Comparison of four enzyme immunoassays for detection of human T-cell lymphotropic virus type 2 antibodies

Four licensed enzyme immunoassay (EIA) kits for the measurement of antibody to human T-cell lymphotropic virus (HTLV) type 1, one from Organon Teknika Corp. (OTC), one from Cambridge Biotech Corp. (CBC), and two from Abbott Laboratories (the 1993 modification [Abb 93] and the 2.0 version licensed in 1995 [Abb 95]), were evaluated for sensitivity and specificity in the detection of HTLV type 2 antibody, and the results were compared with those previously obtained with earlier kit versions. The CBC, Abb 95, Abb 93, and OTC kits had sensitivities of 99.7, 97.6, 96.8, and 96.2%, respectively, compared with sensitivities of 89.1 and 60% for the Abbott and CBC (previously DuPont) kits, respectively, licensed in 1988. Thus, the abilities of commercial kits to detect HTLV antibody have improved. The relative specificities of the CBC, Abb 95, Abb 93, and OTC kits with negative blood donor specimens that had been reactive with the 1988 CBC EIA kit were 92.9, 64.5, 78.8, and 62.6%, respectively. Compared with those of the 1988 versions, the specificity of the Abbott EIA has decreased and the specificity of the CBC kit has been significantly improved.

High prevalence of human T cell lymphotropic virus type II infection in patients affected by human immunodeficiency virus type 1--associated predominantly sensory polyneuropathy

The etiopathogenesis of peripheral neuropathy (PN) that frequently affects human immunodeficiency virus (HIV) type 1-positive patients remains undefined. Forty-seven HIV-1-positive patients with PN (8 with inflammatory demyelinating polyneuropathy and 39 with predominantly sensory polyneuropathy [PSP]) and 266 controls with symptomatic HIV-1 infection without PN were screened for antibodies to human T cell lymphotropic virus (HTLV) types I and II. The prevalence of antibodies to HTLV-II was significantly higher in patients with PSP than in controls (30.8% vs. 8.3%; P < .001). All seropositive patients with PN had HTLV-II DNA in their peripheral blood mononuclear cells by polymerase chain reaction (PCR) analysis. PCR analysis of tissues from 1 patient with PSP who died during the study showed HTLV-II proviral sequences in the femoral nerve and basal nuclei. These results support the hypothesis that HTLV-II represents an etiologic factor in the pathogenesis of a considerable proportion of PSP in patients infected with HIV-1.

Enhanced specificity of truncated transmembrane protein for serologic confirmation of human T-cell lymphotropic virus type 1 (HTLV-1) and HTLV-2 infections by western blot (immunoblot) assay containing recombinant envelope glycoproteins

Immunoassays based on the highly immunogenic transmembrane protein of human T-cell lymphotropic virus type 1 (HTLV-1) (protein 21c) are capable of detecting antibodies in all individuals infected with HTLV-1 and HTLV-2. However, because of antigenic mimicry with other cellular and viral proteins, such assays also have a large proportion of false-positive reactions. We have recently identified an immunodominant epitope, designated GD21-I located within amino acids 361 to 404 of the transmembrane protein, that appears to eliminate such false positivity. This recombinant GD21-I protein was used in conjunction with additional recombinant HTLV type-specific proteins and a whole virus lysate to develop a modified Western blot (immunoblot) assay (HTLV WB 2.4). The sensitivity and specificity of this assay were evaluated with 352 specimens whose infection status was determined by PCR assay for the presence or absence of HTLV-1/2 proviral sequences. All HTLV-1-positive (n = 102) and HTLV-2-positive (n = 107) specimens reacted with GD21-1 in the HTLV WB 2.4 assay, yielding a test sensitivity of 100%. Furthermore, all specimens derived from individuals infected with different viral subtypes of HTLV-1 (Cosmopolitan, Japanese, and Melanesian) and HTLV-2 (IIa0, a3, a4, IIb1, b4, and b5) reacted with GD21-I in the HTLV WB 2.4 assay. More importantly, HTLV WB 2.4 analysis of 81 PCR-negative specimens, all of which reacted to recombinant protein 21e in the presence or absence of p24 and p19 reactivity in the standard WB assay, showed that only two specimens retained reactivity to GD21-I, yielding an improved test specificity for the transmembrane protein of 97.5%. None of 41 specimens with gag reactivity only or 21 HTLV-negative specimens demonstrated reactivity to GD21-I. In an analysis of additional specimens (n = 169) from different geographic areas for which PCR results were not available, a substantial increase in the specificity of GD21-I detection was demonstrated, with no effect on the sensitivity of GD21-I detection among specimens from seropositive donors. Thus, the highly sensitive, GD21-I-based HTLV WB 2.4 assay eliminates the majority of false-positive transmembrane results, thereby increasing the specificity for serologic confirmation of HTLV-1 and HTLV-2 infections.

