Epidemiological features of HTLV-I carriers and incidence of ATL in an ATL-endemic island: a report of the community-based co-operative study in Tsushima, Japan

Adult T-Cell Lymphoma (ATL) With Erythroderma in Indolent Human T-Lymphotropic Virus Type I (HTLV-1) Infection

Adult T-cell lymphoma (ATL) is a hematological malignancy of CD4+ mature T-lymphocytes commonly associated with chronic human T-lymphotropic virus type I (HTLV-1) infection. Chronic HTLV-1 infection induces oncogenic mutations in CD4+ T-cells, leading to an acute malignant transformation of host cells. Atypically, ATL presents with dermatological and pulmonary symptoms consistent with a "smoldering" disease pattern. We present a case of a 78-year-old male patient with chronic generalized malaise, progressively worsening shortness of breath, and diffuse erythroderma, who was diagnosed with ATL secondary to chronic indolent HTLV-1 infection. We evaluate the multisystemic clinical signs associated with ATL, the comprehensive clinical investigations required to reach a conclusive diagnosis, and the options for long-term clinical management.

Very high prevalence of infection with the human T cell leukaemia virus type 1c in remote Australian Aboriginal communities: Results of a large cross-sectional community survey

Infection with the human T cell leukaemia virus type 1 (HTLV-1) subtype C is endemic among Aboriginal people in central Australia. To provide insights into the risk factors for transmission, we conducted the first large-scale, community-based prevalence study in seven remote Aboriginal communities. Residents >2 years old were invited to participate in the study between August 2014 and June 2018. HTLV-1 infection was defined as a positive western blot (WB) test or a positive HTLV-1 PCR. 720 community residents participated in the study (children <15 years, 142; adults, 578). Prevalences for children and adults were 3.5% (5/142) and 36.8% (213/578), respectively, reaching 49.3% (106/215) for those older than 45 years. A wide range of proviral loads were measured for both asymptomatic and symptomatic participants with no difference within groups according to age or gender; however, median PVL was 1.34 log10 higher for symptomatic participants. The adult prevalence of HTLV-1 infection in central Australia is the highest reported worldwide. Sexual contact is likely to be the predominant mode of transmission.

Risk factors for HTLV-1 infection in Central Africa: A rural population-based survey in Gabon

BACKGROUND

Human T-Lymphotropic Virus type 1 (HTLV-1) is a human oncoretrovirus that infects at least 5 to 10 million people worldwide and is associated with severe diseases. Africa appears as the largest HTLV-1 endemic area. However, the risk factors for the acquisition of HTLV-1 remain poorly understood in Central Africa.

METHODS

We conducted an epidemiological survey between 2013 and 2017, in rural areas of 6 provinces of Gabon, in a rainforest environment. Epidemiological data were obtained and blood samples were collected after informed consent. Plasma were screened for HTLV-1 antibodies by ELISA and the positive samples were then tested by Western blot (WB). Genomic DNA derived from buffy-coat was subjected to two semi-nested PCRs amplifying either HTLV-1 env gene or LTR region fragments.

RESULTS

We recruited 2,060 individuals over 15 years old, including 1,205 men and 855 women (mean age: 49 years). Of these, 299 were found to be ELISA HTLV-1/2 seropositive. According to WB criteria, 136 were HTLV-1 (6.6%), 25 HTLV-1/2 (1.2%) and 9 HTLV seroreactive (0.4%). PCR results showed that 146 individuals were positive for at least one PCR: 104 for the env gene and 131 for the LTR region. Based on both serological and molecular results, 179 individuals were considered infected with HTLV-1, leading to an overall prevalence of 8.7%. The distribution of HTLV-1 infection was heterogeneous across the country. Based on multivariable analyses, female gender, increasing age, ethnicity (Pygmy) and multiple hospitalizations (more than 5 times) were found to be independent risk factors for HTLV-1 infection. Furthermore, a non-human primate bite appeared to be marginally associated with a higher risk of HTLV-1 infection.

CONCLUSION

Based on state-of-the-art serological and molecular methods, we have demonstrated that rural adult populations in Gabon are highly endemic for HTLV-1. Our results regarding risk factors should lead to public health actions aiming to reduce HTLV-1 transmission.

Serological detection of human T-cell lymphotropic virus types I and II among pregnant women in Ilorin, Nigeria

Human T-cell lymphotropic virus types I/II (HTLV-I/II) is endemic in some parts of the world including Nigeria. Reported prevalence rates in Nigeria have largely focused on blood donors. This study aims at determining the prevalence of HTLV infection among pregnant women in Ilorin North-central Nigeria. Serum samples from 276 pregnant women who were antenatal clinic attendees at General and Civil Service Hospitals in Ilorin were tested for the presence of HTLV-I/II antibodies using Enzyme Linked Immunosorbent Assay test kits from Diagnostic Automation INC., USA. Out of the 276 women tested, 3 tested positive giving a prevalence rate of 1.1%. The result was analyzed on the basis of age, marital status, nature of family, educational status, occupation, religion, parity, and gestational stage of the women. There was no statistical association of HTLV positivity with any of the variables. Although relatively lower than prevalence rate recorded among similar study groups in other parts of the country, the 1.1% prevalence in this study underscores the need for proper education and creation of awareness among antenatal clinic attendees, so as to reduce viral transmission and incidence of HTLV-related diseases.

Analysis of HTLV-1 proviral load (PVL) and antibody detected with various kinds of tests in Japanese blood donors to understand the relationship between PVL and antibody level and to gain insights toward better antibody testing

Adult T-cell leukemia/lymphoma (ATL) occurs in approximately 5% of individuals infected with human T-cell leukemia virus type 1 (HTLV-1). A high proviral load (PVL; more than four copies per 100 peripheral blood mononuclear cells (PBMCs) or 1.6 copies per 100 blood leukocytes) and being male are risk factors for ATL development. Whether anti-HTLV-1 antibody level is related to such risk is unknown. Here, PVL and antibody levels were examined using real-time PCR and other tests in 600 HTLV-1 positive screened Japanese blood donors to understand the relationship between PVL and antibody level in asymptomatic carriers and to gain insights toward better antibody testing for HTLV-1 infection. The 430 donors in whom proviral DNA was detected were considered as true positives for HTLV-1 infection. Among donors aged 40 years or older, more males than females had a PVL corresponding to more than 1.6% infected leukocytes, and an antibody titer below the median (P = 0.0018). In antibody tests using an HTLV-1 positive cell line or Env antigens there was a large discrepancy in antibody titer among 13 provirus-positive samples, probably suggesting that antibody-based screening tests should incorporate multiple HTLV-1 antigens, such as Gag and Env antigens.

The prevalence and clinical associations of HTLV-1 infection in a remote Indigenous community

OBJECTIVE

Hospital and laboratory data indicate that human T-lymphotropic virus type 1 (HTLV-1) is endemic to central Australia, but no community-based studies of its prevalence or disease burden have been reported. We determined the prevalence rates of HTLV-1 infection and of HTLV-1-associated diseases in a remote Indigenous community.

SETTING

A remote Northern Territory community.

