Prevalence of HTLV-I in Arctic regions

Dermatology in the North American Indian/Alaska Native population

Dermatology is greatly understudied in the American Indian/Alaska Native (AIAN) population. This topic deserves attention in light of the changing demographics of the United States and the healthcare disparities faced by AIAN, including access to dermatologic care. In this review, we discuss disorders that are more prevalent or otherwise important in the AIAN population, such as cutaneous malignancies, photodermatoses, acanthosis nigricans, connective tissue disorders, cutaneous infections, hypertrophic scar formation, and Heck's disease. We aim to provide an updated review and increase awareness of the dermatologic needs of the AIAN population.

Insights into origins of Human T-cell Lymphotropic Virus Type 1 based on new strains from aboriginal people of Canada

The causes of the worldwide distribution of Human T-cell Lymphotropic Virus Type 1 (HTLV-1) remain incompletely understood, with competing hypotheses regarding the number and timing of events leading to intercontinental spread on historical and prehistoric timescales. Ongoing discovery of this virus in aboriginal populations of Asia and the Americas has been the main source of evidence for the latter. We conducted molecular phylogenetic and dating analyses for 13 newly reported HTLV-1 strains from Canada. We analyzed two full-length proviral genomes from aboriginal residents of Nunavut (an autonomous territory in Northern Canada including most of the Canadian Arctic), 11 long-terminal-repeat (LTR) sequences from aboriginal residents of British Columbia's Pacific coast, and 2 LTR sequences from non-aboriginal Canadians. Phylogenetic analysis demonstrated a well-supported affinity between the two Nunavut strains and two East Asian strains, suggesting the presence of an Asian-American sublineage within the widespread "transcontinental" subgroup A clade of HTLV-1 Cosmopolitan subtype a. This putative sublineage was estimated to be 5400-11,900 years in age, consistent with a long-term presence of HTLV-1 in aboriginal populations of the Canadian Arctic. Phylogenetic affinities of the other 11 Canadian HTLV-1 aboriginal strains were diverse, strengthening earlier evidence for multiple incursions of this virus into coastal aboriginal populations of British Columbia. Our results are consistent with the hypothesis of ancient presence of HTLV-1 in aboriginal populations of North America.

Demonstration of HTLV-Related Pro viral DNA Sequences and Antibodies Reactive with HTLV Internal Proteins in an Hungarian Patient with Sézary Syndrome

DNA sequences distantly related to the proviral DNA of HTLV-I were found in the leukemic cells of a Hungarian patient suffering from Sézary syndrome. Serum samples from the patient contained antibodies reactive with the internal core polypeptides of HTLV-I and HTLV-II, but not with the env gene encoded type-specific HTLV antigens. The husband and daughter of the patient also had antibodies of the same specificity. These findings suggest the presence of a virus distantly related to HTLV-I and HTLV-II.

HTLV-I infection associated with disease in aboriginal Indians from British Columbia: a serological and PCR analysis

BACKGROUND

Recent epidemiology studies have demonstrated the presence of HTLV-I and its close relative, HTLV-II in several aboriginal populations in North, Central and South America but not in Canadian Indian populations. HTLV-II appears to be more prevalent than HTLV-I in aboriginal populations of the Americas. Recently several clinical cases of HTLV-I associated myelopathy/tropical spastic paraparesis (HAM/TSP) and a case of adult T-cell leukemia (ATL) have been identified in British Columbian Indians. This data suggests that a new endemic area of HTLV-I infection may be present within British Columbian Indian population. However, it has recently been shown that HTLV-II may also be associated with a neurological disease similar to HAM/TSP.

OBJECTIVES

The purpose of the work reported here was to demonstrate whether HTLV-I, HTLV-II or both were responsible for the diseases seen in the British Columbian Indians.

STUDY DESIGN

In this study serological and gene amplification techniques were used to determine whether HTLV-I or HTLV-II was present in four families and three unrelated individuals all from different bands of aboriginal Native Indians in British Columbia. In each family, one member had an HTLV-associated disease, three cases of HAM/TSP and one case of ATL. Of the three individual aboriginal natives unrelated to the four families, two had HAM/TSP while the third was asymptomatic for HTLV-associated diseases.