HTLV-I associated myelopathy in Porto Alegre (Southern Brazil)

HTLV-I associated myelopathy/tropical spastic paraparesis (TSP/HAM) have been increasingly described in practically all regions of Brazil. Five confirmed and documented cases of patients with TSP/HAM in Rio Grande do Sul are reported; in all of them spastic paraparesis, neurogenic bladder and superficial and/or profound sensitive disorders were observed in variable degrees. One patient presented a relapsing-remitting course with a cerebellar ataxia (multiple sclerosis-like pattern). Everyone was submitted to clinical, serological, urodynamic, neurophysiologic and neuroradiologic investigation. The aim of this study was to present the southern region of Brazil as an area with significant endemicity for HTLV-I/II infection (prevalence of 0.42% between blood donors), and also to show the existence of patients with neurologic disease associated with this retrovirus.

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

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

Implications of human T-lymphotropic virus type-I and type-II testing in donors and patients

The retroviruses known as Human T-Lymphotropic Virus Types I and II (HTLV-I and -II) were recognized before the human immunodeficiency virus (HIV-1). Associated diseases of HTLV-I infection, including a particular kind of leukemia or the development of a specific demyelinating disease, have also been observed. Screening of blood donors for antibodies to HTLV was mandated in November of 1988. This paper examines the biology of HTLV-I and HTLV-II and reviews the testing methods for HTLV-I/II. Data from 39,908 blood donations of volunteer donors at The University of Texas M. D. Anderson Cancer Center (UTMDACC), Division of Laboratory Medicine, Section of Transfusion Medicine are presented. Initially reactive specimens for HTLV antibodies were 158 (0.4 percent). Of these 0.26 percent or 105 of 39,908 were repeatedly reactive. Eight hundred and sixty-seven cancer patients were also tested for HTLV antibodies. Eight or 0.9 percent were repeatedly reactive for HTLV antibodies by enzyme immunoassays (EIA), but only one could be confirmed as positive. HTLV-I/II has a very low incidence in the ambulatory population. The relationship of clinical sequelae and the rate of transmission of these viruses remain unclear. A readily applicable confirmatory test is not yet available. Even significant improvements in the sensitivity and specificity of testing will present ongoing problems for identification of true HTLV carriers. The clinical decision-making process related to the meaning of these results continues to be difficult.

Seroprevalence of human T cell lymphotropic virus type II infection, with or without human immunodeficiency virus type 1 coinfection, among US intravenous drug users

Seroprevalence of human T lymphotropic virus (HTLV) and human immunodeficiency virus type 1 (HIV-1) was determined among 7841 intravenous drug users (IVDUs) from drug treatment centers in Baltimore, Chicago, Los Angeles, New Jersey (Asbury Park and Trenton), New York City (Brooklyn and Harlem), Philadelphia, and San Antonio, Texas; 20.9% had evidence of HTLV infection, as determined using a p21e EIA for screening and p21e blot for confirmation. With a type-specific EIA and blot used in combination, HTLV-II was identified in 97.6% of HTLV-positive IVDUs whose sera could be subtyped. HIV-1 seroprevalence was 13.2%. HTLV-II without HIV-1 was most common in Los Angeles and San Antonio. HIV-1 without HTLV-II was most common in New York, New Jersey, and Baltimore. Dual infection was most common in New York and New Jersey. Logistic regression analysis revealed that seroprevalence of HTLV-II was significantly greater with HIV-1 infection and increasing age and among women, blacks, and Mexican-Americans. In conclusion, it appears that among US IVDUs, nearly all HTLV infection is attributable to HTLV-II, and HTLV-II infection is associated with HIV-1 and sociodemographic background.

