of HCT-5 for an HTLV-I-associated protein, GAG, was also not significantly different between any of the TNFi treatments and the PBS treatment. DNA ladders as an index of apoptosis were not detected. Apoptotic cells were not increased by the addition of any TNFi.

Conclusions

In vitro, TNFi did not affect the cytokine profiles, expression of associated genes and proteins, proviral load or apoptosis of HCT-5 cells. The results suggested that TNFi treatment of RA patients complicated with HTLV-I might have no effect on HTLV-I infection.

Prevalence of Sjögren's syndrome in Brazilian patients infected with human T-cell lymphotropic virus

BACKGROUND

Human T-lymphotropic virus type I (HTLV-I) is known to be associated with neoplastic and neurodegenerative changes, and it is believed to be associated with various systemic inflammatory diseases, including Sjögren's syndrome (SS). Although HTLV-I infection is endemic in Brazil, there is no information regarding the association between HTLV-I infection and SS in the Brazilian population. The objective of this study was to determine the prevalence of SS in HTLV-I-infected individuals and the prevalence of HTLV-I infection in individuals diagnosed with SS.

METHODS

Serology for HTLV-I was performed in 50 patients presenting with complaints consistent with SS (the SS group). The HTLV-I group comprised 129 HTLV-I-infected patients who were screened for SS.

RESULTS

None of the patients in the SS group tested positive for HTLV-I. Of the 129 patients in the HTLV-I group, 46 (35.7%) had xerostomia, 18 (13.95%) had xerophthalmia, eight (6.2%) had hyposalivation, two (1.55%) showed impaired tear secretion, and one (0.77%) was positive for autoantibodies (anti-SSB). In addition, six underwent minor salivary gland biopsy, and the histopathological findings were consistent with SS. Only two (1.55%) met the diagnostic criteria for SS.

CONCLUSIONS

The prevalence of SS was found to be three times as high in HTLV-I-infected individuals as it was in those without HTLV-I infection. However, given the small number of HTLV-seropositive patients with SS, it is impossible to state that HTLV acts as an immune-activating pathogen for SS.

Human T-cell Lymphotropic Viruses: Review and Prospects for Antiviral Therapy

The human T-cell lymphotropic viruses types I and II (HTLV-I, II) pose challenges to researchers and clinicians who seek to unveil mechanisms of viral transformation and pathogenesis. HTLV-I infection in humans is associated with a wide array of primary and secondary diseases ranging from mild immunosuppression to adult T-cell leukaemia/lymphoma and HTLV-associated myelopathy/tropical spastic paraparesis (HAM/TSP), a neurological degenerative syndrome. As retroviruses, HTLV-I and II share similar replicative cycles with human immunodeficiency virus (HIV), the causative agent of acquired immunodeficiency syndrome. However, in contrast to HIV-I which destroys CD4+ T cells, HTLV-I and II can preferentially transform a CD4+ T-cell subset to an unrestricted growth state.

HTLV-I and II, along with simian T-lymphotropic virus (STLV) and bovine leukaemia virus (BLV), form a phylogenetic group which is distinct from ungulate, non-human primate and human lentiviruses such as visna, simian immunodeficiency virus (SIV), and human immunodeficiency viruses types 1 and 2. The proviral genome of HTLV-I is flanked at the 5′ and 3′ ends by long terminal repeats (LTR) and is further subdivided into structural gag and env genes, a pro gene encoding an aspartyl protease, a pol gene which encodes reverse transcriptase and endonuclease, and the regulatory gene elements tax and rex. Regions within the LTR contain recognition sites for cellular proteins and the tax gene product that collectively promote viral expression. Tax-mediated activation of cellular genes involved in growth and differentiation is suspected to play a dominant role in the leukaemogenic process associated with HTLV-I infection. Differential rex-regulated splicing of viral message gives rise to transcripts encoding the polyprotein precursor gag-pro-pol (unspliced), envelope (single spliced), or tax/rex (doubly spliced). The 100nm HTLV virion contains an electron-dense core surrounding a divalent-single stranded DNA genome. This core is in turn enclosed by concentric shells of matrix protein and an outer lipid bilayer, the latter acquired as the virus buds from the surface of the infected cell. Envelope glycoproteins associated with the outside of this lipid bilayer can interact with viral receptors on cells and mediate virus entry. Antiviral strategies have been directed at inhibiting viral entry into cells (sulphated and non-sulphated polysaccharides, vaccines), blocking of viral replication (AZT, suramin), intracellular immunization (transdominant repression of rex), and elimination of virus infected cells (IL-2 receptor-directed toxins). Serological screening of the blood supply and curtailing breast feeding of children by HTLV-I + mothers have likely had a major impact in preventing HTLV-I infection.

The discovery of HTLV-1, the first pathogenic human retrovirus

After the discovery of retroviral reverse transcriptase in 1970, there was a flurry of activity, sparked by the "War on Cancer," to identify human cancer retroviruses. After many false claims resulting from various artifacts, most scientists abandoned the search, but the Gallo laboratory carried on, developing both specific assays and new cell culture methods that enabled them to report, in the accompanying 1980 PNAS paper, identification and partial characterization of human T-cell leukemia virus (HTLV; now known as HTLV-1) produced by a T-cell line from a lymphoma patient. Follow-up studies, including collaboration with the group that first identified a cluster of adult T-cell leukemia (ATL) cases in Japan, provided conclusive evidence that HTLV was the cause of this disease. HTLV-1 is now known to infect at least 4-10 million people worldwide, about 5% of whom will develop ATL. Despite intensive research, knowledge of the viral etiology has not led to improvement in treatment or outcome of ATL. However, the technology for discovery of HTLV and acknowledgment of the existence of pathogenic human retroviruses laid the technical and intellectual foundation for the discovery of the cause of AIDS soon afterward. Without this advance, our ability to diagnose and treat HIV infection most likely would have been long delayed.

