Infection with human T-cell leukemia virus type I in patients with leukemia

Oncogenic Viral Infections Among Iranian Hemodialysis Patients: A Systematic Review

Introduction:

Chronic hemodialysis is a lifesaving procedure for end-stage renal failure patients who may lead to the transmission of oncogenic viral infections discussed as a major cause of liver disease and a potential cause of substantial morbidity and mortality. In this regard, the hepatitis B virus (HBV) and hepatitis C virus (HCV) are the most common infections that studied recently. This study aimed to review systematically all available documents on the prevalence of hepatitis D virus (HED), hepatitis E virus (HEV), hepatitis G virus (HGV), human T-lymphotropic virus (HTLV), human immunodeficiency virus (HIV), and Kaposi's sarcoma-associated herpes virus (KSHV) in Iranian hemodialysis patients.

Methods:

We conducted a comprehensive systematic review of literature on the prevalence and factors associated with HED, HEV, HGV, HTLV, HIV, and KSHV in Iranian hemodialysis patients. Using Medical Subject Headings (MeSH) terms, Emtree, and related equal Persian key words, irrespective of age, date, and language, the main domestic databanks of Barekat, Scientific Information Database (SID), Iran-doc, and also international databases of PubMed and NLM Gateway (for MEDLINE), Institute of Scientific Information (ISI), and SCOPUS searched. Interest outcome of infection prevalence was confirmed based on reported positive tests of blood samples. Since the studied factors are very numerous and there is even a high heterogeneity in each factor, so the meta-analysis was not performed.

Results:

Based on our search strategy through comprehensive searching, 509 studies were found. From them, 314 articles were from international data bases and others from Iranian data banks. After excluding duplicates and overlapping studies, 41 studies were included in the analysis; 11 studies were relevant to HIV, 10 studies assigned to HEV, and 7 studies belonged to HGV field. The HDV, HTLV1,2, and KSHV were the other research subject areas. The prevalence of HIV, HGV, and HTLV1,2 ranged from 0% to 1.5%, 0% to 24.19%, and 0.6% to 70.4%, respectively, in different provinces.

Conclusions:

This is the comprehensive systematic review on oncogenic viral infections prevalence in the Iranian hemodialysis patients. Present findings emphasize on requirement to evidence-based practical intervention for better prevention and control of problem. The findings could be used as a scientific evidence for developing related policies and highlighting the future plan of complementary researches.

Prevalence and risk factors for Human T-Lymphotropic Virus Type 1 (HTLV-1) among maintenance hemodialysis patients

Background

Infection with the human T-cell lymphotropic virus type 1 (HTLV-1), although asymptomatic in most cases, can lead to potentially grave consequences, such as adult T-cell leukemia-lymphoma and HTLV-1-associated myelopathy / tropical spastic paraparesis. Its prevalence varies widely across different populations and geographic regions. A population-based study in the city of Salvador, located in the Northeast region of Brazil, showed an overall prevalence of HTLV-1 seropositivity of 1.7%. Blood borne virus infections are recognized as important hazards for patients and staff in maintenance hemodialysis (MHD) units but most studies focus on hepatitis B, hepatitis C and human immunodeficiency viruses. There are scarce data about HTLV-1 infection in the MHD population. We aimed to determine the prevalence and risk factors for HTLV-1 infection among MHD patients in the city of Salvador-Bahia, Brazil.

Methods

We conducted a multi-center, cross-sectional study nested in a prospective cohort of MHD patients enrolled from four outpatient clinics. HTLV-1 screening was performed with ELISA and positive cases were confirmed by Western Blot. Factors associated with HTLV-1 seropositivity were identified by multivariable logistic regression.

Results

605 patients were included in the study. The overall prevalence of HTLV-1 infection was 2.48% (15/605), which was similar to that of hepatitis B [1.98% (12/605)] and C [3.14% (19/605)] viruses in our sample. HTLV-1 seropositivity was positively associated with age [prevalence odds ratio (POR) 1.04; 95% confidence interval (CI) 1.01–1.08], unmarried status (POR 3.65; 95% CI 1.13–11.65), and history of blood transfusion (POR 3.35; 95% CI 1.01–11.13).

Conclusions

The overall prevalence of HTLV-1 infection in a sample of MHD patients was similar to that of other viral infections, such as hepatitis B and C. Our data revealed that MHD patients who are older, unmarried or who have received blood transfusions are at higher risk for HTLV-1 infection.

Infections in Patients with Cancer: Overview

Patients with neoplastic disease are often highly susceptible to severe infections. The following factors influence the types, severity, and response to therapy of these infections: (1) Changing epidemiology of infections; (2) cancer- and/or treatment-associated neutropenia; (3) acquired immune deficiency states such as cellular immune defect; (4) recent development of new-generation diagnostic tools including widely available DNA amplification tests; (5) effective intervention for infection prevention; (6) empiric or presumptive therapy during high-risk periods; (7) availability of new classes of highly active antimicrobial drugs; (8) strategies to promote hosts’ immune response; and (9) future measures. This introductory chapter intended for the reader to become familiar with the important historical milestones in the understanding and development in the field of infectious diseases in immunosuppressed patients with an underlying neoplasms and patients undergoing hematopoietic stem cell trans­plantation.