Identification of human T cell lymphotropic virus type IIa infection in the Kayapo, an indigenous population of Brazil

Human T cell lymphotropic virus type II (HTLV-II) infection is endemic in a number of indigenous populations in North, Central, and South America. In the present study we have employed serological and molecular methods to identify HTLV-II infection in Indian communities in the Amazon region of Brazil. Sera (1324) from 25 different Indian communities were analyzed by ELISA and Western blot. One hundred and four samples (7.8%) from a number of culturally distinct and geographically unrelated populations were found to have reactivities consistent with HTLV-II infection. Of these, 67 were from the Kayapo Indian communities, which had an overall seroprevalence rate of greater than 30%. In addition, high seroprevalence rates were observed in three other communities, the Munduruku, Arara do Laranjal and the Tyrio, suggesting that there are additional foci of endemic infection in the Amazon region. In the Kayapo, seroprevalence rates tended to increase with age, supporting the importance of sexual transmission of the virus, and family studies demonstrated that vertical transmission is also an important route of infection. Restriction fragment length polymorphism (RFLP) and nucleotide sequence analysis of a region of the env gene demonstrated that the Kayapo are infected with the HTLV-IIa subtype. Moreover, nucleotide sequence analysis of the LTR demonstrated that this belonged to a distinct HTLV-IIa phylogenetic group. The identification of HTLV-IIa in the Kayapo is, as far as we are aware, the first identified endemic focus of infection by this subtype of HTLV-II in the Americas.

Frequent detection of antibodies against HTLV antigens in patients with AIDS-related non-Hodgkin lymphoma

We studied the prevalence of anti-HTLV-I/II antibodies in 22 patients with AIDS-related non-Hodgkin lymphoma (NHL), 453 HIV-1-infected patients without lymphoma (194 of whom were diagnosed as having AIDS), and 6 HIV-1-positive and 75 HIV-1-negative patients with Hodgkin lymphoma. The frequency of serological reactivity against HTLV antigens was significantly higher in the AIDS patients with lymphoma than in those without (8 of 22, 36.4% vs. 20 of 194, 10.3%-p = 0.0027). One of the HIV-1-positive and none of the HIV-1-negative patients with Hodgkin lymphoma showed anti-HTLV-I/II reactivity. Four of the eight seropositive NHL patients showed antibodies directed against HTLV-II recombinant antigens when tested for serological discrimination in a Western blot assay. A PCR study of PBMCs from the only patient with NHL still alive at the time of the study showed HTLV-II-specific sequences in the genomic DNA. These data suggest that HTLV-II or a closely homologous retrovirus infects a high proportion of patients with AIDS-associated NHL.

Prevalence of human T-cell lymphotropic virus type 1 (HTLV-1) and HTLV-2 infection among Spanish drug users measured by HTLV-1 assay and HTLV-1 and -2 assay. HTLV-1 and HTLV-2 Spanish Study Group

The prevalence of human T-cell lymphotropic virus type 1 (HTLV-1) and HTLV-2 infection in 1992 and 1993 was determined by testing 2,152 specimens from injection drug users living in 11 geographic areas in Spain. Results obtained by an authentic HTLV-1 and -2 test were compared with those obtained by an HTLV-1 assay. HTLV infection was identified in 7 of 11 regions, with an overall prevalence of 2.5% (range, 0.4 to 11.5%). Fourty-four (81%) of 54 subjects were infected with HTLV-2; the viral strains in the remaining 10 subjects could not be serologically typed. Underestimation of HTLV infection because of the low sensitivities of HTLV-1 enzyme immunoassays for HTLV-2 antibody was relatively low (< 20%). Therefore, previous epidemiologic findings generated with HTLV-1 enzyme immunoassays appear to be reasonably accurate. Our results suggest that the rate of HTLV infection may have been increasing recently among Spanish drug users.

Evaluation of a combined lysate/recombinant antigen anti-HTLV-I/II ELISA in high and low endemic areas of HTLV-I/II infection

The Wellcozyme HTLV-I/II ELISA (Murex Diagnostics) was evaluated in 7800 samples of various serum panels. Repeat activity was found by Wellcozyme in (A) 1/2181 (0.05%) Dutch blood donors, (B) 44/3036 (1.4%) Curaçao (Caribbean area) blood donors, (C) 46/2533 (1.8%) individuals of different Ethiopian population subsets, (D) 30/30 (100%) confirmed anti-HTLV-I positive samples and (E) 20/20 (100%) HTLV-II PCR-positive samples. All 91 Wellcozyme-positive samples were tested for confirmation by Western blot (WB, Diagnostic Biotechnology). Among Wellcozyme HTLV-I/II ELISA-positive individuals, HTLV-I/II WB positivity was found in 0/1 Dutch blood donors, 40/44 (88.9%) Curaçao blood donors and 20/46 (43.5%) Ethiopian individuals. HTLV-I positivity was found in 40 (1.3%) WB-positive Curaçao blood donors and in 9 (0.35%) Ethiopian individuals. HTLV-II positivity was found in 11 (0.43%) WB-positive Ethiopian individuals. The Wellcozyme HTLV-I/II ELISA had a specificity of 99.95% in Dutch blood donors and a sensitivity of 100% on confirmed HTLV-I- and HTLV-II-positive samples. In Ethiopia 55% of the HTLV-I/II WB-positive individuals were exclusively HTLV-II positive, whereas in Curaçao no HTLV-II infections were found.