RESULTS

This study demonstrated the presence of HTLV-I in the aboriginal Indians with disease and in some of their family members. HTLV-II was not detected in any of the British Columbian Indians tested in this study.

CONCLUSIONS

These British Columbian Indians represent the first Canadian aboriginal Indians with HTLV-I infection and associated diseases. Furthermore, the British Columbian Indian population may represent a previously unrecognized endemic population of HTLV-I infection.

Human endogenous retroviruses: nature, occurrence, and clinical implications in human disease

Retroviral diagnostics have become standard in human laboratory medicine. While current emphasis is placed on the human exogenous viruses (human immunodeficiency virus and human T-cell leukemia virus), evidence implicating human endogenous retroviruses (HERVs) in various human disease entities continues to mount. Literature on the occurrence of HERVs in human tissues and cells was analyzed. Substantial evidence documents that retrovirus particles were clearly demonstrable in various tissues and cells in both health and disease and were abundant in the placenta and that their occurrence could be implicated in some of the reproductive diseases. The characteristics of HERVs are summarized, mechanisms of replication and regulation are outlined, and the consistent hormonal responsiveness of HERVs is noted. Clear evidence implicating HERV gene products as participants in glomerulonephritis in some cases of systemic lupus erythematosus is adduced. Data implicating HERVs as etiologic factors in reproductive diseases, in some of the autoimmune diseases, in some forms of rheumatoid arthritis and connective tissue disease, in psoriasis, and in some of the inflammatory neurologic diseases are reviewed. The current major needs are to improve methods for HERV detection, to identify the most appropriate HERV prototypes, and to develop diagnostic reagents so that the putative biologic and pathologic roles of HERVs can be better evaluated.

Atypical human T-cell lymphotropic virus type-I-associated T-cell lymphoma in a low-prevalence Alaska Native population. Implications for disease surveillance

An atypical case of adult T-cell leukemia/lymphoma (ATL) associated with human T-cell lymphotropic virus type I (HTLV-I) occurred in a 46-year-old Inupiat Eskimo man with no behavioral risk factors for HTLV-I infection. The case was characterized by lack of atypical circulating lymphocytes, hypercalcemia, and opportunistic infections; and by complete remission of the initial renal parenchymal lymphoma. The lymphoma cells had a helper T-cell (CD4) immunophenotype. Serum antibodies to HTLV I/II, detected by Western immunoblot, were identified in specimens collected 31 months before the onset of illness, at the time of diagnosis, and up to 37 months later, shortly before the patient's death. Polymerase chain reaction was used to identify HTLV-I DNA in peripheral blood mononuclear cells and in lymphoma in involved skin. Clinicians should be alert to sporadic cases of both atypical and classic ATL, even in populations in which the prevalence of HTLV-I infection is low.

Antenatal survey for the seroprevalence of HTLV-1 infections in the West Midlands, England

The sera of 3522 women who attended an antenatal clinic in Birmingham, England were tested anonymously for antibodies against HTLV-1. Samples from 5 women (0.14%) were positive, one serum showed indeterminate reactivity. Two of the women (0.06%) were born in the West Indies (of Afro-Caribbean ethnic origin), one (0.03%) in Africa (of African ethnic origin), and three (0.09%) were white Caucasian women born in the UK. Thus, HTLV-1 infection in pregnant women in the UK, though comparatively rare, is not negligible. As transmission of HTLV-1 to the newborn via breast milk has been observed and as seropositive mothers can be advised to refrain from breastfeeding or to treat their milk, the question of routine screening for HTLV-1 infection during antenatal care is discussed.

HTLV-related markers in a Hungarian patient with adult T-cell leukemia

Monoclonal integration of DNA sequences related to, but not identical to HTLV-I provirus was detected in the peripheral blood lymphocytes of a Hungarian male suffering from ATL. The patient and his parents showed serological cross-reactivity with both HTLV-I and HTLV-II group-specific antigens. Restriction enzyme analysis with EcoRI, PstI, BamHI, HindIII and SacI revealed structural similarity of the provirus integrated in the DNA of ATL cells to HTLV-I but not to HTLV-II. Data suggest that this provirus and HTLV-I are similar to each other along gag and pol regions, but they are different in the env region.