Roles of HTLV-1 basic Zip Factor (HBZ) in Viral Chronicity and Leukemic Transformation. Potential New Therapeutic Approaches to Prevent and Treat HTLV-1-Related Diseases

More than thirty years have passed since human T-cell leukemia virus type 1 (HTLV-1) was described as the first retrovirus to be the causative agent of a human cancer, adult T-cell leukemia (ATL), but the precise mechanism behind HTLV-1 pathogenesis still remains elusive. For more than two decades, the transforming ability of HTLV-1 has been exclusively associated to the viral transactivator Tax. Thirteen year ago, we first reported that the minus strand of HTLV-1 encoded for a basic Zip factor factor (HBZ), and since then several teams have underscored the importance of this antisense viral protein for the maintenance of a chronic infection and the proliferation of infected cells. More recently, we as well as others have demonstrated that HBZ has the potential to transform cells both in vitro and in vivo. In this review, we focus on the latest progress in our understanding of HBZ functions in chronicity and cellular transformation. We will discuss the involvement of this paradigm shift of HTLV-1 research on new therapeutic approaches to treat HTLV-1-related human diseases.

Relevance of molecular tests for HTLV-1 infection as confirmatory tests after the first sero-screening

The diagnosis of human T-cell leukemia virus type-1 (HTLV-1) infection has been widely examined by serologics. In the first screening tests, serological false negative and positive samples have been reduced thanks to advances in assay techniques that apply new emission agents and sensors. On the other hand, western blot (WB) remains problematic. For example, WB analysis yields many samples equivalent to antibody positive ones. To reduce the need for WB, an alternative testing strategy is required to detect HTLV-1 infection. Polymerase chain reaction (PCR) for the HTLV-1 provirus has recently been recommended for a final diagnosis of infection. However, although PCR is thought to be one element, the validation of detection performance for HTLV-1 infection between serological and molecular testing is not always clear. Thus, this study aimed to evaluate the accuracy and test the validity of an improved methodology for serological detection of HTLV-infection, as well as that of PCR. In conclusion, the high values of kappa-statistics are expected to deliver high quality in chemiluminescent enzyme immunoassay (or chemiluminescent immunoassay), while the problems with WB assays remain to be elucidated. As an alternative to WB, a combination of real-time qPCR and nested PCR is proposed as a suitable confirmatory test.

Role of infectious agents in cutaneous T-cell lymphoma: facts and controversies

The etiology of cutaneous T-cell lymphoma (CTCL) remains unknown, with potential infectious causes having been explored. This contribution evaluates the evidence suggesting an infectious etiology and pathogenesis of the disease, characterizes the relationships between various specific pathogens and CTCL, and discusses some of the difficulties in establishing a causal link between infectious agents and CTCL carcinogenesis. Researchers have evaluated CTCL specimens for evidence of infection with a variety of agents, including human T-lymphotropic virus, Epstein-Barr virus, human herpesvirus-8, and Staphylococcus aureus, although other pathogens also have been detected in CTCL. Although there is significant evidence implicating one or more infectious agents in CTCL, studies to date have not linked definitively any pathogen to disease development, and various studies have yielded conflicting results.

HTLV-1 Rex: the courier of viral messages making use of the host vehicle

The human T-cell leukemia virus type 1 (HTLV-1) is a retrovirus causing an aggressive T-cell malignancy, adult T-cell leukemia (ATL). Although HTLV-1 has a compact RNA genome, it has evolved elaborate mechanisms to maximize its coding potential. The structural proteins Gag, Pro, and Pol are encoded in the unspliced form of viral mRNA, whereas the Env protein is encoded in singly spliced viral mRNA. Regulatory and accessory proteins, such as Tax, Rex, p30II, p12, and p13, are translated only from fully spliced mRNA. For effective viral replication, translation from all forms of HTLV-1 transcripts has to be achieved in concert, although unspliced mRNA are extremely unstable in mammalian cells. It has been well recognized that HTLV-1 Rex enhances the stability of unspliced and singly spliced HTLV-1 mRNA by promoting nuclear export and thereby removing them from the splicing site. Rex specifically binds to the highly structured Rex responsive element (RxRE) located at the 3' end of all HTLV-1 mRNA. Rex then binds to the cellular nuclear exporter, CRM1, via its nuclear export signal domain and the Rex-viral transcript complex is selectively exported from the nucleus to the cytoplasm for effective translation of the viral proteins. Yet, the mechanisms by which Rex inhibits the cellular splicing machinery and utilizes the cellular pathways beneficial to viral survival in the host cell have not been fully explored. Furthermore, physiological impacts of Rex against homeostasis of the host cell via interactions with numerous cellular proteins have been largely left uninvestigated. In this review, we focus on the biological importance of HTLV-1 Rex in the HTLV-1 life cycle by following the historical path in the literature concerning this viral post-transcriptional regulator from its discovery to this day. In addition, for future studies, we discuss recently discovered aspects of HTLV-1 Rex as a post-transcriptional regulator and its use in host cellular pathways.

Viral infections and human cancers: the legacy of Denis Burkitt

Denis Parsons Burkitt was born in 1911, and in the late 1950s, described the disease that has come to be known as Burkitt lymphoma based on cases he observed in Uganda. Subsequently, Burkitt lymphoma was recognized as the first human tumour associated with an infectious agent when Epstein-Barr virus was isolated from samples supplied by Burkitt. It is now recognized that over one-quarter of cancers worldwide are tied to infections. Notably, liver cancer is linked to hepatitis B virus and hepatitis C virus infections, and cervical cancer to infections involving the human papilloma viruses. In addition, immunocompromise arising from infection with the human immunodeficiency virus allows tumours (e.g., Kaposi sarcoma) caused by other viruses to arise. More than 50 years after the seminal paper by Burkitt based on his work in Africa, it is appreciated that the contribution of viral infections to cancers remains considerably higher in sub-Saharan Africa than in the rest of the world.