DESIGN

All residents were asked to complete a health survey and offered a limited clinical examination, together with serological tests for HTLV-1 and Strongyloides, and HTLV-1 proviral load (PVL) assessment.

MAIN OUTCOME MEASURES

HTLV-1 seropositivity rates; HTLV-1 PVL (copies/105 peripheral blood leucocytes [PBL]); presentation with HTLV-1-related clinical disease.

RESULTS

HTLV-1 serostatus was determined for 97 of 138 residents (70%). The prevalence of HTLV-1 infection was significantly higher among adults (30 of 74 people tested) than children (1 of 23; P = 0.001). Nine of 30 HTLV-1-positive adults had a clinical syndrome that was potentially attributable to HTLV-1 infection (chronic lung disease, seven; symptomatic strongyloidiasis, two). The median HTLV-1 PVL was significantly higher for adults with chronic lung disease than for those who were asymptomatic (chronic lung disease, 649 copies/105 PBL [IQR, 162-2220]; asymptomatic adults, 40 copies/105 PBL [IQR, 0.9-229]; P = 0.017). Ten of 72 adults tested were seropositive for Strongyloides (six of 28 HTLV-1-positive participants and four of 44 HTLV-1-negative participants; P = 0.17), as were three of 15 children tested; the three children were HTLV-1-negative.

CONCLUSION

The prevalence of HTLV-1 infection and the rate of disease potentially attributable to HTLV-1 were high among adults in this remote community.

Human T-cell leukemia virus-associated malignancy

Human T-cell leukemia virus type 1 (HTLV-1) is a tumorigenic delta retrovirus and the causative infectious agent of a non-Hodgkin's peripheral T-cell malignancy called adult T-cell leukemia/lymphoma (ATL). ATL develops in approximately 5% of infected individuals after a significant clinical latency period of several decades. Clinical classifications of ATL include smoldering, chronic, lymphoma, and acute subtypes, with varying median survival ranges of a few months to several years. Depending on the ATL subtype and disease symptoms, treatment options include 'watchful waiting', chemotherapy, antiviral therapy, allogeneic hematopoietic stem cell transplantation (alloHSCT), and targeted therapies. Herein we review the characteristics and development of ATL, as well as current and future treatment options and perspectives.

Human T-Lymphotropic Virus type 1 infection in an Indigenous Australian population: epidemiological insights from a hospital-based cohort study

BACKGROUND

The Human T Lymphotropic Virus type 1 (HTLV-1) subtype C is endemic to central Australia where each of the major sequelae of HTLV-1 infection has been documented in the socially disadvantaged Indigenous population. Nevertheless, available epidemiological information relating to HTLV-1c infection is very limited, risk factors for transmission are unknown and no coordinated program has been implemented to reduce transmission among Indigenous Australians. Identifying risk factors for HTLV-1 infection is essential to direct strategies that could control HTLV-1 transmission.

METHODS

Risk factors for HTLV-1 infection were retrospectively determined for a cohort of Indigenous Australians who were tested for HTLV-1 at Alice Springs Hospital (ASH), 1st January 2000 to 30th June 2013. Demographic details were obtained from the ASH patient management database and the results of tests for sexually transmitted infections (STI) were obtained from the ASH pathology database.

RESULTS

Among 1889 Indigenous patients whose HTLV-1 serostatus was known, 635 (33.6 %) were HTLV-1 Western blot positive. Only one of 77 (1.3 %) children tested was HTLV-1 infected. Thereafter, rates progressively increased with age (15-29 years, 17.3 %; 30-49 years, 36.2 %; 50-64 years, 41.7 %) reaching 48.5 % among men aged 50-64 years. In a multivariable model, increasing age (OR, 1.04; 95 % CI, 1.03-1.04), male gender (OR, 1.41; 95 % CI, 1.08-1.85), residence in the south (OR, 10.7; 95 % CI, 7.4-15.6) or west (OR, 4.4; 95 % CI, 3.1-6.3) of central Australia and previous STI (OR, 1.42; 95 % CI, 1.04-1.95) were associated with HTLV-1 infection. Infection was acquired by three of 351 adults who were tested more than once during the study period (seroconversion rate, 0.24 (95 % CI = 0.18-2.48) per 100 person-years).

CONCLUSIONS

This study confirms that HTLV-1 is highly endemic to central Australia. Although childhood infection was documented, HTLV-1 infection in adults was closely associated with increasing age, male gender and STI history. Multiple modes of transmission are therefore likely to contribute to high rates of HTLV-1 infection in the Indigenous Australian population. Future strategies to control HTLV-1 transmission in this population require careful community engagement, cultural understanding and Indigenous leadership.

High prevalence of HTLV-1 infection among Japanese immigrants in non-endemic area of Brazil

Background

Human T-lymphotropic virus type 1 (HTLV-1) has worldwide distribution and is considered endemic in many world regions, including southwestern Japan and Brazil. Japanese immigrants and their descendants have a high risk of acquiring this infection due to intense population exchange between Brazil and Japan.

Objective

This cross-sectional study aimed to estimate the prevalence of HTLV, analyze the main risk factors associated with this infection, identify the main circulating types and subtypes of HTLV in Japanese immigrants and descendants living in Campo Grande-MS (Middle-West Brazil), as well as analyze the phylogenetic relationship among isolates of HTLV.

Study Design

A total of 219 individuals were interviewed and submitted to blood collection. All collected blood samples were submitted for detection of anti-HTLV-1/2 using the immunoassay ELISA and confirmed by immunoblot method. The proviral DNA of the 14 samples HTLV- 1 positive were genotyped by nucleotide sequencing.

Results

The overall prevalence of HTLV-1 was 6.8% (IC 95%: 3,5-10,2). Descriptive analysis of behavioral risk factors showed statistical association between HTLV-1 and age greater than or equal to 45 years. The proviral DNA of HTLV-1 was detected in all HTLV-1 positive samples. Of these, 14 were sequenced and classified as Cosmopolitan subtype, and 50% (7/14) belonged to subgroup A (transcontinental) and 50% (7/14) to the subgroup B (Japanese).

Conclusion

The high prevalence of HTLV-1 found evidence of the importance of early diagnosis and counseling of individuals infected with HTLV-1 for the control and prevention of the spread of this infection among Japanese immigrants and their descendants in Central Brazil.

The population of Okinawan immigrants is considered vulnerable to human T-lymphotropic virus type 1 (HTLV-1) infection because the Okinawa region in Japan is an endemic area. The second Brazilian largest Okinawan community is set in Campo Grande, Middle-West Brazil. This study aimed to estimate the prevalence and risk factors associated with HTLV infection among Japanese immigrants and their descendants living in Campo Grande. The prevalence of 6.8% of HTLV-1 infection that was found is considered high. The HTLV-1 infection was associated with age ranged from 45 years old or older. Most infected individuals are Okinawan descendants. The HTLV-1 rate found in the present study indicates that the prevalence of this infection remains high among this Japanese community. This study emphasizes the importance of implementing preventive and diagnostic public health policies to decrease the risk of HTLV-1 transmission among Japanese communities throughout Brazil.