The epidemiology of HTLV-I infection

It has been 10 years since the discovery of the human T-cell lymphotropic virus type I (HTLV-I), the first human retrovirus. During the past decade, significant progress has been made in understanding the transmission of the virus and defining its geographic distribution. It has been shown conclusively that HTLV-I is a causal factor in the induction of both adult T-cell leukemia/lymphoma and HTLV-I-associated myelopathy. However, the pathogenesis of each of these conditions is not clear, and in the light of the evidence of immune dysfunction seen among carriers of the infection, it is likely that other associated diseases will be identified. The challenge in the next decade will be to develop and implement therapeutic interventions among carriers to prevent such diseases as well as to curtail transmission within endemic populations.

Prevalence of antibodies interactive with HTLV-I antigens in selected Solomon Islands populations

Serum samples obtained in 1986 from healthy individuals in three distinct Solomon Islands populations were screened for antibodies to human lymphotropic virus type I (HTLV-I). One of the populations tested lives on the remote Polynesian outlier atoll, Ontong Java. The other two groups, the Baegu and the Lau, are Melanesians living on Malaita, the most populous of the larger Solomon Islands. Eighty-eight of a total of 601 (14.6%) sera tested were repeatably reactive in an enzyme-linked immunosorbent assay (ELISA) that uses as antigen a lysate of HTLV-I viral particles. The prevalence of antibodies interactive with HTLV-I viral particles. The prevalence of antibodies interactive with HTLV-I antigens varied among the three groups, ranging from 8.5% (16/188) in the Baegu, through 13% (7/54) in the Lau, to 18.1% (65/359) among the Ontong Java population. The specificity of the screening ELISA was confirmed by protein immunoblot. No serum samples were obtained from children under 9 years of age. Although 121 of the 601 sera came from children between the ages of 9 and 19, none of these were reactive in the HTLV-I ELISA. Starting in the third decade, the prevalence of HTLV-I seropositivity increased with age, from 8.8% (10/113) between the ages of 20 and 29 to a peak of 25.9% (15/58) and 25% (15/60) in the sixth and seventh decade, respectively. This age-specific prevalence pattern is strikingly similar to that which is seen in populations where HTLV-I infection is endemic.

Epidemiology of human T-cell leukaemia/lymphoma virus type 1 (HTLV-1) infections in a subpopulation of Afro-Caribbean origin in England

Epidemiological studies on neurological diseases in residents of Afro-Caribbean origin in the West Midlands region of England have identified eight patients with tropical spastic paraparesis (TSP), all of whom were found to be infected with human T-cell leukaemia/lymphoma virus type 1 (HTLV-1). The husband of one of the patients with TSP was also infected with HTLV-1 and had a T-cell lymphoma. In addition, six asymptomatic HTLV-1-infected first-degree relatives of the TSP patients have been found. By anonymous testing of over 700 sera obtained from individuals of Afro-Caribbean, African, or Asian ethnic origin, seven HTLV-1-infected individuals were detected, who were all immigrants from the Caribbean. Overall, these numbers yielded a seroprevalence of HTLV-1 infections of 3.4% among the immigrant population of Afro-Caribbean origin, which is comparable with the prevalence of HTLV-1 in Jamaica in an equivalent age and sex cohort. Sera were tested for HTLV-1 antibody by means of three different procedures: passive particle agglutination test (Serodia), indirect enzyme-labeled immunosorbent assay (ELISA; Dupont), and indirect immunofluorescence test (in-house, using HTLV-1-infected MT2 cells). The results of all three tests correlated very well with each other. HTLV-1 antibody titres in TSP patients were on the whole significantly higher than those of asymptomatic carriers, but some of the apparently healthy first-degree relatives and one anonymously tested individual had titres as high as most of the TSP patients.

No evidence for true HTLV-I or HIV-1 antibodies in Finnish Lapps

Previous seroepidemiologic studies have suggested that in addition to certain subtropical and tropical parts of the world, human T cell leukemia virus type I (HTLV-I) may be endemic in the arctic regions, too. We studied 111 sera collected from original inhabitants of Finnish Lapland with ELISA and Western blot analysis for antibodies to HTLV-I and human immunodeficiency virus type 1 (HIV-1). No true positive sera for either virus were found in the confirmatory Western blot assays, albeit 6 and 2%, respectively, were positive in the screening ELISA assays. Despite the small sample size this survey does not support the hypothesis that HTLV-I would be endemic in the Arctic.