Programmed death-1 (PD-1)/PD-1 ligand pathway-mediated immune responses against human T-lymphotropic virus type 1 (HTLV-1) in HTLV-1-associated myelopathy/tropical spastic paraparesis and carriers with autoimmune disorders

Human T-lymphotropic virus-1 (HTLV-1) causes HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP) and adult T-cell leukemia-lymphoma in individuals with dysfunctional immune responses. In this study, to characterize the HTLV-1-specific cytotoxic T lymphocyte (CTL) populations in asymptomatic HTLV-1 carriers (ACs), HAM/TSP patients, and carriers with autoimmune disorders (CAIDs), we examined the role of programmed death-1 and its ligand (PD-1/PD-L1) in HTLV-1-specific CTL functions using an HTLV-1 Tax/HLA-A*0201 tetramer and an HTLV-1 Tax/HLA-A*2402 tetramer. Interestingly, the percentage of HTLV-1 Tax301-309/HLA-A*2402 tetramer(+)CD8(+) cells expressing PD-1 in ACs was significantly higher than the percentage of HTLV-1 Tax11-19/HLA-A*0201 tetramer(+)CD8(+) cells expressing PD-1. PD-1 expression was significantly downregulated on HTLV-1-specific CTLs in HAM/TSP compared with ACs. PD-L1 expression was observed in a small proportion of unstimulated lymphocytes from ACs and was greater in ACs than in HAM/TSP and CAIDs after short-term culture. Furthermore, CTL degranulation was impaired in HAM/TSP, whereas anti-PD-L1 blockade significantly increased CTL function in ACs. Downregulation of PD-1 on HTLV-1-specific CTLs and loss of PD-L1 expression in HAM/TSP and CAIDs, along with impaired function of HTLV-1-specific CTLs in HAM/TSP, may underlie the apparently dysfunctional immune response against HTLV-1.

Evaluation of the effects of Quercetin and Kaempherol on the surface of MT-2 cells visualized by atomic force microscopy

This study investigated the anti-viral effects of the polyphenolic compounds Quercetin and Kaempherol on the release of HTLV-1 from the surface of MT-2 cells. Atomic force microscopy (AFM) was used to scan the surface of the MT-2 cells. MT-2 cells were fixed with 100% methanol on round glass lamina or cleaved mica and dried under UV light and laminar flow. The images were captured on a Multimode equipment monitored by a NanoScope IIId controller from Veeco Instruments Inc operated in tapping mode and equipped with phase-imaging hardware. The images demonstrated viral budding structures 131 ± 57 nm in size, indicating profuse viral budding. Interestingly, cell-free viruses and budding structures visualized on the surface of cells were less common when MT-2 was incubated with Quercetin, and no particles were seen on the surface of cells incubated with Kaempherol. In summary, these data indicate that HTLV-1 is budding constantly from the MT-2 cell surface and that polyphenolic compounds were able to reduce this viral release. Biological samples were analyzed with crude cell preparations just after cultivation in the presence of Quercetin and Kaempherol, showing that the AFM technique is a rapid and powerful tool for analysis of antiviral activity of new biological compounds.

Ethnoepidemiology of HTLV-1 related diseases: ethnic determinants of HTLV-1 susceptibility and its worldwide dispersal

Human T-cell lymphotropic virus type 1 is vertically transmitted in neonatal life and is causatively associated with adult T-cell leukemia (ATL) and HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP) in adults. Persistence of HTLV-1 in host T cells, clonal expansion of the HTLV-1 carrying T cells, and emergence of malignantly transformed T cells are in accord with the multistep model of human cancer and roles for continuous interaction between host genes and environmental factors. This article reviews two lines of HTLV-1 investigation, one regarding worldwide surveillance of HTLV-1 infection foci by serological testing and molecular analysis of HTLV-1 isolates, and the other focusing on genetics of the human leukocyte antigen (HLA) that determines the ethnic background of HTLV-1 permissiveness and susceptibility to ATL or HAM/TSP. The serological surveillance revealed transcontinental dispersal of HTLV-1 in the prehistoric era that started out of Africa, spread to Austro-Melanesia and the Asian continent, then moved to North America and through to the southern edge of South America. This was highlighted by an Andean mummy study that proved ancient migration of paleo-mongoloid HTLV-1 from Asia to South America. Phylogenetic analysis of HLA alleles provided a basis for ethnic susceptibility to HTLV-1 infection and associated diseases, both ATL and HAM/TSP. Ethnicity-based sampling of peripheral blood lymphocytes has great potential for genome-wide association studies to illuminate ethnically defined host factors for viral oncogenesis with reference to HTLV-1 and other pathogenic elements causatively associated with chronic disease and malignancies.

Thioredoxin-binding protein-2 (TBP-2/VDUP1/TXNIP) regulates T-cell sensitivity to glucocorticoid during HTLV-I-induced transformation

Although glucocorticoid (GC) is widely used for treating hematopoietic malignancies including adult T-cell leukemia (ATL), the mechanism by which leukemic cells become resistant to GC in the clinical course remains unclear. Using a series of T-cell lines infected with human T lymphotropic virus type-I (HTLV-I), the causative virus of ATL, we have dissected the transformation from interleukin (IL)-2-dependent to -independent growth stage. The transformation associates the loss of thioredoxin-binding protein-2 (TBP-2), a tumor suppressor and regulator of lipid metabolism. Here we show that TBP-2 is responsible for GC-induced apoptosis in ATL cells. In the IL-2-dependent stage, dexamethasone induced TBP-2 expression and apoptosis, both of which were blocked by GC receptor (GR) antagonist RU486. Knockdown of TBP-2 consistently reduced the amount of GC-induced apoptosis. In IL-2-independent stage, however, expression of GR and TBP-2 was suppressed and GC failed to induce apoptosis. Forced expression of GR led the cells to mild sensitivity to GC, which was also accomplished by treatment with suberoylanilide hydroxamic acid, a TBP-2 inducer. A transfection experiment showed that TBP-2 expression induced apoptosis in IL-2-independent ATL cells. Thus, TBP-2 is likely to be one of the key molecules for GC-induced apoptosis and a potential target for treating the advanced stage of ATL.