Prevalence of HTLV-I-associated T-cell lymphoma

In order to assess the prevalence rate of HTLV-1-associated T-cell lymphomas and human retrovirus infection in general, approximately 21,000 individuals representing various patient populations, retroviral risk groups, and blood donors were examined for HTLV-I, HTLV-II, HIV-1, or HIV-2 infection using serologic and PCR assays. The prevalence rates among volunteer blood donors were 0.02% and 0% for HTLV and HIV, respectively. Significantly increased HTLV prevalence rates were observed among paid blood donors, African American health care clinic patients, Amerindians, recipients of HTLV-positive cellular blood products, intravenous drug users, sexual contacts and family members of HTLV-positive people, and patients with primary thrombocytosis and other-than-low-grade non-Hodgkin's lymphoma (NHL). Among some of these groups there were significant differences in the prevalence of HTLV-I versus HTLV-II. The eight HTLV-positive NHL patients all had mature, high-grade, CD4+ T-cell lymphomas with clonally integrated HTLV-I, for a prevalence of 4% among other-than-low-grade NHL patients. Seven of the eight died from their disease within 2 years despite treatment. Interestingly, two groups at risk for HTLV infection, namely needle stick victims and recipients of HTLV-infected and/or pooled plasma products, showed no evidence for infection. Significantly increased HIV-1 prevalence was observed among paid blood donors, African Americans, homosexuals, female prostitutes, hemophiliacs, and other-than-low-grade NHL patients. Only one patient was infected with HIV-2. Of the nine HIV-positive, other-than-low-grade NHL patients, seven HIV-1 positives had B-cell lymphomas, one HIV-1 positive had an HTLV-I-positive CD4+ T-cell lymphoma, and one infected with HIV-2 had a CD4+ T-cell lymphoma that was HTLV negative. The data indicate that HTLV-I lymphoma, while uncommon, is not necessarily rare among other-than-low-grade NHL cases in the United States and, given its poor prognosis, should probably be studied separately in clinical trials.

Global epidemic of human T-cell lymphotropic virus type-I (HTLV-I)

Infection with human T-cell lymphotrophic virus-I (HTLV-I) is now a global epidemic, affecting 10 million to 20 million people. This virus has been linked to life-threatening, incurable diseases: adult T-cell leukemia/lymphoma (ATLL) and HTLV-I-associated myelopathy/tropical spastic paraparesis (HAM/TSP). The cumulative lifetime risk of developing these incurable diseases is approximately 5% in asymptomatic patients. For the emergency physician practicing among patients from high-risk groups, HTLV-I and its associated diseases are presenting an increasing challenge. This report describes its transmission, seroprevalence, treatment, and methods of controlling spread of this retrovirus. Coinfection with HTLV-I and HIV has been shown to accelerate the progression of acquired immune deficiency syndrome (AIDS).

Seroprevalence of HTLV-I and HTLV-II among a cohort of HIV-infected women and women at risk for HIV infection. Women's Interagency HIV Study

OBJECTIVES

To determine the seroprevalence of, and risk factors for, HTLV-I and HTLV-II infection among HIV-infected women and women at high risk for HIV infection.

DESIGN

Cross-sectional analysis of baseline data for women enrolled in the prospective Women's Interagency HIV Study (WIHS).

METHODS

From October 1994 through November 1995, 2657 women from five metropolitan areas in the United States (Chicago, Los Angeles, New York City [two sites], Northern California, and Washington DC) were enrolled in WIHS. An interview-based survey collected data on demographics, behavior, and medical history. HTLV-I and HTLV-II determinations were made using a combined HTLV-I/HTLV-II indirect immunofluorescent antibody (IFA) screening test, an IFA titration specificity test, and individual HTLV-I and HTLV-II confirmatory Western blots. Fisher's exact tests and logistic regression were used to determine univariate and multivariate independent predictors for HTLV-II infection.

RESULTS

Of 2625 women enrolled in WIHS with confirmed HIV results, 2487 (95%) were tested for HTLV-I and HTLV-II. Of these, 241 (10%) were HTLV-II-seropositive and 13 (0.5%) were HTLV-I-seropositive. On multivariate analysis, independent predictors of HTLV-II infection included injection drug use (OR = 5.2; p < .001), black race (OR = 3.6; p < 0.001), age >35 years (OR = 3.3; p < .001) and a history of sex with a male injecting drug user (OR = 1.9; p < .001). Among women infected with HIV, the seroprevalence of HTLV-II was 11% compared with 6% for women at risk for HIV but not infected (p < .001). However, HIV was not an independent predictor of HTLV-II infection in multivariate analysis.

