Comparative evaluation of 14 immunoassays for detection of antibodies to the human T-lymphotropic virus types I and II using panels of sera from Sweden and West Africa

Evaluation of a fully automated high-throughput serology assay for detection of Hepatitis D virus antibodies

BACKGROUND

HDV antibody testing is recommended for universal screening and as the first line in an HDV double reflex testing strategy for effectively identifying patients with active infection for therapeutic treatments.

OBJECTIVE

The aim of this study is to evaluate the performance of a newly developed ARCHITECT HDV Total Ig (ARCHITECT HDV Ig) prototype assay.

STUDY DESIGN

Performance characteristics were determined for the ARCHITECT HDV Ig and a reference test, LIAISON XL Anti-HDV using a well-characterized specimen panel, comprising HDV RNA positive (n = 62) and negative (n = 70) samples, and healthy US blood donors.

RESULTS

Healthy US blood donors (n=200) showed 99.5% (199/200, 95%CI=97.65-99.98) specificity with ARCHITECT HDV Ig and 98.5 % (197/200, 95 %CI = 96.10-99.64) with LIAISON Anti-HDV. Among known HDV RNA positive samples, ARCHITECT HDV Ig detected 59/62 demonstrating 95.2 % sensitivity while LIAISON Anti-HDV sensitivity was 90.3 % (56/62). Among 101 HBV positive samples, 70 were reactive in the ARCHITECT test, 59 of which tested positive for HDV RNA for a positive predictive value (PPV) for the presence of HDV RNA was 84.3 %. For LIAISON Anti-HDV, 79 specimens were reactive and 56 contained HDV RNA: PPV for HDV RNA was 70.9 %. Among 70 HDV RNA negative samples, 39 were HBV positive. ARCHITECT HDV Ig negative predictive value (NPV) was 71.8 % and LIAISON Anti-HDV NPV was 41 % for the HBV positive group, respectively.

CONCLUSION

When compared to the LIASON Anti-HDV test, the ARCHITECT HDV Ig assay demonstrated enhanced sensitivity and specificity and better NPV and PPV values for HDV RNA status. The ARCHITECT HDV Ig assay represents a promising tool for universal screening of all HBsAg-positive persons.

Development and Validation of a Rapid Screening Test for HTLV-I IgG Antibodies

Initial diagnosis of human T cell lymphotropic virus (HTLV) infections is mainly based by detecting antibodies in plasma or serum using laboratory-based methods. The aim of this study was to develop and evaluate a rapid screening test for HTLV-I antibodies. Our rapid screening test uses HTLV-I p24 antigen conjugated to gold nanoparticles and an anti-human IgG antibody immobilized to a nitrocellulose strip to detect human HTLV-I p24-specific IgG antibodies via immunochromatography. Performance of the rapid screening test for HTLV-I was conducted on a total of 118 serum specimens collected in Salvador, Bahia, the epicenter for HTLV-1 infection in Brazil. Using a Western blot test as the comparator, 55 serum specimens were HTLV-I positive, 5 were HTLV-I and HTLV-II positive, and 58 were negative. The sensitivity of the rapid screening test for HTLV-1 was 96.7% and the specificity was 100%. The rapid screening test did not show cross-reaction with serum specimens from individuals with potentially interfering infections including those caused by HTLV-II, HIV-I, HIV-II, hepatitis A virus, hepatitis B virus, hepatitis C virus, herpes simplex virus, Epstein-Barr virus, SARS-CoV-2, Chlamydia trachomatis, Neisseria gonorrhoeae, Treponema pallidum, Toxoplasma gondii, and Plasmodium falciparum. The rapid screening test also did not show cross-reaction with potentially interfering substances. Strategies for HTLV diagnosis in non- and high-endemic areas can be improved with low-cost, rapid screening tests.