Differential roles of Annexin A1 (ANXA1/lipocortin-1/lipomodulin) and thioredoxin binding protein-2 (TBP-2/VDUP1/TXNIP) in glucocorticoid signaling of HTLV-I-transformed T cells

Glucocorticoid (GC) is widely used for therapeutic purposes in immunological and hematological disorders. Annexin A1 (ANXA1/lipocortin-1/lipomodulin), a GC-inducible molecule, was regarded as a vital anti-inflammatory mediator of GC. Thioredoxin binding protein-2 (TBP-2/VDUP1/TXNIP), a regulator of redox reactions, cell growth and lipid metabolism, was also reportedly induced by GC. HTLV-I infected T cells undergo the transition from the IL-2 dependent to IL-2 independent growth during the long-term culture in vitro. We found that these T cells responded to GC with growth arrest and apoptosis in the IL-2 dependent growth stage, whereas they failed to respond to GC after their growth had shifted into the IL-2 independent stage. Here we employed these T cell lines and studied the roles of ANXA1 and TBP-2 in mediating GC-induced apoptosis. In GC-sensitive T cells, ANXA1 expression was negligible and unaffected by GC treatment, whereas TBP-2 was expressed and induced by GC treatment. In GC-resistant T cells, however, ANXA1 was highly expressed regardless of GC treatment and promoted cellular proliferation. In contrast, TBP-2 expression was lost and could not mediate the GC-induced apoptosis. In conclusion, these results suggest that TBP-2, but not ANXA1, is directly involved in the switching of GC sensitivity and GC resistance in HTLV-I infected T cell lines, whereas ANXA1 may be a biomarker indicative of the advanced stage of the transformation.

Performance of IgG and IgG1 anti-HTLV-1 reactivity by an indirect immunofluorescence flow cytometric assay for the identification of persons infected with HTLV-1, asymptomatic carriers and patients with myelopathy

In this study, the performance of IgG and IgG1 anti-HTLV-1 reactivity obtained by a flow cytometric assay was evaluated to verify its applicability for the diagnosis of persons infected with HTLV-1, including asymptomatic carriers and patients with myelopathy. The ability to identify patients with myelopathy among persons infected with HTLV-1 was also examined. Western blot assays were performed to assess the reactivity profiles of sera from asymptomatic carriers and patients with myelopathy against viral proteins. The data showed that IgG1 detected by flow cytometric assay is effective for the diagnosis of persons infected with HTLV-1 with 97% sensitivity and 100% specificity. IgG and IgG1 exhibited high performance in distinguishing patients with myelopathy from asymptomatic carriers. Using serum dilutions and cut-off points established previously a second HTLV-1 carrier group was tested using flow cytometric assay to detect IgG and IgG1. The data demonstrated sensitivity of 93% and 98%, respectively, confirming the high reactivity of persons infected with HTLV-1 detected by this method. Western blot assays confirmed the high specificity of MT-2 cells as a reliable source of viral antigen since only sera from persons infected with HTLV-1 recognised MT-2 proteins. Furthermore, a high reactivity to Gag and Env proteins was observed, especially among patients with myelopathy. These data suggest that flow cytometric detection of IgG1 is a valuable, non-conventional serological method to diagnose HTLV-1 infection and for research purposes.

A historical reflection on the discovery of human retroviruses

The discovery of HIV-1 as the cause of AIDS was one of the major scientific achievements during the last century. Here the events leading to this discovery are reviewed with particular attention to priority and actual contributions by those involved. Since I would argue that discovering HIV was dependent on the previous discovery of the first human retrovirus HTLV-I, the history of this discovery is also re-examined. The first human retroviruses (HTLV-I) was first reported by Robert C. Gallo and coworkers in 1980 and reconfirmed by Yorio Hinuma and coworkers in 1981. These discoveries were in turn dependent on the previous discovery by Gallo and coworkers in 1976 of interleukin 2 or T-cell growth factor as it was called then. HTLV-II was described by Gallo's group in 1982. A human retrovirus distinct from HTLV-I and HTLV-II in that it was shown to have the morphology of a lentivirus was in my mind described for the first time by Luc Montagnier in an oral presentation at Cold Spring Harbor in September of 1983. This virus was isolated from a patient with lymphadenopathy using the protocol previously described for HTLV by Gallo. The first peer reviewed paper by Montagnier's group of such a retrovirus, isolated from two siblings of whom one with AIDS, appeared in Lancet in April of 1984. However, the proof that a new human retrovirus (HIV-1) was the cause of AIDS was first established in four publications by Gallo's group in the May 4^th issue of Science in 1984.

PD-1/PD-L1 expression in human T-cell leukemia virus type 1 carriers and adult T-cell leukemia/lymphoma patients

Adult T-cell leukemia/lymphoma (ATLL) develops after infection with human T-cell leukemia virus-1 (HTLV-1) after a long latency period. The negative regulatory programmed death-1/programmed death-1 ligand 1 (PD-1/PD-L1) pathway has been implicated in the induction of cytotoxic T-lymphocyte (CTL) exhaustion during chronic viral infection along with tumor escape from host immunity. To determine whether the PD-1/PD-L1 pathway could be involved in the establishment of persistent HTLV-1 infections and immune evasion of ATLL cells in patients, we examined PD-1/PD-L1 expression on cells from 27 asymptomatic HTLV-1 carriers (ACs) and 27 ATLL patients in comparison with cells from 18 healthy donors. PD-1 expression on HTLV-1-specific CTLs from ACs and ATLL patients was dramatically elevated. In addition, PD-1 expression was significantly higher on CD8+ T cells along with cytomegalovirus (CMV)- and Epstein-Barr virus (EBV)-specific CTLs in ATLL patients compared with ACs and control individuals. Primary ATLL cells in 21.7% of ATLL patients expressed PD-L1, whereas elevated expression was not observed in cells from ACs. Finally, in functional studies, we observed that an anti-PD-L1 antagonistic antibody upregulated HTLV-1-specific CD8+T-cell response. These observations suggest that the PD-1/PD-L1 pathway plays a role in fostering persistent HTLV-1 infections, which may further ATLL development and facilitate immune evasion by ATLL cells.