CONCLUSIONS

This cross-sectional analysis confirms that HTLV-II is found commonly in HIV-infected women and uninfected women at risk for HIV in major urban areas throughout the United States and that HTLV-II is far more common than HTLV-I in these populations. Although injecting drug use is most strongly associated with HTLV-II infection, sexual transmission likely contributes to the high HTLV-II seroprevalence in this cohort.

The origin and evolution of human T-cell lymphotropic virus types I and II

Studies on human T-cell lymphotropic virus types I (HTLV-I) and II (HTLV-II) are briefly reviewed from the viewpoint of molecular evolution, with special reference to the evolutionary rate and evolutionary relationships among these viruses. In particular, it appears that, in contrast to the low level of variability of HTLV-I among different isolates, individual isolates form quasispecies structures. Elucidating the mechanisms connecting these two phenomena will be one of the future problems in the study of the molecular evolution of HTLV-I and HTLV-II.

Human T-cell lymphotrophic virus type-I (HTLV-I) retrovirus and human disease

Human T-cell lymphotrophic virus type-I (HTLV-I) was the first pathogenic retrovirus identified in humans. HTLV-I is now linked to a number of clinical diseases, most notably adult T-cell leukemia/lymphoma and the syndrome known as HTLV-associated myelopathy or tropical spastic paraparesis (HAM/TSP). For the emergency physician practicing among patients from high-risk groups, HTLV-I infection and its associated diseases are presenting an increasing challenge. This report describes its transmission, seroprevalence, associated diseases, and methods to control the spread of this retrovirus.

Seroprevalence of human T-lymphotropic virus in blacks from a selected central Brooklyn population

Human T-cell leukemia virus type I (HTLV-I) has been causally linked to adult T-cell leukemia/lymphoma and tropical spastic paraparesis/HTLV-I-associated myelopathy. Few seroprevalence studies have been carried out in the United States. Because of the number of reports of adult T-cell leukemia/lymphoma and tropical spastic paraparesis/HTLV-I-associated myelopathy in blacks from central Brooklyn, New York, we decided to initiate a seroprevalence study in this community. Intravenous drug users and male homosexuals were excluded. A total of 480 individuals from medical clinics and health fairs were surveyed via questionnaire, and their sera were assayed for HTLV-I/II antibody by two laboratories. An overall seroprevalence rate was 21/480 (4.4%). This is almost 200 times greater than a study of a national sample of U.S. blood donors. Rates were similar for individuals originating from the United States and the Caribbean. Nine of the 21 seropositive individuals returned for further testing. Polymerase chain reaction assays revealed that 8 were positive for HTLV-I and 1 for HTLV-II. Although this group may not be representative of the "normal" black population of central Brooklyn, the high seroprevalence rate necessitates that the incidence of HTLV-I-associated illnesses be determined in this community.

Reduction of HTLV-I-infected cells in blood by leukocyte filtration

Leukocyte filtration was performed with HTLV-I-infected blood and with blood supplemented with cultured HTLV-I-transformed cells. Reduction of infectivity upon leukocyte filtration was determined by the polymerase chain reaction (PCR) using primers indicative for the HTLV-I-pol and tax genes. Two different commercially available filters were used: a column-shaped cellulose acetate and a flat-bed polyester filter. Both filters yielded reduction of at least 3 10logs for cultured HTLV-I-infected cells. When blood from HTLV-I-infected individuals was used for filtration, the number of infected cells was reduced by 1-3 10logs. Although filtered blood as yet cannot be regarded as safe, it is concluded that leukocyte filtration of HTLV-I-infected blood potentially contributes to reducing the spread of HTLV-I by blood transfusion.

Prevalence of antibodies to human T cell leukaemia/lymphoma virus in blood donors in north London

OBJECTIVES

To determine the prevalence of antibodies to the human T cell leukaemia/lymphoma viruses (HTLV-I and HTLV-II) in blood donors in north London in order to assess the economic impact and the logistic effects that routine screening would have on the blood supply.

DESIGN

All donations collected by the north London blood transfusion centre between January 1991 and June 1991 were screened for antibodies to HTLV-I and HTLV-II by modified, improved Fujirebio gel particle agglutination test. Positive samples were titrated and retested as necessary.

SUBJECTS

96,720 unpaid volunteers, who gave 105,730 consecutive donations of blood and plasma.

SETTING

North London blood transfusion centre.

MAIN OUTCOME MEASURE

Observed numbers of donors confirmed to be seropositive for HTLV by reference laboratories.

RESULTS

Of 2622 (2.5%) initially reactive samples, 414 (0.4% of all samples) gave a titre of > or = 1 in 16 on the modified agglutination test. Thirty five of the 414 serum samples yielded positive results on one of two enzyme linked immunosorbent assays (ELISA (Cambridge Biotech and Abbot)), and none of these results were confirmed by either reference laboratory. Five samples yielded positive results on both ELISAs and all five of these were confirmed to contain antibodies to HTLV. One of the five contained antibodies to HTLV-II and the others antibodies to HTLV-I. Four seropositive donors were white women whose only risk factor for infection was sexual contact. The fifth (positive for antibodies to HTLV-II) was an Anglo-Caribbean man who admitted to previous misuse of intravenous drugs.