Epidemiological Aspects and World Distribution of HTLV-1 Infection

The human T-cell leukemia virus type 1 (HTLV-1), identified as the first human oncogenic retrovirus 30 years ago, is not an ubiquitous virus. HTLV-1 is present throughout the world, with clusters of high endemicity located often nearby areas where the virus is nearly absent. The main HTLV-1 highly endemic regions are the Southwestern part of Japan, sub-Saharan Africa and South America, the Caribbean area, and foci in Middle East and Australo-Melanesia. The origin of this puzzling geographical or rather ethnic repartition is probably linked to a founder effect in some groups with the persistence of a high viral transmission rate. Despite different socio-economic and cultural environments, the HTLV-1 prevalence increases gradually with age, especially among women in all highly endemic areas. The three modes of HTLV-1 transmission are mother to child, sexual transmission, and transmission with contaminated blood products. Twenty years ago, de Thé and Bomford estimated the total number of HTLV-1 carriers to be 10-20 millions people. At that time, large regions had not been investigated, few population-based studies were available and the assays used for HTLV-1 serology were not enough specific. Despite the fact that there is still a lot of data lacking in large areas of the world and that most of the HTLV-1 studies concern only blood donors, pregnant women, or different selected patients or high-risk groups, we shall try based on the most recent data, to revisit the world distribution and the estimates of the number of HTLV-1 infected persons. Our best estimates range from 5-10 millions HTLV-1 infected individuals. However, these results were based on only approximately 1.5 billion of individuals originating from known HTLV-1 endemic areas with reliable available epidemiological data. Correct estimates in other highly populated regions, such as China, India, the Maghreb, and East Africa, is currently not possible, thus, the current number of HTLV-1 carriers is very probably much higher.

Clinical pathophysiology of human T-lymphotropic virus-type 1-associated myelopathy/tropical spastic paraparesis

Human T-lymphotropic virus type 1 (HTLV-1), a human retrovirus, is the causative agent of a progressive neurological disease termed HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP). HAM/TSP is a chronic inflammatory disease of the central nervous system and is characterized by unremitting myelopathic symptoms such as spastic paraparesis, lower limb sensory disturbance, and bladder/bowel dysfunction. Approximately 0.25-3.8% of HTLV-1-infected individuals develop HAM/TSP, which is more common in women than in men. Since the discovery of HAM/TSP, significant advances have been made with respect to elucidating the virological, molecular, and immunopathological mechanisms underlying this disease. These findings suggest that spinal cord invasion by HTLV-1-infected T cells triggers a strong virus-specific immune response and increases proinflammatory cytokine and chemokine production, leading to chronic lymphocytic inflammation and tissue damage in spinal cord lesions. However, little progress has been made in the development of an optimal treatment for HAM/TSP, more specifically in the identification of biomarkers for predicting disease progression and of molecular targets for novel therapeutic strategies targeting the underlying pathological mechanisms. This review summarizes current clinical and pathophysiological knowledge on HAM/TSP and discusses future focus areas for research on this disease.

Blocking vertical transmission of human T cell lymphotropic virus type 1 and 2 through breastfeeding interruption

BACKGROUND

Human T cell lymphotropic virus type 1 and 2 (HTLV-1/2) causes serious diseases and is endemic in many parts of the world. It is transmitted from mother to child in 15-25% of the cases, primarily through breastfeeding. Proviral load and duration of breastfeeding are thought to play a role in transmission. This study aimed to detect HTLV-seropositive mothers through testing of neonates, to evaluate maternal HTLV proviral load and to measure the rates of transmission blocking when interruption of breastfeeding was implemented.

METHODS

Neonates were screened for HTLV-1/2 IgG by enzyme immunoassay using the neonatal screening program of Minas Gerais State, Brazil. Breastfeeding interruption was recommended to those whose mothers were confirmed HTLV-positive. Children were tested by polymerase chain reaction at birth and at 12 months of age.

RESULTS

Of 55,293 neonates tested, 42 (0.076%) were positive for HTLV-1 or HTLV-2 IgG. All 42 were polymerase chain reaction-negative at birth and 1 of 37 (2.7%) became antibody-positive after 12 months. His mother had delivered him vaginally and was informed of the positive HTLV-1 polymerase chain reaction after 7 days of breastfeeding. The mother's proviral load was 271 copies/10,000 cells, whereas the average is 109.2 copies/10,000 cells (95% confidence interval: 70.56-147.83).

CONCLUSIONS

Maternal HTLV-1 proviral load and the route of delivery may have played a role in the transmission observed. Avoidance of breastfeeding was an effective measure to reduce HTLV transmission. In endemic countries, routine prenatal or neonatal screening combined with formula feeding for mothers confirmed HTLV-positive may be an important strategy to prevent future development of illnesses related to HTLV.

Short communication: human lymphotropic virus type 1 coinfection modulates the synthesis of cytokines by peripheral blood mononuclear cells from HIV type 1-infected individuals

HIV-1 and HTLV-1 infect CD4(+) T lymphocyte but little is known about the impact of coinfection on patient's immune response. In this study we have evaluated the spontaneous production of interleukin (IL)-2, IL-4, IL-6, and IL-10 and interferon (IFN)-γ by unstimulated peripheral blood mononuclear cell (PBMC) cultures obtained from patients infected by HTLV-1, HIV-1, or both viruses. We have observed that HIV/HTLV-coinfected individuals presented significantly higher production of IL-2 and IFN-γ compared to both HIV single-infected and HTLV single-infected individuals. IL-6 and IL-10 synthesis was similar in all infected groups, but HTLV single-infected individuals presented a lower production of IL-4. These results show that HIV/HTLV-coinfected individuals presented a profile of higher production of Th-1 cytokines, suggesting a predominant stimulus of HTLV-1 in detriment to HIV-1 infection.

Current status of HTLV-1 infection

It is 30 years since human T-cell leukemia virus type 1 (HTLV-1) was identified as the first human retrovirus. To assess the implications of the virus for human health it is very important to know the past and present prevalence. Most of the estimates of HTLV-1 prevalence are based on serological screening of blood donors, pregnant women and other selected population groups. The widely cited estimate that the number of HTLV-1 carriers in Japan is 1.2 million was calculated from data that are now more than 25 years old. Here I summarize previous reports of prevalence studies in the world and Japan. Then, a recent analysis of seroprevalence of healthy blood donors in Japan will be described in comparison with that of 1988. A decrease in the number of HTLV-1 carriers in Japan was demonstrated, however, it is still more than one million. The number has increased in the metropolitan areas, probably reflecting the migration of Japanese population. I conclude that there is a paucity of general population data in countries where HTLV-1 is endemic, and re-evaluation of HTLV-1 infection is required to understand the virus burden on the human health.

Differential distribution of antibodies to different viruses in young animals in the free-ranging rhesus macaques of Cayo Santiago

BACKGROUND

The breeding colony of free-ranging rhesus macaques was established in 1938 in Cayo Santiago (CS) with animals collected in northern India. The seroprevalence to cercopithecine herpesvirus type 1 (B virus) and simian retroviruses has been studied previously.