Incidence and risk factors for human T-lymphotropic virus type II seroconversion among injecting drug users in Baltimore, Maryland, U.S.A

To determine the incidence of and risk factors for human T-lymphotropic virus, type II (HTLV-II) seroconversion among injecting drug users (IDUs), specimens from IDUs recruited into the ALIVE Study in 1988/1989 were assayed at baseline for antibody to HTLV with use of enzyme immunoassay and Western blot. Participants were monitored semiannually with venipuncture and interviews. In 1992, the most recent sera of HTLV-negative participants were tested for HTLV with use of enzyme immunoassay and confirmed and typed by Western blot. For positive cases, assays were then performed for all intervening visits to determine the calendar time of seroconversion. Incidence rates were estimated using person-time. Risk factor analysis used a nested case-control design, with up to seven controls per case matched by time of study entry and duration of follow-up. At baseline, 251 HTLV-positive, 22 indeterminate, and 2,574 HTLV-seronegative IDUs were identified. Follow-up of the seronegative IDUs identified 38 seroconverters (all HTLV-II) over 5,813.6 person-years, for a rate of 0.7/100 person-years. Median lag time for seroconversion was 6.8 months. Factors associated with HTLV-II seroconversion included a specific needle-sharing practice called "backloading" within the previous 6 months [odds ratio (OR) = 6.52; 95% confidence interval (CI) = 1.94-21.95] and a baseline history of receiving money for sex (OR = 3.36; 95% CI = 1.32-8.57). Of those with more than one sex partner in the past 6 months, women were more likely than men to seroconvert (OR = 5.77; 95% CI = 1.33-25.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Presence of human T-lymphotropic virus type II-related genes in DNA of peripheral leukocytes from patients with autoimmune thyroid diseases

No etiologic role of human T-lymphotropic virus type II (HTLV-II) in any disease is yet known. The present study showed a high incidence of HTLV-II proviral DNA fragments in DNA of peripheral blood leukocytes from patients with autoimmune thyroid diseases. Using primers for the pol and tax regions of HTLV-II proviral DNA, amplified DNA fragments were demonstrated in 51.5% of the patients with Hashimoto's thyroiditis and in 11.8% of those with Graves' disease examined, but in only 1.9% of the disease controls and 1.0% of healthy individuals. These amplified DNA fragments hybridized with each of the inner probes. The nucleotide sequences of the DNA fragments of the pol and tax regions showed high homology with those of the prototype of HTLV-II. No antibodies for HTLV-II could, however, be detected in the patients examined. Because of the absence of its antibody, HTLV-II infection was not confirmed in these patients, but the presence of HTLV-II proviral DNA or its related DNA at high frequency suggests a relationship of HTLV-II with the development of autoimmune thyroid diseases.

Evidence for sexual and mother-to-child transmission of human T lymphotropic virus type II among Guaymi Indians, Panama

Guaymi Indians, a non-intravenous drug-using population in which human T cell lymphotropic virus type II (HTLV-II) is endemic, were studied in Changuinola, Panama, to identify the prevalence and modes of transmission of HTLV-II. A population-based survey showed that 352 (9.5%) of the 3686 participants were seropositive for HTLV-II. Infection rates were the same for male and female subjects and increased significantly with age, beginning in young adulthood. HTLV-II infection status was highly concordant among spouses (P < .001) and between mother and child; of children aged 1-10 years, 36 of 219 born to seropositive mothers were seropositive compared with 3 of 997 born to seronegative mothers (P < .001). The strong associations of HTLV-II infection with age and with an infected spouse in adults and of infection in children with infection in their mothers strongly suggest sexual and mother-to-child transmission of HTLV-II in this population.