CONCLUSION

The prevalence of antibodies to HTLV in blood donors in north London was one in 19,344 (0.005%). Up to 100 donors a year might be identified in the United Kingdom as being infected with HTLV, although prevalence in different regions may vary considerably.

Indications for the presence of antibodies cross-reactive with HTLV-I/II, but not HIV, in patients with myelodysplastic syndrome

Serological evidence is presented for the fact that patients with the myelodysplastic syndrome exhibit a statistically significant reactivity in confirmatory assays for antibodies to human T-lymphotropic viruses types I and II (HTLV-I/II). This antibody reactivity, evident by indirect immunofluorescence and Western blot, was not confined to HTLV core antigens but extended to native and recombinant envelope glycoproteins. The effect was also observed in cases of acute myeloic leukemia, albeit to a lesser degree. It was essentially absent from patients with chronic myeloic leukemia or lymphocytic leukemias and healthy or multitransfused controls. No antibodies to human immunodeficiency viruses types 1 or 2 were detected in any of the specimens. The investigated clinical population had no known risk factor for retroviral infection other than a history of multiple platelet transfusions, and none of the specimens was seropositive for HTLV-I or HTLV-II according to recommended criteria. The cause of this cross-reactivity remains to be determined.

Acute adult T-cell leukemia/lymphoma presenting with florid cutaneous disease

Adult T-cell leukemia/lymphoma (ATLL) is characterized by cutaneous disease, hypercalcemia, associated HTLV-I infection, and a fulminant course refractory to therapy. A patient with acute ATLL is described, and the natural history of ATLL is reviewed.

A prospective study of transmission by transfusion of HTLV-I and risk factors associated with seroconversion

To evaluate the risk of transfusion-related transmission of HTLV-I in Jamaica, a prospective study was initiated, prior to availability of a licensed HTLV-I serological screening assay. This information would prove useful in formulating strategies for blood-donor screening. We followed 118 pre-transfusion HTLV-I-negative transfusion recipients at monthly intervals post-transfusion for 1 year. Laboratory and questionnaire data were obtained at each visit to evaluate the clinical and immunological status of recipients. Cumulative incidence of HTLV-I seroconversion was estimated and risk-factor data associated with seroconversion among 66 HTLV-I-exposed transfusion recipients were analyzed. Seroconversion occurred in 24/54 (44%) of recipients of HTLV-I-positive cellular blood components, 0/12 recipients of positive non-cellular donor units and 0/52 recipients of HTLV-I-negative donor units. Significant risk factors associated with recipient seroconversion were receipt of a seropositive cellular blood component stored for less than one week [odds ratio (OR) = 6.34, 95% confidence interval (CI) = 1.83 to 21.92], male sex (OR = 4.79, 95% CI = 1.15 to 20.0) or use of immuno-suppressive therapy at time of transfusion (OR = 12.20, 95% CI = 0.95 to 156). Risk of blood-borne infection per person per year in Jamaica was estimated to be 0.009%. Our results confirm that blood transfusion carries a significant risk of HTLV-I transmission and that screening of donor blood effectively prevents HTLV-I seroconversion. Recipients at greatest risk for seroconversion were those who required multiple transfusions or who were receiving immunosuppressive therapy at the time of transfusion. These patients should be given priority in receiving selectively screened blood components, if universal blood-donor screening for HTLV-I is not possible.

A comparison of HIV-1, HBV, and HTLV-I/II seroprevalence rates of injured patients admitted through California emergency departments

STUDY OBJECTIVE

To determine the seroprevalence rates of hepatitis B virus (HBV) and human T-lymphotropic virus (HTLV-I/II) and to compare these rates with the HIV-1 seroprevalence rate in a sample of injured patients admitted through ten California emergency departments.

DESIGN

Prospective blinded testing for serologic markers for HBV, HTLV-I/II, and HIV-1 on routinely collected blood samples.

SETTING

Ten California hospitals were chosen to reflect geographic and demographic diversity.

TYPE OF PARTICIPANTS

All injured adult patients who were admitted to a participating hospital through the ED during consecutive three-month periods from June through November 1989.

MEASUREMENTS

Serum samples were tested for HIV-1 antibody, HTLV-I/II antibody, and hepatitis B surface antigen (HBsAg) using standard methods. Mann-Whitney U tests, chi 2 tests for independence, sign tests, chi 2 tests for goodness of fit, and logistic regression were used as appropriate.

RESULTS

Seroprevalence rates were as follows: HBV, 2.6% (57 of 2,209); HTLV-I/II, 2.0% (46 of 2,262); and HIV-1, 1.4% (31 of 2,264).