RESULTS

This is the first report on the seropositivity to different viruses using samples collected shortly after removing animals (n = 245) from CS. All samples were negative for measles, simian immunodeficiency virus and simian type D retroviruses. The overall prevalence of antibodies was around 50% for simian T-lymphotropic virus I (STLV-I). For B virus, the prevalence was 38%.

CONCLUSIONS

Data obtained showed marked differences in the antibody distribution to B virus and STLV-I within the free-ranging colony of rhesus macaques. Implication of these data for the Specific Pathogen Free program at the Caribbean Primate Research Center are also discussed.

Infectious Agents

There is substantial evidence that infectious agents play a causal role in a variety of human malignancies. These cancers include the liver, cervix, stomach, nasopharynx, bladder, and bile duct as well as Kaposi sarcoma (KS) and several lymphomas. This chapter summarizes the biological and epidemiologic features of each of the major oncogenic infections, beginning with the viruses, followed by H. pylori, and with a brief summary of the relevant parasites.

Human T-lymphotropic virus type 1 (HTLV-1) prevalence and quantitative detection of DNA proviral load in individuals with indeterminate/positive serological results

BACKGROUND

HTLV-1 infection is currently restricted to endemic areas. To define the prevalence of HTLV-1 infection in patients living in Italy, we first carried out a retrospective serological analysis in a group of people originating from African countries referred to our hospital from January 2003 to February 2005. We subsequently applied a real time PCR on peripheral blood mononuclear cells from subjects with positive or indeterminate serological results.

METHODS

All the sera were first analysed by serological methods (ELISA and/or Western Blotting) and then the peripheral blood mononuclear cells from subjects with positive or inconclusive serological results were analyzed for the presence of proviral DNA by a sensitive SYBR Green real time PCR. In addition, twenty HTLV-I ELISA negative samples were assayed by real time PCR approach as negative controls.

RESULTS

Serological results disclosed serum reactivity by ELISA (absorbance values equal or greater than the cut-off value) in 9 out of 3408 individuals attending the Sexually Transmitted Diseases Clinic and/or Oncology Department, and 2 out 534 blood donors enrolled as a control population. Irrespective of positive or inconclusive serological results, all these subjects were analyzed for the presence of proviral DNA in peripheral blood mononuclear cells by SYBR real time PCR. A clear-cut positive result for the presence of HTLV-1 DNA was obtained in two subjects from endemic areas.

CONCLUSION

SYBR real time PCR cut short inconclusive serological results. This rapid and inexpensive assay showed an excellent linear dynamic range, specificity and reproducibility readily revealing and quantifying the presence of virus in PBMCs. Our results highlight the need to monitor the presence of HTLV-1 in countries which have seen a large influx of immigrants in recent years. Epidemiological surveillance and correct diagnosis are recommended to verify the prevalence and incidence of a new undesirable phenomenon.

Expression of glucose transporter 1 confers susceptibility to human T-cell leukemia virus envelope-mediated fusion

Human T-cell leukemia virus type 1 (HTLV-1) was the first human retrovirus identified and causes both adult T-cell leukemia/lymphoma and tropical spastic paraparesis/HTLV-1-associated myelopathy, among other disorders. In vitro, HTLV-1 has an extremely broad host cell tropism in that it is capable of infecting most mammalian cell types, although at the same time viral titers remain relatively low. Despite years of study, only recently has a bona fide candidate cellular receptor, glucose transporter 1 (glut-1), been identified. Although glut-1 was shown to bind specifically to the ectodomain of HTLV-1 and HTLV-2 envelope glycoproteins, which was reversible with small interfering RNA directed against glut-1, cellular susceptibility to HTLV upon expression of glut-1 was not established. Here we show that expression of glut-1 in relatively resistant MDBK cells conferred increased susceptibility to both HTLV-1- and HTLV-2-pseudotyped particles. glut-1 also markedly increased syncytium formation in MDBK cells after exposure to HTLV-1. Another assay also demonstrated HTLV-1 envelope-cell fusion in the presence of glut-1. Taken together, these results provide additional evidence that glut-1 is a receptor for HTLV.

Current views in HTLV-I-associated adult T-cell leukemia/lymphoma

Epidemiological studies have demonstrated that the relative percentage of malignant lymphoid proliferations varies widely according to geographical location and ethnic populations. HTLV-I is the etiological agent of adult T-cell leukemia/lymphoma (ATLL) and is also associated with cutaneous T-cell lymphoma (CTCL). However, a definite role of HTLV-I in mycosis fungoides (MF) and/or Sezary syndrome (SS) remains controversial. While most HTLV-I-infected individuals remain asymptomatic carriers, 1-5% will develop ATLL, an invariably fatal expansion of virus-infected CD4+ T cells. This low incidence and the long latency period preceding occurrence of the disease suggest that additional factors are involved in development of ATLL. In this review, diagnosis, clinical features, and molecular pathogenesis of HTLV-I are discussed.

Non-invasive testing reveals a high prevalence of simian T-lymphotropic virus type 1 antibodies in wild adult chimpanzees of the Taï National Park, Côte d'Ivoire

Little information is available on the prevalence of retrovirus infections in populations of non-human primates living in their natural habitats. To gain such information, methods were developed to detect antibodies to simian T-lymphotropic virus type 1 (STLV-1) in urine from wild chimpanzees. Samples from more than 74 chimpanzees living in three communities in the Taï National Park, Côte d'Ivoire, were analysed. The prevalence of STLV-1 antibodies in adults and adolescents was significantly higher (35/49, 71·4 %) than that in infant and juvenile chimpanzees (3/31, 9·7 %).

Methylenetetrahydrofolate reductase genotype does not play a role in adult T-cell leukemia/lymphoma pathogenesis among human T-lymphotrophic virus type 1 carriers

Human T-lymphotropic virus type 1 (HTLV-1) is associated with adult T-cell leukemia/lymphoma (ATL). However, the incidence of ATL is low among HTLV-1 carriers suggesting additional mechanisms are involved in the progression of the disease. A recent study found that polymorphisms in the methylenetetrahydrofolate reductase (MTHFR) gene influence the susceptibility to malignant lymphoma. We have analyzed the MTHFR genotype in 81 HTLV-1 carriers and 87 ATL patients. No statistically significant associations were found between MTHFR genotype and development of ATL. These data suggest that genetic polymorphisms in the MTHFR locus do not play a role in ATL pathogenesis among HTLV-1 carriers.

Neurological manifestations in HTLV-I-infected blood donors

The human T-cell lymphotropic virus type 1 (HTLV-I) causes a neurological disease known as HTLV-I-associated myelopathy/tropical spastic paraparesis (HAM/TSP) in a minority of infected individuals. Although other neurological outcomes have been described their prevalence is presently unknown. To evaluate the frequency and characteristics of neurological involvement in a population of HTLV-I-infected blood donors we investigated 196 HTLV-I positive and 196 negative blood donors from a blood center of Rio de Janeiro, Brazil. Individuals with abnormalities at the neurological examination were examined by three neurologists, and when pertinent, additional neurological investigations were performed. Descriptive analysis, Student's t-test and chi2 test were employed for statistical analysis. Neurological abnormalities were found in 71 (36.2%) of the HTLV-I positive blood donors and in only 29 (14.8%) of the HTLV-I negative donors (OR = 2.54, 95% CI = 1.67-3.59, p = 0.000002). Cases of myelopathy, motor neuron disease and myopathy were only found in the HTLV-I positive group. In addition, peripheral neuropathy (PN) was significantly more frequent in the positive group (p = 0.015). In summary, our data suggest that HTLV-I-infected individuals exhibit a wide variety of neurological manifestations apart from the classical picture of HAM/TSP.