A New Flow Cytometry-Based Single Platform for Universal and Differential Serodiagnosis of HTLV-1/2 Infection

In the present work, we developed and evaluated the performance of a new flow cytometry-based single platform, referred to as “FC-Duplex IgG1 (HTLV-1/2)”, for universal and differential serodiagnosis of HTLV-1/2 infection. The proposed technology employs a system for detection of IgG1 antibodies in a single competitive immunofluorescence platform by flow cytometry using fluorescently labeled MT-2/MoT cell line mix coupled to a highly sensitive development system (Biotin/Streptavidin/Phycoerythrin). The stability of fluorescent labeling and the antigenicity of MT-2 and MoT cell lines were confirmed upon storage at −20°C for 2, 6, and 12 months. The anti-HTLV-1/2 IgG1 reactivity, expressed as percentage of positive fluorescent cells (PPFC), was evaluated for each target antigen along the titration curve of test serum samples (1:32 to 1:4,096). Upon selection of target cell line and serum dilutions with higher segregation score between groups, the performance of “FIX” and “FIX & PERM” protocols was evaluated. The “FIX” protocol presented excellent performance indices (Se = 92%/Sp = 94%/AUC = 0.96; Se = 96%/Sp = 100%/AUC = 0.99) for the universal (HTLV-1/2 vs. NI) and differential (HTLV-1 vs. HTLV-2) diagnosis of HTLV-1 infection, respectively. Optimization of the “FIX” protocol using the principle of synchronous and asynchronous pairwise analysis further improved the performance of “FC-Duplex IgG1 (HTLV-1/2)”, using the “FIX” protocol for differential diagnosis of HTLV-1 and HTLV-2 infections (Se = 100%/Sp = 100%/AUC = 1.00). In conclusion, the “FC-Duplex IgG1 (HTLV-1/2)” method represents an innovation in the biotechnology segment with the potential to compose a serological kit for differential diagnosis of HTLV-1/2 infection for reference laboratories and blood centers.

A Strategy for Screening and Confirmation of HTLV-1/2 Infections in Low-Endemic Areas

Serological tests have been widely used for detecting human T-cell lymphotropic virus type 1/2 (HTLV-1/2) antibodies in the endemic areas, but their performance in low-risk populations is rarely reported. The aim of this study was to evaluate the performance of four HTLV-1/2 screening assays and to discuss a strategy for diagnosis of HTLV-1/2 infection in a non-endemic area. At the present study, 1546 specimens repeatedly reactive (RR) by one screening ELISA were collected from blood centers/banks from January 2016 to April 2019. Avioq-ELISA, Murex-ELISA, Roche-ECLIA and Fujirebio-CLIA were independently performed on each plasma sample and compared to WB and LIA confirmatory tests. Positive or indeterminate specimens with blood available were quantified by qPCR. The results showed that 48 samples were finally confirmed as HTLV-1 positive, 13 were HTLV positive, 151 were indeterminate, and 387 were negative. All the WB-positive samples were also LIA-positive. Roche-ECLIA showed the highest sensitivity that was able to detect 91.8% positives and combined with the Murex-ELISA would significantly increase the positive detection rate (98.4%). In addition, LIA yield more indeterminate and HTLV-untyped results than WB (152 vs. 27), but was able to resolve infection status of some individuals with an indeterminate WB. Besides, 3 WB indeterminate and 1 LIA-untyped samples were confirmed as HTLV-1 positive by qPCR. Based on these findings, we put forward a proper test strategy for HTLV-1/2 diagnosis in low-prevalence areas. If possible, the Roche-ECLIA with the highest sensitivity is suggested as a second screening assay in primary labs. If not, all RR specimens are recommended to be firstly retested by Roche-ECLIA and Murex-ELISA in the reference lab. Secondly, samples reactive to any one of the two tests were quantified by qPCR, and then the NAT-negatives were furtherly submitted to LIA for confirmation. Thereby, the cost can be reduced and the diagnostic accuracy would be improved.