CONCLUSION

The seroprevalence rate of HBV was slightly higher than that of HIV-1 in this sample of injured patients. Mortality estimates suggest, however, that HBV and HIV-1 pose roughly similar risks to emergency personnel, although the risk of HBV infection can be markedly reduced by vaccination. The data from this and other studies suggest that the ED incidence of HTLV-I/II in United States is low. The relative health risks to emergency personnel from HTLV-I/II appear to be minimal at this time.

Monoclonal antibodies and chemiluminescence immunoassay for detection of the surface protein of human T-cell lymphotropic virus

Monoclonal antibodies (MAbs) raised against human T-cell lymphotropic virus type I (HTLV-I) recognized five distinct antigenic domains of viral env gene-encoded proteins. By using recombinant env proteins and synthetic peptides as mapping antigens, it was determined that the most immunogenic region represented a central portion of the retroviral surface protein (domain 2; amino acids 165 to 191). However, only a single MAb was able to react strongly with native viral proteins. This antibody (clone 6C2) was directed to an epitope within domain 4 (amino acids 210 to 306) of the retroviral env gene and reacted with envelope proteins in both HTLV-I and HTLV-II, as determined by immunoprecipitation, solid-phase binding, and immunoblotting. No reactivity against envelope components of other human retroviruses, including human immunodeficiency virus types 1 and 2, was present. Flow cytometry data demonstrated that MAb 6C2 reacted with cell lines chronically infected with HTLV-I or HTLV-II and also with surface antigens expressed on fresh adult T-cell leukemia cells, following up-regulation with interleukin-2. By a chemiluminescence immunoassay procedure, picogram amounts of viral surface protein could be detected in the unconcentrated supernatants of HTLV-infected cell lines and in diagnostic cultures. Levels of env and gag proteins released by cells into culture supernatants were not directly related to percent expression of cell surface viral-coat proteins. Further, the molar ratio of p19 to gp46 in conditioned media varied from strain to strain, possibly reflecting differences in viral assembly or packaging mechanisms. MAb 6C2 will be of value in characterizing the biochemical and immunological behavior of retroviral env gene proteins and in studying the interaction of HTLV-I and HTLV-II with their receptors.

Prevalence of human T-lymphotropic virus in civilian applicants for the United States Armed Forces

BACKGROUND

The wide range in human T-lymphotropic virus (HTLV) seroprevalences reported worldwide has made estimates of seroprevalence difficult in unique populations. In this study, the seropositivity of young adult civilian applicants for the US Armed Forces was determined.

METHODS

Serum samples from nine geographic regions were screened by an Enzyme-Linked Immunosorbent Assay (ELISA), and repeatedly reactive samples were further tested by Western blot and radioimmunoprecipitation. Specimens were scored as positive when antibody to gag (p24) and env (gp46 or gp68) were detected.

RESULTS

Of the 43,750 samples analyzed, 18 were positive for HTLV antibodies. Ten (55%) were from males and eight (45%) were from females. Nine (90%) of the males and seven (87.5%) of the females were Black. Twelve of the positive samples (66.6%) were from the New York City region, which represented only 18.8% of the sample population.

CONCLUSIONS

The overall HTLV seroprevalence of civilian applicants for the US Armed forces was 0.41 per 1000. This was higher than the seroprevalence reported for volunteer blood donors.

A serosurvey for HTLV-I among high-risk populations and normal adults in Egypt

The prevalence of antibodies to human T-cell lymphotropic virus type I (HTLV-I) was determined in high-risk groups and normal adults in Egypt. Among 647 individuals tested, 6 (0.9%) were confirmed positive by western blot analysis. These included 2 (0.7%) of 279 drug addicts, 1 (3.3%) of 30 patients with sexually transmitted diseases, and 3 (2.2%) of 133 healthy individuals. Antibody was not detected in 47 blood recipients or 158 prostitutes. There was no correlation between sex or geographical location and HTLV-I infection. Fifty-three of the 647 sera (8%) were initially reactive by ELISA, but only 12 sera were repeatedly reactive. Since only 4 of these repeatedly reactive sera were confirmed by the western blot, the frequency of false positives using the DuPont screening ELISA was 1.2% (8/643). Two additional sera, confirmed positive by western blot, had been reactive, but not repeatedly, by ELISA. In comparison to the prevalence of HTLV-I antibody among risk groups in many parts of the world, the prevalence in Egypt was low.

Human T-cell lymphotropic virus type I and II in transfusion medicine

As a consequence of migrating populations, IV drug use and, to a lesser extent, blood transfusions, endemic HTLV-I and HTLV-II infections have spread to nonendemic geographic regions. Although the risk that a person infected with HTLV-I will develop significant disease--even over a lifetime--is estimated to be relatively low, our awareness of the serious diseases associated with other retroviruses requires a cautious approach to blood transfusion. Reports from Japan and the United States indicate that programs testing donated blood and excluding units with HTLV-I antibodies have been highly successful in interrupting the spread of HTLV-I by transfusions. One unanticipated outcome of testing large numbers of people in the United States for HTLV-I antibodies has been recognition of the relatively high prevalence of HTLV-II infection, particularly among IV drug users. The long-term effects of HTLV-II infection are also unknown. Until the natural history and clinical consequences of HTLV-II infection are clearly understood, it is only prudent that blood donated by persons identified to be HTLV-II carriers also be excluded.