Chapter 9 Infections caused by rubella, reoviridae, retro, Norwalk and ronaviruses

This chapter focuses on infections caused by rubella, reoviridae, retro, Norwalk and coronaviruses. High incidence of acute gastroenteritis caused by rotaviruses calls for prophylactic and therapeutic measures. Although no vaccine is presently available, it seems likely that vaccines will be developed in the next few years. There are also several rotavirus enzymes useful as targets for antiviral drugs. However, no antiviral drugs have shown therapeutic effects against rotavirus infections. The newly discovered human retrovirus (HTLV) has not yet been investigated in such detail as to predict the usefulness of vaccine or antiviral drugs. Several compounds are known to inhibit other retrovirus enzymes but the implication of this for chemotherapy of HTLV infection is unknown at present. The possibility and need for vaccination or chemotherapy against Norwalk virus and related agents is unclear. Very little work has been carried out to date with human coronaviruses, either from the point of view of vaccine development or specific antivirals. Both approaches may be usefully investigated in the future. Genetic cloning may be particularly useful for development of inactivated vaccines because the virus itself would be difficult to replicate and purify in large quantities for conventional vaccines.

[Evaluation of the performance of immunological parameters as indicators for clinical progression of chronic HTLV-1 infection]

This study evaluated the performance of single and combined laboratory parameters, B-lymphocyte percentages (%LB), T/B cell ratio and %CD8+HLA-DR+/CD8+, to differentiate asymptomatic cases (AS) from HAM/TSP patients (HT) within a population of HTLV-1 seropositive cases. Percentage indices demonstrated that each parameter alone presented moderate performance, with co-negativity of 83 and 91% for %LB and T/B cell ratio, respectively, and co-positivity of 78% for %CD8+HLA-DR+/CD8+. Combined analysis (%CD8+HLA-DR+/CD8+ and T/B cell ratio) did not show any substantial performance enhancement (co-positivity = 75% and co-negativity = 74%). Likelihood ratio analysis using different value ranges for the separate parameters revealed that HTLV-1 seropositive cases with %LB<7%, T/B cell ratio>11 and %CD8+HLA-DR+/CD8+>70% would have, respectively, 11, 19 and 10 times greater chance of belonging to the HT group. Therefore, use of these phenotypic indicators as complementary laboratory methods for monitoring the clinical progression of chronic HTLV-1 infection is recommended.

IL-10 produced by CD4+ and CD8+ T cells emerge as a putative immunoregulatory mechanism to counterbalance the monocyte-derived TNF-alpha and guarantee asymptomatic clinical status during chronic HTLV-I infection

Although it is believed widely that distinct patterns of the host immune response are associated with the outcome of chronic human T cell lymphotropic virus type 1 (HTLV-I) infection toward asymptomatic or symptomatic neurodegenerative myelopathy (HAM/TSP), the exact mechanism underlying these immunological events still remains unknown. In this study, we have evaluated the cytokine pattern [interleukin (IL)-12, interferon (IFN)-gamma, tumour necrosis factor (TNF)-alpha, IL-4 and IL-10] of innate and adaptive immunity cells present at the peripheral blood from non-infected (NI) and HTLV-I infected individuals [asymptomatic (AS), oligosymptomatic (OL) and HAM/TSP-HT], following in vitro short-term incubation in the absence/presence of phorbol myristate acetate (PMA) pan-leucocyte stimulation. In the absence of PMA stimulation, our data demonstrate that despite the overall immunological profile of AS mimicry that observed for NI, the high frequency of IL-12(+) neutrophils and TNF-alpha(+) monocytes are also a hallmark of this group of individuals. However, the outstanding positive correlation between the high frequency of TNF-alpha(+) monocytes and high levels CD4(+) IL-10(+) and CD8(+) IL-10(+) T cells suggests the establishment of immunoregulatory mechanisms that guarantee their asymptomatic clinical status. On the other hand, OL and HT did not present any association between the high frequency and TNF-alpha(+) neutrophils and monocytes and this immunoregulatory profile at their adaptive immunity cells. Upon PMA-index analysis, high levels of type 1 CD4(+) T cells, as well as higher IFN-gamma/IL-10 and TNF-alpha/IL-10 ratios, were observed in HT, and re-emphasize the role of Th1-cytokines from CD4(+) cells to HTLV-I immunity and disease. Moreover, increasing frequency of CD8(+) IFN-gamma(+) and CD8(+) TNF-alpha(+) cells were observed in the HT, which corroborates the marked inflammatory profile underlying this pathological condition and the role of CD8(+) T cells in the pathogenesis of HAM/TSP.

Reduced frequency, diversity, and function of human T cell leukemia virus type 1-specific CD8+ T cell in adult T cell leukemia patients

Human T cell lymphotropic virus type 1 (HTLV-1)-specific CTL are thought to be immune effectors that reduce the risk of adult T cell leukemia (ATL). However, in vivo conditions of anti-HTLV-1 CTL before and after ATL development have yet to be determined. To characterize anti-HTLV-1 CTL in asymptomatic HTLV-1 carriers (AC) and ATL patients, we analyzed the frequency and diversity of HTLV-1-specific CD8+ T cells in PBMC of 35 AC and 32 ATL patients using 16 distinct epitopes of HTLV-1 Tax or Env/HLA tetramers along with intracellular cytolytic effector molecules (IFN-gamma, perforin, and granzyme B). Overall frequency of subjects possessing Tax-specific CD8+ T cells was significantly lower in ATL than AC (53 vs 90%; p = 0.001), whereas the difference in Env-specific CD8+ T cells was not statistically significant. AC possessed Tax11-19/HLA-A*0201-specific tetramer+ cells by 90% and Tax301-309/HLA-A*2402-specific tetramer+ cells by 92%. Some AC recognized more than one epitope. In contrast, ATL recognized only Tax11-19 with HLA-A*0201 and Tax301-309 with HLA-A*2402 at frequencies of 30 and 55%. There were also significant differences in percentage of cells binding Tax11-19/HLA-A*0201 and Tax301-309/HLA-A*2402 tetramers between AC and ATL. Anti-HTLV-1 Tax CD8+ T cells in AC and ATL produced IFN-gamma in response to Tax. In contrast, perforin and granzyme B expression in anti-HTLV-1 CD8+ T cells of ATL was significant lower than that of AC. Frequency of Tax-specific CD8+ T cells in AC was related to proviral load in HLA-A*0201. These results suggest that decreased frequency, diversity, and function of anti-HTLV-1 Tax CD8+ T cell clones may be one of the risks of ATL development.