Human T-lymphotropic virus type I and type II infections and correlation with risk factors in blood donors from São Paulo, Brazil

BACKGROUND

Little is known about the prevalence of and risk factors for human T-lymphotropic virus type I and type II (HTLV-I, HTLV-II) infections in Brazil.

STUDY DESIGN AND METHODS

Sera from 17,063 healthy Brazilian donors were screened by enzyme-linked immunosorbent assay for antibody to HTLV-I/II between August 1991 and July 1993. Repeatedly reactive samples were confirmed by Western blot, and discrimination between HTLV-I and HTLV-II was made by polymerase chain reaction or synthetic peptide enzyme-linked immunosorbent assay. A univariate analysis was performed on demographic and serologic data.

RESULTS

HTLV-I infection was demonstrated in 83 percent of the 30 donors with reactive serologic tests (0.15% of the total tested [17,063]; 95% CI, 0.09-0.20) and HTLV-II infection in 17 percent (0.03% of the total tested [17,063]; 95% CI, 0.01-0.05). HTLV-I-positive donors were more likely than reference groups to be of Asian ethnicity (odds ratio [OR] 15.1; reference group: whites), more than 50 years old (OR 4.2; reference group: 20-29 years old), and positive for antibody to hepatitis C virus (anti-HCV) (OR 21.8) or to hepatitis B core (antigen) (anti-HBc) (OR 5.7). HTLV-II showed a significant association with anti-HCV (OR 75.2) and anti-HBc (OR 21.8). Eleven of the 25 HTLV-I-positive donors were counseled. Family origin in endemic areas of Japan (n = 4), prior blood transfusion (n = 3), or sexual contact with prostitutes (n = 1) were the risk factors reported by 8 donors. In 3 white men, no risk factors could be identified.

CONCLUSION

Both HTLV-I and HTLV-II occur among Brazilian blood donors. HTLV-I is associated with Asian ethnicity, greater age, and the presence of anti-HCV and anti-HBc. Three HTLV-I-positive donors had a history of blood transfusion, which emphasizes the need for HTLV-I/II screening in Brazil.

Identification of HTLV-I- or HTLV-II-producing cells by cocultivation with BHK-21 cells stably transfected with a LTR-lacZ gene construct

The Syrian Hamster kidney cell line (BHK-21) was stably transfected with a plasmid vector containing the lacZ bacterial gene under the control of a HTLV-I-LTR promoter. In these cells termed pA18G-BHK-21, this lacZ construct is inducible by the tax protein produced by a tax expression vector. It was also shown that beta-galactosidase synthesis was detected within 48 h after cocultivation of pA18G-BHK-21 cells with HTLV-I (HUT-102, MT2, C91/PL, 2060) or HTLV-II (MoT strain) -producing cells. The number of positive cells was directly related to the number of HTLV-I or -II-infected cells seeded. In addition, the LTR transactivation observed in coculture with HTLV-I-infected cells was specifically inhibited by sera containing antibodies directed against HTLV-I proteins, but not, or only weakly, by sera containing HTLV-II antibodies. Conversely, beta-galactosidase expression induced by HTLV-II-infected cells was inhibited by sera of HTLV-II-infected individuals, but not, or only weakly, by HTLV-I-positive sera. Irrespective of the inducer cell, sera from uninfected people did not inhibit LTR-driven expression of the lacZ gene in pA18G-BHK-21 cells cocultivated with HTLV-producing cells. This assay may thus be employed profitably for the detection and quantification of both HTLV-producing cells and HTLV-specific antibodies.

Seroprevalence of anti-HTLV I/II and anti-HIV-1 antibodies in a sample population in the Marche Region, Italy

A total of 1292 sera, provided by different USLs (Local Health Centers) in the Marche Region (Italy), was tested by ELISA and Western Blot for the detection of anti-HTLV I/II ad HIV-1 antibodies. It was decided not to follow any particular criterion when collecting the sera, so no protocol of admission was established in advance. Of the 1292 sera tested, 12 were found antibody positive to HTLV I/II, 18 to HIV-1 and 4 to both viruses. Of the seropositives, for HTLV I/II and HIV-1, respectively, 2 and 3 were prisoners; 2 and 4 were IVDAs, 3 and 7 were hematological patients, 3 and 2 were hospitalized subjects (not for hematological disorders), and 2 and 2 were positives belonging to a healthy population group. These data suggest that the viruses may also be spreading among groups other than the high-risk ones (homosexuals, IVDAs, prisoners, blood-transfusion recipients, promiscuous heterosexuals).