Evaluation of enzyme immunoassays for antibody to human T-lymphotropic viruses type I/II

To evaluate the sensitivity and specificity of HTLV-I/II assays, serum from 1100 pregnant Haitian women was tested with seven commercially available HTLV I/II assays. Serum that was found to be reactive in any assay was analysed by western blot and all indeterminate samples were further characterised by radioimmunoprecipitation assays (RIPA). 59 (5.4%) samples were HTLV I/II antibody positive by western blot and/or RIPA. The sensitivity of these seven assays ranged from 93.2% to 100%. with the 'Recombinant HTLV-I' (Cambridge Bioscience) and 'Serodia HTLV-I' (Fujirebio) assays having the highest sensitivity (100%). The specificity of these assays ranged from 98.4% to 100%, with the Abbott assay having the highest specificity (99.5%, 100%) according to two different methods of evaluation. Whether the antigens used in any assay were whole disrupted virus or recombinant gene products made no difference. The low positive predictive values of some of these assays (71.8-91.7%), even in a high prevalence population, and the need for RIPA to test indeterminate sera, indicate that for routine screening of blood donors there is still room for improvement both in screening and confirmatory assays for HTLV-I/II.

Screening for anti-human T-lymphotropic virus antibody in blood donors and polytransfused patients in Apulia (Italy)

A stringent procedure for the diagnosis of human T-lymphotropic virus (HTLV) infection was applied to 1,732 volunteer blood donors, 401 patients with various hematological disorders and 78 individuals at high risk for HIV infection. It consisted of a viral lysate-based screening assay (Abbott Laboratories, North Chicago, Ill., USA), and two confirmatory assays (Western blot and radioimmunoprecipitation assay). A confirmed positive sample had to react with at least two different HTLV gene products. Evidence of HTLV infection was not found in either blood donors or patients with hematological disorders. In fact, HTLV infection was only observed in 10 intravenous drug abusers or their sexual partners. Contrary to previous reports that claimed HTLV seroprevalences of between 0.3 and 8% in blood donors from Apulia (Italy), our data suggest that infection with this virus is principally restricted to intravenous drug abusers.

Acute T-cell leukemia/lymphoma mimicking Hodgkin's disease with secondary HTLV I seroconversion

The authors observed a pleiomorphic lymphoma mimicking Hodgkin's lymphoma in a French Guyana black woman lacking antibodies for human T-cell lymphoma/leukemia virus type I (HTLV I). After two courses of chemotherapy with either mechlorethamine, vincristine, procarbazine, and prednisone (MOPP) or doxorubicin, bleomycin, vincaleukoblastine, and dacarbazine (ABVD), a typical acute T-cell leukemia/lymphoma developed with HTLV I seroconversion. Specific HTLV I DNA sequences were detected using the polymerase chain reaction (PCR) on a lymph node biopsy obtained before chemotherapy. The mechanisms of the seroconversion are discussed.

Transmission of HTLV-II via blood transfusion

Transmission of HTLV-I by transfusion is well documented in Japan, where HTLV-I is endemic. In non endemic regions such as the United States, HTLV-I/II infection has been transmitted by transfusion as well, but no effort to distinguish HTLV-I from HTLV-II infection was made in these studies. There is a growing body of evidence that a substantial proportion of HTLV-I/II seropositivity in the US is due to infection with HTLV-II. We report 2 cases of apparent transfusion-transmitted HTLV-II infection and discuss the importance of distinguishing between the two viruses in blood donors and recipients.

Familial adult T-cell leukemia/lymphoma

Clinical and laboratory data are described for two siblings who both developed adult T-cell leukemia/lymphoma resulting from infection by human T lymphotropic virus type I (HTLV-I). These findings suggest that genetic factors or virus-specific factors may determine which HTLV-I-infected individuals will develop leukemia.

A seroepidemiological survey of HTLV-I/HTLV-II in selected Belgian populations

A preliminary survey of the prevalence of HTLV-I antibody during 1987 and 1988 in Belgium revealed no positive results among selected blood donors who sided for some length of time in areas where HTLV-I/HTLV-II is endemic (n = 270), in development-aid workers (n = 145), or in missionaries (n = 35) serving in developing countries. Among foreign groups, African students (n = 212), and political refugees (n = 311), HTLV-I/HTLV-II antibodies were detected and confirmed in 3 cases. Limited data from 1987 and 1988 suggest that HTLV-I/HTLV-II poses no major public health problem in Belgium.