Evaluation of Elecsys HTLV-I/II assay in comparison with ARCHITECT rHTLV-I/II assay with Korean samples

BACKGROUND

The seroprevalence rate of human T-lymphotropic virus I and II (HTLV-I/II) in Korean blood donors has been known as 0.004%, and HTLV-I/II Ab screening test has been performed since 2008 in Korea. Korea Ministry of Food and Drug Safety (MFDS) approved two chemiluminescent microparticle immunoassays (CMIA) for testing HTLV-I/II antibody, ABBOTT PRISM HTLV-I/HTLV-II and ARCHITECT rHTLV-I/II. A multicenter performance evaluation study in Europe and Japan was carried out with the new electrochemiluminescence immunoassay (ECLIA) for HTLV-I/II antibody detection, Elecsys HTLV-I/II assay which launched in 2017, but not in Korea. We aimed to evaluate the clinical performance of Elecsys HTLV-I/II assay in comparison with ARCHITECT rHTLV-I/II for the detection of HTLV-I/II antibody with Korean samples.

METHODS

For sensitivity evaluation, 100 HTLV-I/II-positive Korean standards from Korean Red Cross and two HTLV-II-positive samples that were purchased from Seracure were used. For the specificity, 500 potential donor specimens from Korea University Hospital healthcare center were used. All the samples were simultaneously analyzed by the two HTLV-I/II assays, Elecsys HTLV-I/II assay and ARCHITECT rHTLV-I/II assay.

RESULTS

Elecsys HTLV-I/II assay and ARCHITECT rHTLV-I/II assay showed a complete agrement. Elecsys HTLV-I/II assay showed 100% sensitivity (95% CI: 96.38-100.0) and specificity (95% CI: 99.26-100.0).

CONCLUSIONS

Elecsys HTLV-I/II assay is as reliable as ARCHITECT rTHLV-I/II assay, and can be used as a screening test for HTLV-I/II in Korea.

Performance of Commercially Available Serological Screening Tests for Human T-Cell Lymphotropic Virus Infection in Brazil

Serological screening for human T-cell lymphotropic virus type 1 (HTLV-1) is usually performed using enzyme-linked immunosorbent assay (ELISA), particle agglutination, or chemiluminescence assay kits. Due to an antigen matrix improvement entailing the use of new HTLV antigens and changes in the format of HTLV screening tests, as well as newly introduced chemiluminescence assays (CLIAs), a systematic evaluation of the accuracy of currently available commercial tests is warranted. We aimed to assess the performance of commercially available screening tests for HTLV infection diagnosis. A diagnostic accuracy study was conducted on a panel of 397 plasma samples: 200 HTLV-negative plasma samples, 170 HTLV-positive plasma samples, and 27 plasma samples indeterminate by Western blotting (WB). WB-indeterminate samples (i.e., those yielding no specific bands for HTLV-1 and/or HTLV-2) were assessed by PCR, and the results were used to compare agreement among the commercially available ELISA screening tests. For performance analysis, WB-indeterminate samples were excluded, resulting in a final study panel of 370 samples. Three ELISA kits (Murex HTLV-1/2 [Murex], anti-HTLV-1/2 SYM Solution [SYM Solution], and Gold ELISA HTLV-1/2 [Gold ELISA]) and one CLIA kit (Architect rHTLV-1/2) were evaluated. All screening tests demonstrated 100% sensitivity. Concerning the HTLV-negative samples, the SYM Solution and Gold ELISA kits had specificity values of >99.5%, while the Architect rHTLV-1/2 test presented 98.1% specificity, followed by Murex, which had a specificity of 92.0%. Regarding the 27 samples with WB-indeterminate results, after PCR confirmation, all ELISA kits showed 100% sensitivity but low specificity. Accuracy findings were corroborated by the use of Cohen's kappa value, which evidenced slight and fair agreement between PCR analysis and ELISAs for HTLV infection diagnosis. Based on the data, we believe that all evaluated tests can be safely used for HTLV infection screening.