Genetic instability of adult T-cell leukemia/lymphoma by comparative genomic hybridization analysis

Adult T-cell leukemia/lymphoma (ATL) is a distinct clinicopathological entity, i.e., peripheral T-lymphocytic malignancy caused by human T-lymphotropic virus type I (HTLV-1) with diverse clinical features. High frequency of genetic instability (GIN) in both aggressive and indolent ATL was detected by comparative genomic hybridization (CGH). Among GIN, chromosomal instability, i.e., ancuploidy, in indolent ATL was as frequent but less complex and dynamic as compared to those in aggressive ATL. Some of the CGH alterations, including gain of 14q32, appear to be rather ATL specific. Clonal instability of HTLV-1-infected T cells. i.e., emergence of distinct clone, was detected in about one forth of acute crisis from indolent ATL by CGH and Southern blotting for HTLV-1. Taking together with the previous reports of frequent subtle mutations in several tumor suppressor genes in aggressive ATL, GIN in multistep leukemogenesis of ATL is diverse including clonal, chromosomal, and nucleotide levels.

Spatial distribution of the Human T-Lymphotropic Virus types I and II (HTLV-I/II) infection among blood donors of Hemominas Foundation, Belo Horizonte, Minas Gerais State, Brazil, 1994-1996

We conducted a cross-sectional study of the spatial distribution of HTLV-I/II infection among blood donors of Hemominas Foundation, living in Belo Horizonte, from 1994 to 1996. Study population (1,022) was composed by 533 cases (positive Western Blot (WB), indeterminate WB and ELISA positive without WB result) and a random sample of 489 non-cases (HTLV-I/II serum negative). Cases and non-cases were georeferenced using the exact or an approximation of the household address reported at the blood donation interview. Using multivariate analysis, cases with WB result are less likely to be reposition blood donors compared to voluntary ones (OR = 0.70; CI 95%: 0.50-0.99). Using the difference between univariate K functions, we found no evidence that cases and non-cases differ in their spatial distribution. We found no evidence that cases with and without WB result differ in the distance between their residence and Hemominas Foundation. No donors without WB result were georeferenced by the exact address. These donors could not have received the Hemominas letter inviting them to return to collect the second blood sample.

Comparative genomic hybridization analysis in adult T-cell leukemia/lymphoma: correlation with clinical course

Sixty-four patients with adult T-cell leukemia/lymphoma (ATL; 18 patients with indolent subtype and 46 with aggressive subtype) associated with human T-lymphotropic virus type 1 (HTLV-1) were analyzed using comparative genomic hybridization (CGH). The most frequent observations were gains at chromosomes 14q, 7q, and 3p and losses at chromosomes 6q and 13q. Chromosome imbalances, losses, and gains were more frequently observed in aggressive ATL than in indolent ATL, with significant differences between the 2 ATL subtypes at gains of 1q and 4q. An increased number of chromosomal imbalances was associated with a significantly shorter survival in all patients. A high number of chromosomal losses was associated with a poor prognosis in indolent ATL, whereas the presence of 7q+ was marginally associated with a good prognosis in aggressive ATL. Paired samples (ie, samples obtained at different sites from 4 patients) and sequential samples from 13 patients (from 6 during both chronic disease and acute crisis and from 7 during both acute onset and relapse) were examined by CGH and Southern blotting for HTLV-1. All but 2 paired samples showed differences on CGH assessment. Two chronic/crisis samples showed distinct results regarding both CGH and HTLV-1 integration sites, indicating clonal changes in ATL at crisis. In 11 patients, the finding of identical HTLV-1 sites and clonally related CGH results suggested a common origin of sequential samples. In contrast to chronic/crisis samples, CGH results with all acute/relapse sample pairs showed the presence of clonally related but not evolutional subclones at relapse, thereby suggesting marked chromosomal instability. In summary, clonal diversity is common during progression of ATL, and CGH alterations are associated with clinical course. (Blood. 2001;97:3875-3881)

Incidence of hematological malignancies in Martinique, French West Indies, overrepresentation of multiple myeloma and adult T cell leukemia/lymphoma

A registry of hematological malignancies is held in the unit of cytology of the University Hospital of Martinique. Human T cell lymphotropic virus type-1 (HTLV1) is endemic in this island. We determined the incidence and epidemiological features of hematological malignancies from the 715 new cases diagnosed between 1990 and 1998 among the adult population. Incidence rates per year were steady during this period. The most frequent hematological malignancies were multiple myeloma (MM) (34%), followed by non-Hodgkin's lymphoma (NHL) (23%). Among the cases of NHL with an immunohistological study, 57% had a T cell phenotype. Among these 61% were adult T cell leukemia/lymphoma. Epidemiological data on hematological malignancies in the West Indies has not been previously reported. There are two striking differences with other population-based registries: a high incidence of MM (5/100000) and a high proportion of T cell NHL among NHL (57%). The high proportion of T cell NHL is probably due to the high incidence of ATL. A low incidence of B cell NHL might also contribute to this effect. The increased incidence of MM in West Indies had not been previously reported. A similar high incidence of MM has been reported among Afro-Americans in the USA.

Human T-lymphotropic virus type I provirus and T-cell prolymphocytic leukemia

T-cell prolymphocytic leukemia (T-PLL) is a rare type of post-thymic T-cell neoplasm, the etiology of which is unknown. Patients with T-PLL have been found to be seronegative for human T-lymphotropic virus type-I (HTLV-I), and their leukemia cells do not retain monoclonally integrated HTLV-I provirus. Recently, we have demonstrated the presence of defective HTLV-I provirus by polymerase chain reaction in the DNA extracted from peripheral blood cells or affected lymph nodes of T-PLL patients. Although there is a possibility, from our observation, that an alternative mechanism is operating in HTLV-associated leukemogenesis, it is still unknown whether and how HTLV-I can contribute to the leukemogenesis of T-PLL. In this review, we describe controversial issues and discuss a role of HTLV-I in the leukemogenesis of T-PLL.

Human T-lymphotropic virus type 1 infection

Human T-cell lymphotropic virus type-1 (HTLV-1) is aetiologically associated with adult T-cell leukaemia/lymphoma (ATL). HTLV-1 infection can also lead to various non-malignant diseases, for example, HTLV-1 associated myelopathy/tropical spastic paraparesis and HTLV-1 uveitis. HTLV-1 is endemic in southern Japan and the Caribbean. HTLV-1 infection is mainly transmitted by either breast-feeding, sexual intercourse or blood transfusions. Primary prevention of HTLV-1 in endemic areas by screening of blood and by refraining from breast-feeding have been successful. The incidence of ATL is rather low among HTLV-1 carriers (<5%). The precise mechanism of development of ATL remains unknown. It is a multiple-step process which does not require viral expression in the later stages of leukaemogenesis. Many samples have mutations of the tumour suppressor genes, p53 and/or p16(INK4A). Four subtypes of ATL have been identified, each having distinctive clinical features. Monoclonal integration of HTLV-1 proviral DNA into tumour cells is found in each of the subtypes. At present, no effective therapy for ATL exists.