Human T-cell lymphotropic virus type I (HTLV-I) antibodies in pre-diagnostic serum of patients with familial adult T-cell leukemia/lymphoma (ATL)

In a study of 7498 American men of Japanese ancestry in Hawaii, 26 incident cases of leukemia or non-Hodgkin's lymphoma were identified after a follow-up period of 19 years. Two of the cases, who were brothers, were diagnosed with adult T-cell leukemia/lymphoma (ATL). Both of these brothers had human T-cell lymphotropic virus type I (HTLV-I) antibodies in their stored serum which were obtained 4 and 18 years before diagnosis. None of the 24 patients with other hematologic malignancies or the 26 matched controls were HTLV-I antibody positive. This finding lends further support for a role of HTLV-I in the etiology of adult T-cell leukemia/lymphoma.

Examination of HTLV-I ELISA-positive leukemia/lymphoma patients by western blotting gave mostly negative or indeterminate reaction

We used enzyme-linked immunosorbant assay (ELISA) and Western blotting, with "purified" human T-cell leukemia virus I (HTLV-I), to test for HTLV-I antibodies in 2583 plasma samples from 1053 leukemia/lymphoma patients treated at Roswell Park Memorial Institute, mostly between 1972 and 1984, and in 110 sera samples from normal healthy persons. The results demonstrate that ELISA and Western blot assay have limitations for HTLV-I antibody detection in an adult T-cell leukemia/lymphoma (ATL) nonendemic population. This conclusion is based on the many false reactives obtained by ELISA, and weak and indeterminate reaction (mostly p19 band) on Western blotting. All moderate to strongly HTLV-I ELISA-positive samples tested were negative for human immunodeficiency virus (HIV) antibodies. Although 6/27 mycosis fungoides (MF) patients tested gave mostly a weak reaction on HTLV-I ELISA, 3/6 MF patients gave multiple bands (p19, p31, p36, gp46) on Western blotting and three samples from one patient gave the same p31, p36, and gp46 bands. This may suggest involvement of some HTLV-I-related virus in MF. These results also indicate that prevalence of HTLV-I infection in leukemia/lymphoma patients was rare, if it exists at all, since, despite the reactivity of some sera with HTLV-I-suspected antigens, none of the samples satisfy the USPHS criteria for positivity which is based on the detection of antibodies to gag protein p24 and to an env gene product gp46 or gp61/68.

Immunodetection of human T-cell lymphotropic virus type I core protein in biological samples by using a monoclonal antibody immunoassay

A monoclonal antibody-based enzyme immunoassay (EIA) has been developed for detection of human T-cell lymphotropic virus type I (HTLV-I) core protein. The monoclonal antibody (clone 6.11) specifically recognizes the p19 gag gene-encoded protein of the virus. The EIA was over 100 times more sensitive than reverse transcriptase measurement and was capable of responding to less than 500 pg of whole-virus lysate. The assay exhibited type specificity in that HTLV-II antigens failed to produce a positive signal. In addition, a panel of other viruses demonstrated no antigenic cross-reactivity. These included herpesviruses, measles virus, human immunodeficiency viruses, and others. Viral p19 was followed during the course of density gradient ultracentrifugation in the presence of detergent, where it was noted to associate with viral membrane proteins. In comparison, reverse transcriptase activity localized in fractions of higher density containing envelope-free cores. Of clinical interest, the EIA was used to detect HTLV-I antigen in the viral cultures of patients with HTLV-I-associated myelopathies and from symptom-free individuals with proviral integration.

Immunoserology of infectious diseases

The immune response to microorganisms not only participates in the elimination of unwanted organisms from the body, but also assists in diagnosis of infectious diseases. The nonspecific immune response is the first line of defense, assisting the body until the specific immune response can be mobilized to provide protective mechanisms. The specific immune response involves humoral or cell-mediated immunity or both, dependent on the nature of the organism and its site of sequestration. A variety of test systems have been developed to identify the causative organisms of infectious diseases. Test systems used in immunoserology have classically included methods of detecting antigen-antibody reactions which range from complement fixation to immunoassay methods. Relevant test systems for detecting antigens and antibodies are described. With numerous test systems available to detect antigens and antibodies, there can be confusion regarding selection of the appropriate system for each application. Methods for detecting antibody to verify immunity differ from immunologic methods to diagnose disease. Techniques to detect soluble antigens present in active infectious states may appear similar to those used to detect antibody, but their differences should be appreciated.

Epidemiologic assessment of screening tests for antibody to human T lymphotropic virus type I (HTLV-I)

We tested 196 sera from a human T lymphotropic virus type I (HTLV-I) risk group (prostitute women) with two commercial "research" enzyme-linked immunoabsorbent assays (EIA) for HTLV-I antibodies. All tested sera were characterized by HTLV-I Western immunoblots and by HTLV-I radioimmunoprecipitation assays. The estimated sensitivities of the EIA tests were 93.8 percent and 100 percent, and the specificities were 98.8 percent and 95.8 percent, respectively, using recommended criteria for seropositivity (requiring reactivity to both gag p24 and env gp46 or gp61/68). Calculated negative predictive values remained excellent (greater than 99.9 percent and 100 percent, respectively) at lower seroprevalence rates but the positive predictive values were only 7.3 percent and 2.3 percent when calculated for a seroprevalence rate of 0.1 percent. These results emphasize the importance and need for additional HTLV-I supplementary serologic testing when screening populations with low HTLV-I seroprevalence rates.