Evaluation of Sensitivity and Specificity Performance of Elecsys HTLV-I/II Assay in a Multicenter Study in Europe and Japan

Screening of blood for human T-cell lymphotropic virus type 1 and type 2 (HTLV-1 and -2, respectively) is important to diagnose and prevent infection and ensure the safety of blood supplies. The Elecsys HTLV-I/II assay is a newly developed, electrochemiluminescence screening assay for the detection of HTLV-1/2 infection. The sensitivity and specificity of the Elecsys HTLV-I/II assay were determined using well-characterized HTLV-1/2-positive serum and plasma samples and routine diagnostic and blood donor samples expected to be HTLV negative, respectively. These results were compared with those for at least one of the following CE-marked assays at seven independent laboratories and the Roche Diagnostics facility in Penzberg, Germany: Abbott Architect rHTLV-I/II, Ortho Avioq HTLV-I/II Microelisa system, Abbott Prism HTLV-I/HTLV-II, and DiaSorin Murex HTLV I+II. Fujirebio INNO-LIA HTLV-I/II Score was used as a confirmatory assay. The Elecsys HTLV-I/II, Abbott Architect rHTLV-I/II, and Abbott Prism HTLV-I/HTLV-II assays detected all HTLV-1/2-positive samples (sensitivity, 100%). Sensitivity for Ortho Avioq HTLV-I/II was 98.63%. The Elecsys HTLV-I/II assay had a specificity of 99.95% in blood donor samples, which was comparable to results for the other assays (range, 99.91 to 100%). In routine diagnostic samples, the specificity of the Elecsys HTLV-I/II assay was 99.83%, compared with 99.70% for Abbott Architect rHTLV-I/II. Specificity for the Elecsys HTLV-I/II assay in potentially cross-reactive samples was 100%, compared with 99.0% for Ortho Avioq HTLV-I/II and 99.2% for DiaSorin Murex HTLV I+II. The Elecsys HTLV-I/II assay has the sensitivity and specificity to support its use as a routine screening assay for detecting HTLV infection.

Serological and Molecular Methods to Study Epidemiological Aspects of Human T-Cell Lymphotropic Virus Type 1 Infection

We estimated that at least 5-10 million individuals are infected with HTLV-1. Importantly, this number is based on the study of nearly 1.5 billion people living in known human T-cell lymphotropic virus type 1 (HTLV-1) endemic areas, for which reliable epidemiological data are available. However, for some highly populated regions including India, the Maghreb, East Africa, and some regions of China, no consistent data are yet available which prevents a more accurate estimation. Thus, the number of HTLV-1 infected people in the world is probably much higher. The prevalence of HTLV-1 prevalence varies depending on age, sex, and economic level in most HTLV-1 endemic areas. HTLV-1 seroprevalence gradually increases with age, especially in women. HTLV-1 has a simian origin and was originally acquired by humans through interspecies transmission from STLV-1 infected monkeys in the Old World. Three main modes of HTLV-1 transmission have been described; (1) from mother-to-child after prolonged breast-feeding lasting more than six months, (2) through sexual intercourse, which mainly, but not exclusively, occurs from male to female and lastly, (3) from contaminated blood products, which contain HTLV-1 infected lymphocytes. In specific areas, such as Central Africa, zoonotic transmission from STLV-1 infected monkeys to humans is still ongoing.The diagnostic methods used to study the epidemiological aspects of HTLV-1 infection mainly consist of serological assays for the detection of antibodies specifically directed against different HTLV-1 antigens. Screening tests are usually based on enzyme-linked immunoabsorbent assay (ELISA), chemiluminescence enzyme-linked immunoassay (CLEIA) or particle agglutination (PA). Confirmatory tests include mostly Western blots (WB)s or innogenetics line immunoassay (INNO-LIA™) and to a lesser extent immunofluorescence assay (IFA). The search for integrated provirus in the DNA from peripheral blood cells can be performed by qualitative and/or quantitative polymerase chain reaction (qPCR). qPCR is widely used in most diagnostic laboratories and quantification of proviral DNA is useful for the diagnosis and follow-up of HTLV-1 associated diseases such as adult T-cell leukemia (ATL) and tropical spastic paraparesis/HTLV-1 associated myelopathy (TSP/HAM). PCR also provides amplicons for further sequence analysis to determine the HTLV-1 genotype present in the infected person. The use of new generation sequencing methodologies to molecularly characterize full and/or partial HTLV-1 genomic regions is increasing. HTLV-1 genotyping generates valuable molecular epidemiological data to better understand the evolutionary history of this virus.