Evaluation of adult T-cell leukemia/lymphoma incidence and its impact on non-Hodgkin lymphoma incidence in southwestern Japan

The incidence of adult T-cell leukemia/lymphoma (ATL) and its impact on that of total non-Hodgkin lymphoma (NHL) were evaluated in Nagasaki, an area in southwestern Japan where human T-cell lymphotropic virus type I (HTLV-I) is endemic. The first study area comprised 4 towns located on the K Islands, which had a population of 26,870 in 1990. The overall HTLV-I seroprevalence estimated from the serologic survey of 18,485 subjects was 16.2%. By using the data from the Nagasaki Prefectural Cancer Registry (NPCR) and reviewing clinical and laboratory information, we identified 40 cases of ATL and 35 cases of other NHL diagnosed between 1985 and 1995. The crude annual incidence of ATL among 100,000 HTLV-I carriers aged 30 or older was estimated at 137.7 for men and 57.4 for women, with a significant sex difference after adjustment for age (rate ratio = 2.50, 95% confidence interval 1.32-4.73). The cumulative risk from 30 to 79 years of age was estimated at approximately 6.6% for men and 2.1% for women. Among the entire population, ATL accounted for 51 to 59% of the total NHL incidence, showing the strong impact of HTLV-I infection. The second study area comprised the whole of Nagasaki Prefecture (total population in 1990 = 1.56 million). Between 1985 and 1995, 989 cases of ATL and 1,745 cases of other NHL were registered in the NPCR. The world age-standardized annual incidence rate of ATL per 100,000 persons aged 30 or older was estimated at 10.5 for men and 6.0 for women, which accounted for approximately 37 to 41% of the total NHL incidence.

Human T-lymphotropic virus type I among blood donors from Guadeloupe: donation, demographic, and biologic characteristics

BACKGROUND

Epidemiologic data on human T-lymphotropic virus type I (HTLV-I) in Guadeloupe (French West Indies) are scant.

STUDY DESIGN AND METHODS

From January 1989 to December 1996, 59,426 blood donors were screened by enzyme immunoassay for antibodies to HTLV-I. All repeatedly reactive samples were confirmed by Western blot. Temporal trends in HTLV-I seropositivity rates were examined during the study period. A multivariate analysis of donation, demographic, and biologic characteristics was performed.

RESULTS

Of the screened blood donors, 195 were confirmed as seropositive, for an overall prevalence of 0.33 percent (95% CI 0.28-0.38). A marked decrease in overall HTLV-I prevalence with time (from 0.47% in 1989 to 0.13% in 1996) was observed, which can be explained mainly by the decreasing percentage of recruited new donors during the study period. Four independent risk factors for HTLV-I were identified: new donor status (odds ratio [OR] 12.5), female sex (OR 1.7), increasing age (30-39 years: OR, 2.4; 40-49 years: OR, 3.7; >50 years: OR 6.6), and positive antibodies to hepatitis B virus core antigen (OR, 1.7). Selection of specific locations for blood collection was inversely associated with HTLV-I (OR 0.5).

CONCLUSION

New donor status, advancing age, female sex, and positivity for hepatitis B virus core antibodies were the major factors associated with HTLV-I infection in Guadeloupe.

Community-based molecular epidemiology of HTLV type I in Taiwan and Kinmen: implication of the origin of the cosmopolitan subtype in northeast Asia

To understand the possible origin and dissemination of HTLV-I infection in northeast Asia, community-based molecular epidemiological studies were conducted on the Kinmen Islands (off the coast of Fukien Province, China) and in Taiwan. A total of 3831 Taiwanese from 3 townships (Pu-Li, Chu-Dung, and Pu-Tze) and 993 aborigines from 4 tribes in Taiwan participated in this study. The prevalence rates of HTLV-I infection in adult residents from Pu-Li, Chu-Dung, and Pu-Tze were 0.82, 1.72, and 1.63%, respectively. None of the aborigines had HTLV-I infection. Previously, 0.73% of the adult population of Kin-Hu, Kinmen were found to have HTLV-I infection. Peripheral blood mononuclear cells were collected from HTLV-I carriers identified both in Taiwan and Kinmen and the HTLV-I LTR sequences were PCR amplified, subcloned, and sequenced for phylogenetic tree analysis. The results showed that all 6 HTLV-I isolates from Kinmen and 13 of 18 (72.2%) isolates from Taiwan were group a (transcontinental) of Cosmopolitan subtype, while 5 of 18 (27.8%) isolates from Taiwan were group b (Japanese) of Cosmopolitan subtype. Since all of the HTLV-I-infected persons were descendants of immigrants from mainland China, the origin of the Cosmopolitan subtype in Taiwan and Kinmen may not have been Japan, as previously theorized, but China, possibly the result of the migration of an infected population in the past several centuries.

Human T-lymphotropic virus type-I infection, antibody titers and cause-specific mortality among atomic-bomb survivors

There have been few longitudinal studies on the long-term health effects of human T-lymphotropic virus type-I (HTLV-I) infection. The authors performed a cohort study of HTLV-I infection and cause-specific mortality in 3,090 atomic-bomb survivors in Nagasaki, Japan, who were followed from 1985-1987 to 1995. The prevalence of HTLV-I seropositivity in men and women was 99/1,196 (8.3%) and 171/1,894 (9.0%), respectively. During a median follow-up of 8.9 years, 448 deaths occurred. There was one nonfatal case of adult T-cell leukemia/lymphoma (incidence rate = 0.46 cases/1,000 person-years; 95% confidence interval [CI] 0.01-2.6). After adjustment for sex, age and other potential confounders, significantly increased risk among HTLV-I carriers was observed for deaths from all causes (rate ratio [RR] = 1.41), all cancers (RR = 1.64), liver cancer (RR = 3.04), and heart diseases (RR = 2.22). The association of anti-HTLV-I seropositivity with mortality from all non-neoplastic diseases (RR = 1.40) and chronic liver diseases (RR = 5.03) was of borderline significance. Possible confounding by blood transfusions and hepatitis C/B (HCV/HBV) viral infections could not be precluded in this study. However, even after liver cancer and chronic liver diseases were excluded, mortality rate was still increased among HTLV-I carriers (RR = 1.32, 95% CI 0.99-1.78), especially among those with high antibody titers (RR = 1.56, 95% CI 0.99-2.46, P for trend = 0.04). These findings may support the idea that HTLV-I infection exerts adverse effects on mortality from causes other than adult T-cell leukemia/lymphoma. Further studies on confounding by HCV/HBV infections and the interaction between HCV/HBV and HTLV-I may be required to analyze the increased mortality from liver cancer and chronic liver diseases.