Development of lupus nephritis in a patient with human T-cell lymphotropic virus type I-associated myelopathy

A 77-year-old Japanese man with a 14-year history of human T-cell lymphotropic virus type I-associated myelopathy developed pancytopenia, proteinuria, renal dysfunction, and hypocomplementemia. Antinuclear antibody and anti-double-stranded DNA antibody test results were positive, and circulating immune complexes were detected. A renal biopsy showed diffuse and global mesangiocapillary proliferation with extensive subendothelial deposits. Immunofluorescence microscopy showed strong granular staining for immunoglobulins and complements in the mesangium and along capillary walls. Electron microscopy showed numerous mesangial and subendothelial electron-dense deposits. From these findings, systemic lupus erythematosus and diffuse global lupus nephritis were diagnosed. This is a rare case of a patient developing lupus nephritis during the long-term course of human T-cell lymphotropic virus type I-associated myelopathy.

The discovery of the first human retrovirus: HTLV-1 and HTLV-2

I describe here the history leading up to and including my laboratory's discovery of the first human retrovirus, HTLV-I, and its close relative, HTLV-II. My efforts were inspired by early work showing a retroviral etiology for leukemias in various animals, including non-human primates. My two main approaches were to develop criteria for and methods for detection of viral reverse transcriptase and to identify growth factors that could support the growth of hematopoietic cells. These efforts finally yielded success following the discovery of IL-2 and its use to culture adult T cell lymphoma/leukemia cells.

Establishing phenotypic features associated with morbidity in human T-cell lymphotropic virus type 1 infection

The human T-cell lymphotropic virus type 1 (HTLV-1) is the causative agent of HTLV-1-associated myelopathy/tropical spastic paraparesis (HT). Although it is widely believed that virus infection and host immune response are involved in the pathogenic mechanisms, the role of the immune system in the development and/or maintenance of HT remains unknown. We performed an analysis of the peripheral blood leukocyte phenotype for two different subcohorts of HTLV-1-infected individuals to verify the existence of similar immunological alterations, possible laboratory markers for HT. The leukocyte population balance, the activation status of the T lymphocytes, and the cellular migratory potential of T lymphocytes, monocytes, and neutrophils were evaluated in the peripheral blood of HTLV-1-infected individuals classified as asymptomatic individuals, oligosymptomatic individuals, and individuals with HT. Data analysis demonstrated that a decreased percentage of B cells, resulting in an increased T cell/B cell ratio and an increase in the CD8+ HLA-DR+ T lymphocytes, exclusively in the HT group could be identified in both subcohorts, suggesting its possible use as a potential immunological marker for HT for use in the laboratory. Moreover, analysis of likelihood ratios showed that if an HTLV-1-infected individual demonstrated B-cell percentages lower than 7.0%, a T cell/B cell ratio higher than 11, or a percentage of CD8+ HLA-DR+ T lymphocytes higher than 70.0%, this individual would have, respectively, a 12-, 13-, or 22-times-greater chance of belonging to the HT group. Based on these data, we propose that the T cell/B cell ratios and percentages of circulating B cells and activated CD8+ T lymphocytes in HTLV-1-infected patients are important immunological indicators which could help clinicians monitor HTLV-1 infection and differentiate the HT group from the asymptomatic and oligosymptomatic groups.

Human T-cell leukemia virus type I infection in various recipients of transplants from the same donor

BACKGROUND

The human T-cell lymphotrophic virus (HTLV) causes adult T-cell leukemia-lymphoma, tropical spastic paraparesis-HTLV type I, and associated myelopathy.

METHODS

An analysis was performed of serum samples from a multiorgan donor and the five recipients. Also studied was the donor's family and the partner of one of the renal recipients. Serologic detection of anti-HTLV antibodies was carried out by enzyme immunoassay and Western blot to confirm and discriminate between HTLV types. Analysis of proviral DNA was performed by polymerase chain reaction and sequenced in the long terminal repeat region and the env gene. Peripheral blood mononuclear cell samples from all the recipients of the HTLV-I-positive organs and the donor's mother were studied.

RESULTS

Two years after transplantation, three organ recipients positive for antibodies to HTLV-I were detected (two kidney transplants and one liver). All the recipients' serum samples were negative at the time of transplantation except those from the multiorgan donor. The donor's mother was born in Venezuela and was confirmed positive for antibodies to HTLV-I. The remaining family members were negative. HTLV-I DNA sequences were recovered, amplified, and sequenced from all the samples from the HTLV-I-positive recipients and the donor's mother. The homology of HTLV-I sequences was 100% in all cases.

CONCLUSIONS

The authors are reporting the first documented case of HTLV-I infection in several transplant recipients sharing the same donor. The donor was infected by vertical transmission. HTLV-I infection has devastating consequences for some immunocompromised organ recipients. This emphasizes the need for a systematic survey of HTLV antibodies in all potential donors.

Human T-cell lymphotrophic virus infection in organ donors: a need to reassess policy?

Human T-cell lymphotrophic virus (HTLV)-I/II infection has been considered a contra-indication to organ donation due to the risk of transmission of infection and the subsequent development of either adult T-cell leukemia or HTLV-I-associated myelopathy. However, neither the incidence of HTLV-I/II infection in organ donors nor the risk of transmission of HTLV-I/II by solid organ transplantation has been defined. Further, it is not known if HTLV infection contributes to significant morbidity in solid organ recipients. The purpose of this study was to evaluate the incidence of HTLV-I/II infection in organ donors in USA and to determine if transplanting these organs resulted in HTLV-related morbidity or mortality. We utilized the UNOS database to: (i) identify organ donors that were positive for HTLV-I or II infection between 1988 and 2000, and (ii) evaluate outcomes in the recipients of these organs. There were 25 HTLV-I/II-positive organ donors reported to UNOS between 1988 and 2000. Based on organ donors with a known HTLV-I/II status, the prevalence of HTLV-I infection in organ donors is 0.027% and the prevalence of HTLV-II is 0.064%. Twenty-two organs were transplanted from these HTLV-positive donors. There have been no reports of HTLV-I/II-related disease in the recipients with a median follow-up of 11.9 months. At our center, over the last 1.5 years there have been four multiorgan donors with false-positive HTLV-I/II screening assays, which resulted in the decision not to use organs from these donors. Based on the minimal chance of HTLV-related disease following transplantation of HTLV-I/II organs in this series, we recommend that careful consideration be given to transplanting organs from HTLV-I/II-positive organ donors.