The Changing Epidemiology of Human T-Cell Lymphotropic Virus Type 1 Infection in Peruvian Female Sex Workers, 1993-2010

Human T-cell lymphotropic virus type 1 (HTLV-1) was the first human retrovirus to be reported and is associated with neoplastic, neurological, autoimmune, and infectious complications. HTLV-1 is endemic in Peru, with the highest prevalence reported among commercial sex workers. Seroprevalence data collected from Peruvian female sex workers (FSWs) working in Callao over three study periods between 1993 and 2010 were used to examine the secular trend in HTLV-1 prevalence. Between 1993 and 2010, the prevalence of HTLV-1 decreased significantly from 14.5% to 3.1% (P < 0.01). The prevalence of HTLV-1 seropositivity differed significantly by birth cohort (1922-1959, 1960-1969, 1970-1979, and 1980-1992), and for each of the four birth cohorts, the prevalence did not significantly decrease by screening year (P > 0.07). There were no cases of HTLV-1 detected among FSW born after 1979 (N = 224). Participant characteristics associated with HTLV-1 seropositivity were birth in the Andes Mountains region, age, increased time in sex work, younger age of starting sex work, and human immunodeficiency virus (HIV) seropositivity. The secular trend in declining prevalence persisted after adjustment for age, time in sex work, place of birth, and HIV serostatus, with the odds of HTLV-1 infection decreasing approximately 16% per year (adjusted odds ratio = 0.84, 95% confidence interval = 0.78, 0.90). The increasing use of condoms by later birth cohorts noted in our analysis, as well as the increasing availability of free condoms provided by the Peruvian government-which started in the late 1980s before this study-may have been responsible for declining HTLV seroprevalence.

A new and frequent human T-cell leukemia virus indeterminate Western blot pattern: epidemiological determinants and PCR results in central African inhabitants

Human T-cell leukemia virus (HTLV) indeterminate Western blot (WB) serological patterns are frequently observed in plasma/serum from persons living in intertropical areas. In the framework of ongoing projects on HTLV-1/2 and related viruses in Central Africa, we systematically analyzed plasma from villagers living in South Cameroon by WB. The group included 1,968 individuals (mean age, 44 years; age range, 5 to 90 years; 978 women/990 men), both Bantus (1,165) and Pygmies (803). Plasma samples were tested by WB analysis (MPD HTLV Blot 2.4) and interpreted according to the manufacturer's instructions. Only clear bands were considered in the analysis. Among the 1,968 plasma samples, 38 (1.93%) were HTLV-1, 13 (0.66%) were HTLV-2, and 6 (0.3%) were HTLV WB seropositive. Furthermore, 1,292 (65.65%) samples were WB sero-indeterminate, including 104 (5.28%) with an HTLV-1 Gag-indeterminate pattern (HGIP) and 68 (3.45%) with a peculiar yet unreported pattern exhibiting mostly a strong shifted GD21 and a p28. The other 619 (31.45%) samples were either WB negative or exhibited other patterns, mostly with unique p19 or p24 bands. DNA, extracted from peripheral blood buffy coat, was subjected to PCR using several primer pairs known to detect HTLV-1/2/3/4. Most DNAs from HTLV-1- and HTLV-seropositive individuals were PCR positive. In contrast, all the others, from persons with HTLV-2, HGIP, new WB, and other indeterminate patterns, were PCR negative. Epidemiological determinant analysis of the persons with this new peculiar WB pattern revealed that seroprevalence was independent from age, sex, or ethnicity, thus resembling the indeterminate profile HGIP rather than HTLV-1. Moreover, this new pattern persists over time.