Clonal integration and expression of human T-cell lymphotropic virus type I in carriers detected by polymerase chain reaction and inverse PCR

Adult T-cell leukemia (ATL) is a neoplasm of mature helper (CD4) T lymphocytes, and human T-cell lymphotropic virus type-I (HTLV-I) has been suggested to be the causative virus of ATL. HTLV-I integrates its proviruses into random sites in host chromosomal DNA. Clonal integration has been observed in patients with ATL, including smoldering, chronic, and acute states. However, random and/or polyclonal integration has only been reported in a few asymptomatic HTLV-I carriers. To clarify the clonality of HTLV-I-infected cells in carriers, we used an inverse polymerase chain reaction (IPCR), which is more sensitive than Southern blot analysis. We used the peripheral blood momonuclear cells (PBMC) from 16 asymptomatic carriers and the separated CD4-positive cells. No cases showed either a monoclonal or polyclonal integration of the HTLV-I provirus by Southern blot. But, using IPCR, 7 of 16 cases showed either mono- or oligoclonal integration. In addition, the populations of clonal provirus in the total PBMC were frequently different from those in the CD4-positive cells. Three cases showed expression of HTLV-I tax/rex mRNA in the total PBMC, but no such expression was found in CD4-positive cells. In this study, an unexpected frequency of clonal HTLV-I provirus DNA was observed in HTLV-I carriers. These findings indicate that the clonal but nonmalignant proliferation of HTLV-I-infected cells already occurs even in HTLV-I carriers, and therefore that some other step is necessary to induce malignant proliferation.

Integration Patterns of HTLV-I Provirus in Relation to the Clinical Course of ATL: Frequent Clonal Change at Crisis From Indolent Disease

We examined human T-lymphotropic virus type I (HTLV-I) DNA integration in 68 patients with adult T-cell leukemia/lymphoma (ATL) by Southern blotting using EcoRI, which does not cut within the 9 kb of the genome and probes for pX and gag-pol region of HTLV-I. We detected defective proviral integration as a monoclonal band of various sizes with the pX but not with the gag-pol probe, or a monoclonal band of less than 9 kb with the pX probe, in 20 patients (29.4%). These were designated defective (D) type. With both probes, a single band greater than 9 kb was detected in 34 (50.0%), designated complete (C) type, and two or more bands greater than 9 kb, were designated multiple (M) type, in 14 (20.6%). Advanced age, a high LDH value, and hypercalcemia were more frequent in D type patients. The median survival time (MST) was 6.8, 24.4, and 33.3 months, for D, C, and M types, respectively (log rank P = .006). Among 52 sequentially examined patients, the HTLV-I integration patterns changed in 4 (7.5%). In three of these four, the rearrangements of the T-cell receptor (TCR)b gene concomitantly changed, suggesting the appearance of a new ATL clone. Another patient had the same rearrangement of the TCRb gene, indicating clonal evolution. The HTLV-I integration pattern changed at crisis from indolent to aggressive ATL in three patients. These findings suggested that the HTLV-I integration patterns have clinical implications in ATL pathophysiology. In contrast to the clonal evolution characteristic of the multistep carcinogenesis of most human malignancies, the frequent clonal change of ATL at crisis is a peculiar phenomenon, probably reflecting the emergence of multiple premalignant clones in viral leukemogenesis as suggested in Epstein-Barr virus associated lymphomagenesis in the immunocompromised host.

Occurrence and frequency of transmission of naturally occurring simian retroviral infections (SIV, STLV, and SRV) at the CIRMF Primate Center, Gabon

Among the primates held at the CIRMF Primate Center, Gabon, no serological sign of SIV infection could be demonstrated in 68 cynomolgus monkeys, 60 chimpanzees, nine gorillas, and 12 sun-tailed monkeys, while seven of 102 mandrills and six of 24 vervets were infected with SIV. Six mandrills, seven vervets and ten cynomolgus monkeys exhibited a full HTLV type 1 Western blot profile. The sera of two gorillas and one chimpanzee presented with a positive but not typical HTLV Western blot profile. The sera of the gorillas lacked p24 antibodies, and the chimpanzee had a Western blot profile evocative of HTLV-II. All attempts to amplify viruses from these animals by PCR were unsuccessful. Two other chimpanzees and seven gorillas presented with indeterminate HTLV Western blot profiles. In the mandrill colony, only male animals were STLV seropositive and no sexual transmission to females was observed. SIV infection was also more frequent in male than female mandrills and sexual transmission appeared to be a rare event. No SRV infection was observed in macaques.

Mother-to-child transmission of human T-cell lymphotropic virus types I and II (HTLV-I/II) in Gabon: a prospective follow-up of 4 years

SUMMARY

For 4 years. we determined the mode and risk of mother-to-child transmission of HTLV-I in a prospective cohort of 34 children born to seropositive mothers in Franceville, Gabon. We also determined the prevalence of antibodies to HTLV-I/II in siblings born to seropositive mothers. Antibodies to HTLV-I/II were detected by Western blot, and the proviral DNA was detected by the polymerase chain reaction (PCR). The risk of seroconversion to anti-HTLV-I for the 4 years of follow-up was 17.5 percent. Anti-HTLV-I/II and proviral DNA were only detected after age 18 months. We observed a seroprevalence rate of 15 percent among the siblings born to HTLV-I/II seropositive mothers. Furthermore, we report a case of mother-to-child transmission of HTLV-II infection in a population of HTLV-II-infected pregnant women that is emerging in Gabon. The lack of detection of HTLV-I/II proviral DNA in cord blood and amniotic fluid and, furthermore, the late seroconversion observed in the children indirectly indicate that mother-to-child transmission occurred postnatally, probably through breast milk.

A population-based epidemiological study of human T-cell leukemia virus type I infection in Kin-Hu, Kinmen

Kinmen is a group of small islands located between Taiwan and Fu-Kien Province of mainland China. The general population in Kinmen are descendants of immigrants from mainland China who began arriving around 317 A.D. Since it has been reported that 0.48% of adults in Taiwan have HTLV-I infection, the decision was made to conduct a community-based epidemiological study in Kinmen to understand the origin and dissemination of HTLV-I in north-east Asia. Over 68% of residents of Kin-Hu township in Kinmen over 30 years of age participated in this study. Eight of 1,425 males and 14 of 1,595 females had HTLV-I infection. Antibody reactivities were further tested by Western blot assays with HTLV-I or HTLV-II type-specific recombinant envelope glycoproteins, and it was determined that all of those infected had HTLV-I and none had HTLV-II. Logistic regression was used for multivariate analysis. The final model indicated that the significant factors associated with HTLV-I infection in Kinmen were age and coastal residency. Age was positively correlated with HTLV-I infection. The eastern coastal area had a rate of HTLV-I infection 3.1 times higher than other areas in Kin-Hu. Further genetic analysis in Kinmen is needed to elucidate a relationship with other HTLV-I isolates in the world.

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.