Human retroviruses after 20 years: a perspective from the past and prospects for their future control

Among viruses the human retroviruses may be of special interest to immunologists, because they target cells of the immune system, particularly mature CD4+ T cells, impair their function and cause them to grow abnormally (human T-cell leukemia virus, HTLV) or to die (human immunodeficiency virus, HIV). Human retroviruses cause disease ranging from neurological disorders and leukemias (HTLV-1) to AIDS (acquired immunodeficiency virus) (HIV) and promote development of several types of malignancies (HIV). They share many common features, but their contrasts are greater, especially the far greater replication and variation of HIV associated with its greater genomic complexity. Both have evolved striking redundancy for mechanisms which promote their survival. Thus, HTLV has redundant mechanisms for promoting growth of provirus containing T cells needed for virus continuity, because it is chiefly through its cellular DNA provirus that HTLV replicates and not through production of virions. Conversely, HIV has redundancy in its mechanisms for promoting virion replication and escape from the host immune system. It is via these redundant mechanisms that they produce disease: leukemias from mechanisms promoting T-cell proliferation (HTLV-1) and AIDS from mechanisms promoting virus replication and T-cell death (HIV). The practical challenges for the future are clear. For HTLV-1, education and control of breastfeeding. For HIV, the formidable tasks now ahead in part demand new kinds of talent, talents that will foster greater insights into the development of therapy for the developing countries, new forms of less toxic therapies for all infected persons, a continued and expanded commitment to education, and a persistent 'never say die' commitment to the development of a truly preventive vaccine with all the scientific and nonscientific challenges that these objectives face.

Phenotypic study of peripheral blood leucocytes in HTLV-I-infected individuals from Minas Gerais, Brazil

The human T-cell lymphotropic virus type I (HTLV-I)-associated myelopathy/tropical spastic paraparesis (HAM/TSP) associated with the HTLV-I is a well-defined clinical-pathological entity in which the virus and host immune responses contribute to the pathological mechanism. In this study, flow cytometric analysis of whole peripheral blood leucocytes (PBL) was performed to evaluate the immunological status of HTLV-I-infected individuals in an effort to better understand the role of the immune system in the development of HAM/TSP. We have evaluated three groups of infected patients including asymptomatic (AS = 18), ambulatory/oligosymptomatic (AM = 14) and hospitalized HAM/TSP individuals (HO = 42). Noninfected healthy blood donors were used for the control group (NI = 32). Our results demonstrated that the HO group presents an increased percentage of circulating T cells and a decreased percentage of B and natural killer (NK) cells, leading to the highest T/B-cell ratio in comparison with the other groups. Interestingly, while an increased percentage of activated CD4+HLA-DR+ T lymphocytes was observed in both AM and HO, only HO presented higher percentage of activated CD8+HLA-DR+ in combination with the highest CD18 surface expression. This was true for all cell populations analysed, including T lymphocytes, monocytes and neutrophils. Moreover, the HO group was distinguished by a dramatic decrease in the percentage of CD8+CD28+ lymphocytes. Taken together, these findings demonstrate a potent cellular immune activation response involving primarily CD8+ T cells that is concomitant with disease progression in HAM/TSP. We also show that an upregulation of CD18 expression, a hallmark for increased cell migratory potential, might play a critical role in the development/maintenance of HAM/TSP.

HTLV-I transmission from mother to child

Human T-lymphotropic virus type I (HTLV-I), a causative agent of adult T-cell leukemia, (ATL) is transmitted from mother to child. ATL cells originate from the CD4 subset of peripheral T cells. The main route of mother-to-child transmission is postnatal breast-feeding. Refraining from breast-feeding or limiting the duration of breast-feeding can reduce the risk of mother-to-child transmission. Other than postnatal breast-feeding, there seem to be two routes of HTLV-I transmission from mother to child. One is intrauterine transmission, and the other is via saliva. Intrauterine transmission is rare, although proviral DNA is detected in cord blood samples. HTLV-I proviruses in the cord blood may be defective. HTLV-I proviral DNA and antibodies against HTLV-I are also detected in saliva. However, no report has been published so far which showed direct evidence of HTLV-I transmission via saliva. The placenta can be infected by HTLV-I, but infection does not reach the fetus, possibly apoptosis of placental villous cells because it is induced by HTLV-I infection.

Human T-cell leukemia retrovirus-Tax protein is a repressor of nuclear receptor signaling

The Tax oncoprotein promotes cellular transformation and is associated with the pathogenesis of adult T-cell leukemia. Tax expression activates transcription via the cAMP enhancer binding protein/activating transcription factor (CREB/ATF) and NF-kappaB pathways. In contrast to its positive action, here we demonstrate that Tax is a potent repressor of steroid and retinoid receptor transcription. The Tax protein becomes localized in the promyelocytic (PML) oncogenic domain, and unexpectedly, expression of the PML protein reverses Tax-induced repression. These results suggest that PML and Tax may act in opposing manners to influence nuclear receptor transcription and human T-cell leukemia retrovirus pathogenesis.