Characterization of antibodies elicited by XMRV infection and development of immunoassays useful for epidemiologic studies

Background

Xenotropic Murine Leukemia Virus-related Virus (XMRV) is a human gammaretrovirus recently identified in prostate cancer tissue and in lymphocytes of patients with chronic fatigue syndrome. To establish the etiologic role of XMRV infection in human disease requires large scale epidemiologic studies. Development of assays to detect XMRV-specific antibodies would greatly facilitate such studies. However, the nature and kinetics of the antibody response to XMRV infection have yet to be determined.

Results

Three rhesus macaques were infected with XMRV to determine the dynamics of the antibody responses elicited by infection with XMRV. All macaques developed antibodies to XMRV during the second week of infection, and the predominant responses were to the envelope protein gp70, transmembrane protein p15E, and capsid protein p30. In general, antibody responses to gp70 and p15E appeared early with higher titers than to p30, especially in the early period of seroconversion. Antibodies to gp70, p15E and p30 persisted to 158 days and were substantially boosted by re-infection, thus, were identified as useful serologic markers. Three high-throughput prototype assays were developed using recombinant proteins to detect antibodies to these viral proteins. Both gp70 and p15E prototype assays demonstrated 100% sensitivity by detecting all Western blot (WB) positive serial bleeds from the XMRV-infected macaques and good specificity (99.5-99.9%) with blood donors. Seroconversion sensitivity and specificity of the p30 prototype assay were 92% and 99.4% respectively.

Conclusions

This study provides the first demonstration of seroconversion patterns elicited by XMRV infection. The nature and kinetics of antibody responses to XMRV in primates were fully characterized. Moreover, key serologic markers useful for detection of XMRV infection were identified. Three prototype immunoassays were developed to detect XMRV-specific antibodies. These assays demonstrated good sensitivity and specificity; thus, they will facilitate large scale epidemiologic studies of XMRV infection in humans.

Evaluation of the use of real-time PCR for human T cell lymphotropic virus 1 and 2 as a confirmatory test in screening for blood donors

INTRODUCTION: HTLV-1/2 screening among blood donors commonly utilizes an enzyme-linked immunosorbent assay (EIA), followed by a confirmatory method such as Western blot (WB) if the EIA is positive. However, this algorithm yields a high rate of inconclusive results, and is expensive. METHODS: Two qualitative real-time PCR assays were developed to detect HTLV-1 and 2, and a total of 318 samples were tested (152 blood donors, 108 asymptomatic carriers, 26 HAM/TSP patients and 30 seronegative individuals). RESULTS: The sensitivity and specificity of PCR in comparison with WB results were 99.4% and 98.5%, respectively. PCR tests were more efficient for identifying the virus type, detecting HTLV-2 infection and defining inconclusive cases. CONCLUSIONS: Because real-time PCR is sensitive and practical and costs much less than WB, this technique can be used as a confirmatory test for HTLV in blood banks, as a replacement for WB.

Evaluation of a new third-generation ARCHITECT rHTLV-I/II assay for blood screening and diagnosis

In comparison to current on-market assays, the ARCHITECT rHTLV-I/II assay is the first fully automated assay that simultaneously detects human T-cell lymphotropic virus type I (HTLV-I) and type II (HTLV-II) in human serum and plasma. Specificity was assessed on 5646 blood donors and 692 clinical specimens. For sensitivity determination, 301 HTLV-I-positive and 105 HTLV-II-positive specimens were tested. Precision was between 3.98% and 4.31% coefficient of variation (CV) for specimens with 1 to 6 sample to cutoff. Specificity was 99.95% and 99.86% on specimens from blood donors and hospitalized patients, respectively. Sensitivity evaluation showed 100% detection on 301 HTLV-I and 105 HTLV-II specimens. HTLV-I and HTLV-II viruses are still circulating among general populations even in the low prevalence areas. To control the further spread of these retroviruses, we need to know that it is important to continue screening of blood. The performance evaluation data from this study demonstrate that the high throughput and fully automated ARCHITECT rHTLV-I/II chemiluminescence immunoassay effectively serves this purpose.