Human T-cell leukemia virus-I and hematologic malignancies in Panama

Serum samples were obtained in a 2-year period (November 1, 1984-December 31, 1986) from 136 Panamanian patients with hematologic malignancies identified by a population-based registry designed for studies investigating human T-cell lymphotropic virus (HTLV)-I. Only three patients had clinical and serologic findings of HTLV-I-associated adult T-cell leukemia/lymphoma (ATLL). The authors conclude that although classical HTLV-I-associated ATLL occurs in the Panamanian population, it is not as prevalent as in other Caribbean populations.

Geographic distribution of HTLV-I and identification of a new high-risk population

Epidemiologic studies indicate that human T-cell lymphotropic virus type I (HTLV-I), the causative agent of most cases of adult T-cell leukemia/lymphoma (ATLL) in Southeast Japan and the Caribbean islands and the probable cause of a progressive neurological disorder often referred to as tropical spastic paraparesis, occurs with unusual geographic clustering. The current large-scale serosurvey was undertaken to improve our understanding of HTLV-I prevalence in different parts of the world. We analyzed 43,445 serum samples collected from various geographic locales worldwide; 76% of these sera came from clinically healthy donors. Samples were initially screened by an enzyme-linked immunosorbent assay (ELISA) and 4,353 were further evaluated by means of competition assays. In this study, which did not include sera from endemic areas of Japan, a high prevalence of infection was observed in several countries in the Caribbean basin. A significant age-sex difference was observed between populations in the Caribbean and non-endemic regions of Japan. The reason for the male excess in non-endemic areas of Japan will require further study, while the female excess in the Caribbean basin is compatible with the previously described pattern for other HTLV-I-endemic areas. A newly recognized area of possible endemicity was southern Florida, where evidence of infection with HTLV-I or a related virus was found in a group of native Americans whose sera were collected in 1968. In certain parts of the world, particularly sub-Saharan Africa, important problems in determining specificity of reactivity occurred, probably because of cross-reacting antibodies. No pattern was detected that could explain the cross-reactivity solely on the basis of geographic areas, specific patterns of non-viral parasitic infection, or methods of handling the specimens. It is possible that these cross-reactivities are antibodies to proteins from HTLV-I-related retroviruses yet to be discovered.

Manifestations of human T-lymphotropic virus type I infection

HTLV-I, the first human oncovirus, is a type C retrovirus linked to the development of ATLL. The virus shows a striking ethnogeographic distribution that is only partially understood. Certain populations at high risk for AIDS appear to have a higher incidence of HTLV-I infection. The extended latent period renders present knowledge of the sequelae and natural history of HTLV-I seropositivity incomplete, although recent data suggest that HTLV-I infection may have important implications for blood transfusion, organ transfer, and public health policy. A variety of clinical syndromes have been associated with infection, ranging from an asymptomatic carrier state to acute ATLL with lymphadenopathy, hepatosplenomegaly, hypercalcemia, cutaneous lesions, and systemic immunosuppression. Conventional chemotherapy is marginally effective; innovative approaches to therapy are presently being evaluated.

Ethnic composition, age and sex, together with location and standard of housing as determinants of HLTV-I infection in an urban Trinidadian community

The presence of antibody to human T-cell leukaemia virus (HLTV-I) has been assessed in 2,143 men and women who represent 83% of all adults aged 35 to 69 years resident in a defined urban community in Trinidad. Individuals of African descent had a higher sero-positivity rate (7.0%) than those originating from India (1.4%), Europe (0%) or of mixed descent (2.7%). Women were infected more frequently than men, and the prevalence of infection increased with age in both sexes. Sero-positivity rates were significantly increased in adults who lived in housing of poor quality (p less than 0.001) or close to water courses (p less than 0.025). These data and others raise the possibility that one route of HLTV-I transmission may be via insect vectors under particular domestic circumstances.