Molecular detection of pre-ATL state among healthy HTLV-1 carriers in an endemic area of Japan

Adult T-cell leukemia/lymphoma (ATL) usually develops after age 40 in Japan, suggesting a long latency since HTLV-I is considered to be transmitted mainly from mothers to babies via breast milk. Our previous studies had suggested that HTLV-I carriers who have a monoclonal integration of HTLV-I proviral DNA in the peripheral blood cells, designated pre-ATL, account for about 2% of healthy carriers and are at high risk of developing ATL. Their ages ranged from 32 to 80 (median 57). Nevertheless, many cases of pre-ATL showed a long-lasting carrier state (10-year probability around 90%). In the present investigation we conducted a large-scale molecular detection of monoclonal integration in a population (481 cases) of healthy carriers with ages ranging from 16 to 82 (median 49) for the purpose of clarifying the earliest onset of this pre-ATL state. Southern-blot analysis of DNA extracted from peripheral blood mononuclear cells revealed 6 cases (1.2%) with a monoclonal band. All of these 6 were older than 40; no single positive case was found in 220 carriers under age 40. These results indicate that the molecularly detectable pre-ATL state also develops after a long latency. Thus the pre-ATL state seems to be a subtype of ATL showing an extremely indolent course of disease development, but not merely an early phase of all subtypes of ATL. We propose that, in order to reveal a promoter(s) responsible for the development of ATL from the pre-ATL state, intensive epidemiological investigation of life style, eating habits, occupation and exposure to carcinogens must be conducted on this unique group prone to ATL. It is also important to perform such an epidemiological study on the general population of carriers by paying special attention to the first 3-4 decades of each carrier's life in Japan and by comparing the data with those from carriers in different geographical areas of the world.

Mortality among inhabitants of an HTLV-I endemic area in Japan

A community-based cohort study was conducted to clarify the risk of human T-cell leukemia virus type I (HTLV-I) infection for cause-specific deaths. A total of 1,997 individuals (751 men and 1,246 women) aged 30 or older in A-Island, Nagasaki Prefecture, Japan who had voluntarily attended annual mass health examinations, including serum HTLV-I antibody test, were followed up for a mean period of 5.3 years. In a Cox proportional hazards analysis adjusted for age at baseline, the HTLV-I seropositivity was found to be associated with mortality from all causes in men (hazard ratio (HR) 1.89; 95% confidence interval (CI) 1.01-3.54) and women (HR 1.94; 95% CI 1.16-3.22). When the effects of 2 deaths (1 man and 1 woman) from adult T-cell leukemia/lymphoma (ATL) were excluded, the mortality risk decreased slightly but was still significantly or marginally significantly greater than 1 in both men (HR 1.77; 95% CI 0.93-3.37) and women (HR 1.87; 95% CI 1.12-3.12). Further analysis of cause-specific deaths revealed a significant increase in the risk for non-neoplastic diseases but not for neoplasms excluding ATL. These findings suggest that long-term HTLV-I infection represents a health hazard greater than just that for the development of ATL. It was difficult, however, to draw a conclusion regarding the association between HTLV-I infection and cancer risk, because the number of cancer deaths was small and the incidence of cancer was not investigated.

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.

Adult T cell leukaemia-lymphoma

Adult T cell leukaemia-lymphoma (ATL) was first discovered and reported in Japan, where it has a high incidence in the south-west region. The first human retrovirus HTLV-I (human T-cell lymphotropic virus type I) is considered to be related to its aetiology. In ATL endemic areas, HTLV-I carriers form a fairly high percentage of the population, even among healthy individuals. ATL shows diverse clinical features. It can be divided into four subtypes: acute, chronic, smouldering and lymphoma type. ATL cells originate from the CD4-positive subset of peripheral T cells; they show a characteristic notch in the nucleus and a tendency to lobulation. ATL resists chemotherapy, and patients with acute and lymphoma types have a fairly poor prognosis. A definite diagnosis of ATL is made by documenting the presence of HTLV-I proviral DNA in the DNA of tumour cells. HTLV-I infection is caused by transmission of live lymphocytes via three routes (from mother to child, from males to females, and by transfusion). Familial occurrence of ATL is frequently seen. HTLV-I infection is seen in other countries, but its incidence is highest in Japan. Infection with HTLV-I is a direct cause of ATL. Furthermore, infection with this virus can indirectly cause many other diseases via the induction of immunodeficiency, such as chronic lung disease, opportunistic lung infection, cancer of other organs, monoclonal gammopathy, chronic renal failure, strongyloidiasis, non-specific dermatomycosis, HTLV-I-associated lymphadenitis, HTLV-I uveitis and HTLV-I-associated myelopathy-tropical spastic paraparesis (HAM/TSP).

Absence of HTLV-I infection among seronegative subjects in an endemic area of Japan

To examine the prevalence of infection by human T-cell leukemia virus type I (HTLV-I) among seronegative subjects, healthy subjects on Tsushima Island, Japan, where the infection is endemic, were evaluated. A total of 209 healthy adults were examined for HTLV-I provirus in peripheral blood mononuclear cells by the polymerase chain reaction (PCR), as well as for anti-HTLV-I antibodies by the particle agglutination (PA) method, the enzyme-linked immunosorbent assay (ELISA) and by immunofluorescence analysis (IF). A total of 76 subjects were positive and 133 were negative for the provirus, showing a close correlation with the results of 3 assays for anti-HTLV-I serum antibodies. None of the seronegative subjects reacted positively on PCR analysis. These observations indicate that seronegative HTLV-I carriers are rare in an area of Japan in which this viral infection is endemic.

Polymerase chain reaction for diagnosis of infectious diseases

The polymerase chain reaction (PCR) has been utilized and demonstrated to be useful for detecting minute amounts of a wide variety of infectious agents. In such studies, one must keep in mind that the most appropriate conditions for amplification vary with organisms of interest. In this study, PCR was used as a rapid and sensitive method for detecting infectious agents for which three assay systems were devised comprising the method for the amplification of human T cell leukemia virus type I, Mycobacterium tuberculosis and Mycoplasma pneumoniae. The possibility of vertical transmission of human T cell leukemia virus type I through cord blood was demonstrated using cord blood mononuclear cells from carrier mothers of this virus. In the study of Mycobacterium tuberculosis, PCR was shown to be efficient, particularly in detecting this organism in extrapulmonary cases. Evidence of direct invasion into the central nervous system by Mycoplasma pneumoniae and the concomitant occurrence of mycoplasmaemia in the mycoplasmal central nervous system involvement was obtained using PCR. These results validated the potential of PCR in the clinical research of infectious diseases.

Six Colombian patients with adult T-cell leukemia/lymphoma

Six Colombian patients with adult T-cell leukemia/lymphoma (ATL) are presented. The clinical and hematological features, the familial clusters of human T lymphotropic virus type 1 (HTLV-I) carriers and the prognoses of the Colombian ATL patients were similar to those previously reported for Japanese ATL patients. The only difference was the mean age of onset, which was more than 20 years younger than in Japanese patients. Three patients with ATL were suffering from strongyloidiasis. In one patient it was suggested that ATL developed after horizontal transmission from his wife. In addition, there was a familial case of ATL and HAM/TSP. It seems that in some areas of Colombia, not only HTLV-I infection and HAM/TSP but also ATL are highly endemic.