Simian T cell leukemia virus type I-induced malignant adult T cell leukemia-like disease in a naturally infected African green monkey: implication of CD8+ T cell leukemia

Spontaneous T cell leukemia was found in an African green monkey (Cercopithecus aethiops, AGM) naturally infected with simian T cell leukemia virus type I (STLV-I). The hematological features and the evidence for monoclonal integration of provirus DNA in the leukemic cells revealed that the leukemia was an ATL-like disease. The expression of surface markers on the leukemic cells indicated that they were defined as an activated CD8+ T cell subset. Together with the finding that seven in vitro spontaneously STLV-I-transformed cell lines were CD4-CD8+, it is likely that CD8+ T cells are transformed by STLV-I in AGMs, in contrast with human ATL. Finally, we assessed characteristics of the CD8 chains on these transformed cells. The result indicated that the leukemic cells expressed only the alpha chains but not the beta chains. However, in the case of in vitro-transformed cell lines the expression pattern of the CD8 chains varied in individual monkeys. Thus, STLV-I may preferentially transform CD8+ (both alphaalpha+ and alphabeta+) T cells in AGMs.

Prophylaxis of experimental HTLV-I infection in cynomolgus monkeys by passive immunization

The protective effect of purified human immunoglobulin against human T-cell leukaemia virus type I (HTLV-I), designated ATLIG on HTLV-I infection was examined in cynomolgus monkeys (Macaca fascicularis) as a preclinical study. Passive immunization of ATLIG 24 h before challenging HTLV-I protected the monkeys from HTLV-I infection. The result suggests that passive immunization of ATLIG could provide safe and sufficient protection against HTLV-I infection in humans.

HTLV infection among Italian intravenous drug users and North African subjects detected by the polymerase chain reaction and serological methods

Six hundred intravenous drug users (IVDUs) and two hundred North Africans were screened for human T-cell leukemia virus (HTLV) antibodies using several serological methods. Eighteen of the eighty-two HTLV-seropositive individuals were also tested by the polymerase chain reaction-DNA enzyme immunoassay (PCR-DEIA), a non-isotopic method of immunoenzymatic detection of the amplified DNA. Of these eighteen subjects, eight IVDUs were found to be HTLV-II-positive by the PCR-DEIA, whereas all of the eighteen subjects were negative for HTLV-I. Western blot (WB) confirmed six of the eight HTLV-positive subjects, while the results of the remaining two were indeterminate. The results confirmed the PCR-DEIA as a rapid and an efficient method of discriminating between HTLV-I and HTLV-II infection, whereas serological tests, including the WB, have limitations in terms of specificity and sensitivity. Moreover, this study showed a higher frequency of HTLV seroreactivity in the Italian IVDU population than in previous studies and confirmed that HTLV-II is more frequent than HTLV-I in this population.

Stable human T-lymphotropic virus type I carrier rates for 7 years among a teenaged blood donor cohort of 1986 in Kumamoto, Japan

The human T-lymphotropic virus type I (HTLV-I) carrier rates for blood donors in Kumamoto, Kyushu, Japan for 8 years, 1986-1993, are currently available. The data show that 16-19-year-olds in 1986 and 20-29-year-olds in 1993 represent nearly the same cohort, because the median age in both groups is 24.5 years in 1993. Therefore, comparison of the HTLV-I positive rate for the two groups gives an estimate of the change in the rate over 7 years within the cohort. In males, 265 of 22,143 donors (1.20%) were seropositive for HTLV-I among 16-19-year-olds in 1986, and 214 were seropositive among 20,076 (1.07%) donors in 20-29-year-olds in 1993. In females, 203 were seropositive among 20,677 (0.98%) donors in 16-19-year-olds in 1986, and there 154 were seropositive among 18,660 (0.83%) donors in 20-29-year-olds in 1993. Thus, the seropositive rates declined in both sexes. However, the average annual rate of immigration to Kumamoto Prefecture was 2.37%. If seropositive rates for 20-29-year-olds in 1993 are adjusted for the dilution effect due to immigration (under the assumption that all immigrants were HTLV-I negative), the adjusted carrier rate for males is 1.26% and that for females is 0.98%. The adjusted carrier rates for both sexes are almost the same as those for 16-19-year-olds in 1986. This indicates that horizontal transmission was negligible for those in the cohort who were in their early reproductive period. Using all 8 year carrier rates for 16-19-year-olds and 20-29-year-olds, chronological changes of 20-29-year-olds, in the near future was estimated. The best goodness of fit model indicated that the HTLV-I carrier rate will decline exponentially, and that the rate will decrease by 50% approximately every 10 years for both sexes. It is probable that in recent years south-west Japan has lost the conditions that are favorable for HTLV-I endemicity and the virus will be virtually non-endemic within a few generations.

Adult T-cell leukaemia with various abnormalities in endocrine and metabolic systems

Adult T-cell leukaemia (ATL) is a unique type of T-cell malignancy closely associated with human T-cell leukaemia virus-1 (HTLV-1). Despite frequent descriptions of hypercalcaemia, cases accompanied by diabetes insipidus or syndrome of inappropriate secretion of anti-diuretic hormone (SIADH) in ATL patients have rarely been reported. We present an unusual case of ATL with various abnormalities in his endocrine and metabolic systems involving anterior pituitary function, thyroid function, lipid metabolism and Ca metabolism. Some of these abnormalities were considered to arise from infiltration or leukaemic cells into systemic organs after elimination of the above symptoms. Clinical and haematological data showing improvement following chemotherapy are also presented.

Human T lymphotropic virus type 1 uveitis

The human retroviruses, HTLV-I and HIV, are playing clinically important roles in a variety of ocular disorders, particularly in uveitis. Both viruses are integrated in the genome of infected T cells. HIV-I infection causes the death of the infected T cells, thereby affecting the host defence system and causing AIDS. Subsequent opportunistic infections of ocular tissues, such as CMV retinitis, are a serious problem in clinical ophthalmology all over the world. Another human retrovirus, HTLV-I, has been known as the causative agent of T cell malignancies (ATL and T cell lymphoma) and chronic myelopathy (HAM/TSP), and is now recognised as a causative agent for a specific type of intraocular inflammation characterised by vitreous opacities with mild iritis and mild retinal vasculitis (HTLV-I uveitis). The mechanism by which HTLV-I causes uveitis is still unknown, but our recent data suggest that it is most probably an immune mediated mechanism by activated CD4 T cells infected with the virus. HTLV-I uveitis, therefore, may implicate a significant role of retroviruses in autoimmune diseases and further the pathogenesis of diseases with infection/autoimmune overlap.