HTLV-1 and tropical spastic paraparesis. 2. The human T-cell lymphotropic virus type 1

Human T-lymphotropic viruses (HTLV) are causally associated with adult T-cell leukaemia and with a progressive form of lower limb paralysis known as tropical spastic paraparesis. HTLV-1 is endemic in parts of Japan, the Caribbean, West Africa and probably South America, and is associated with disease in these areas. Horizontal transmission is probably most common through sexual intercourse which, it is postulated, must be more efficient from male to female because virus carriage is more prevalent in women in endemic areas. Vertical transmission appears to be principally through breast milk. Poor housing and hygiene may facilitate transmission.

AIDS-related vacuolar myelopathy is not associated with coinfection by human T-lymphotropic virus type I

Assessment of antibodies against human T-lymphotropic virus type I (HTLV-I) by enzyme-linked immunoassay, immunofluorescence, and Western blot was undertaken in patients with pathologically or clinically diagnosed acquired immunodeficiency syndrome-related vacuolar myelopathy to determine whether this retrovirus could be etiologically implicated in this disorder. No serological evidence for HTLV-I was found in the patients with vacuolar myelopathy, though 1 patient with an atypical myelopathy did have antibodies against HTLV-I.

Seroepidemiologic survey for antibodies to human retroviruses in human and non-human primates in Brazil

The prevalence of antibodies to HTLV-I and HIV-I in Brazil was determined by testing sera from: (a) 119 members of an isolated Amazonian community of African origin; (b) 100 voluntary blood donors in Rio de Janeiro; (c) 215 patients treated at the Hematology Service, National Cancer Institute, Rio de Janeiro, and (d) 44 Cebus apella New World monkeys, wild-caught in Amazonia. Anti-HTLV-I was detected in 1 (0.84%) of 119 Amazonians, in 8 (3.72%) of the 215 patients and in none of the blood donors or monkeys. The high prevalence found in patients included 4 (5.79%) of 69 with non-Hodgkin lymphoma, 2 (5.88%) of 34 with Hodgkin lymphoma, 1 (16.66%) of 6 patients with diagnosis of anemia and 1 (20%) of 5 with HIV-I infection. Anti-HIV-I was found in 7 (14.89%) of 47 patients and in none of the other groups. The high incidence of HTLV-I infection in the patient group suggests that this retrovirus is endemic in parts of Brazil.

Transmission of retroviruses by transfusion of screened blood in patients undergoing cardiac surgery

We determined the rates of seroconversion to human immunodeficiency virus type 1 (HIV-1) and human T-cell leukemia virus Type I (HTLV-I) in a cohort of patients receiving transfusions of blood components screened for antibody to HIV-1. Preoperative and postoperative serum samples were collected from 4163 adults undergoing cardiac surgery who received 36,282 transfusions of blood components. The postoperative samples from all patients were tested for serologic evidence of HIV-1 infection, and those that were positive were compared with the corresponding preoperative samples. One case of HIV-1 transmission by transfusion of screened blood components was identified; two preexisting HIV-1 infections were found. Samples from 2749 patients were tested similarly for serologic evidence of HTLV-I infection; these patients received 20,963 units of blood components. Five new cases and two preexisting cases of HTLV-I infection were detected. The observed risk of HIV-1 transmission by transfusion was 0.003 percent per unit; the risk of HTLV-I transmission was 0.024 percent per unit. We conclude that there is a very small risk of HTLV-I infection from transfused blood products that have been screened for antibodies to HIV-1, but that it is nearly 10-fold higher than the risk of HIV-1 infection.

High rate of HTLV-II infection in seropositive i.v. drug abusers in New Orleans

Confirmed infection with HTLV-II (human T cell leukemia virus type II) has been described only in rare cases. The major limitation to serological diagnosis of HTLV-II has been the difficulty of distinguishing HTLV-II from HTLV-I (human T cell leukemia virus type I) infection, because of substantial cross-reactivity between the viruses. A sensitive modification of the polymerase chain reaction method was used to provide unambiguous molecular evidence that a significant proportion of intravenous drug abusers are infected with HTLV, and the majority of these individuals are infected with HTLV-II rather than HTLV-I. Of 23 individuals confirmed by polymerase chain reaction analysis to be infected with HTLV, 21 were identified to be infected with HTLV-II, and 2 were infected with HTLV-I. Molecular identification of an HTLV-II--infected population provides an opportunity to investigate the pathogenicity of HTLV-II in humans.