Status of blood banking and the blood supply in Afghanistan

BACKGROUND

As a result of more than 20 years of war in Afghanistan, its blood supply system has been damaged. We carried out an assessment of that blood supply system to determine the type and extent of assistance needed to increase blood availability and safety.

STUDY DESIGN AND METHODS

An assessment tool was developed, daily activities in Afghanistan were observed, and key personnel were interviewed.

RESULTS

Because there was no donor recruitment organization, most blood was obtained by the family replacement system. There was an inadequate supply of stored blood, which led to use of blood before screening test results for transfusion-transmitted disease were complete. Whole blood was provided but blood components were not produced. Blood was tested intermittently for human immunodeficiency virus Types 1 and 2, hepatitis B surface antigen, hepatitis C virus, and syphilis using agglutination-based screening methods.

CONCLUSIONS

A dedicated staff is in place but to strengthen the blood supply system in Afghanistan, it will be important to address infrastructure and facilities, organization, standard operating methods, supplies and equipment, training, quality assurance, and transfusion medicine education.

Evaluation of a new, fully automated immunoassay for detection of HTLV-I and HTLV-II antibodies

Screening blood donations for human T-lymphotropic virus types I and II (HTLV-I/II) continues to be important in protecting the safety of blood products and controlling the global spread of these retroviruses. We have developed a fully automated, third generation chemiluminescent immunoassay, ARCHITECT rHTLV-I/II, for detection of antibodies to HTLV-I/II. The assay utilizes recombinant proteins and synthetic peptides and is configured in a double antigen sandwich assay format. Specificity of the assay was 99.98% (9,254/9,256, 95% CI = 99.92-100%) with the negative specimens from the general population including blood donors, hospital patients and pregnant women from the US, Japan and Nicaragua. The assay demonstrated 100% sensitivity by detecting 498 specimens from individuals infected with HTLV-I (n = 385) and HTLV-II (n = 113). ARCHITECT rHTLV-I/II results were in complete agreement with the Murex HTLV-I/II reference assay and 99.7% agreement with the Genelabs HTLV Blot 2.4 confirmatory assay. Analytical sensitivity of the assay was equivalent to Murex HTLV-I/II assay based on end point dilutions. Furthermore, using a panel of 397 specimens from Japan, the ARCHITECT rHTLV-I/II assay exhibited distinct discrimination between the antibody negative (Delta Value = -7.6) and positive (Delta Value = 7.6) populations. Based on the excellent specificity and sensitivity, the new ARCHITECT rHTLV-I/II assay should be an effective test for the diagnosis of HTLV-I/II infection and also for blood donor screening.

Difficulties in the diagnosis of HTLV-2 infection in HIV/AIDS patients from Brazil: comparative performances of serologic and molecular assays, and detection of HTLV-2b subtype

The current diagnosis of human T-lymphotropic virus type-2 (HTLV-2) infection is based on the search of specific antibodies; nevertheless, several studies conducted in Brazil pointed deficiencies of the commercially available kits in detecting HTLV-2, mostly in HIV/AIDS patients. This study searched for the presence of HTLV-1 and -2 in 758 HIV/AIDS patients from Londrina, Paraná, Brazil. Serum samples were screened for HTLV-1/2 antibodies using two EIA kits (Vironostika and Murex), and confirmed by WB (HTLV Blot 2.4, Genelabs). The results obtained by EIA disclosed 49 (6.5%) reactive sera: 43 positive by both EIA kits, and six with discordant results. WB confirmed HTLV-1 infection in seven samples (0.9%) and HTLV-2 in 21 sera (2.8%). Negative and indeterminate results were detected in four (0.5%) and 16 (2.1%) sera, respectively. Blood from 47 out of 49 HTLV seroreactive patients were collected and analyzed for the presence of env, LTR and tax genomic segments of HTLVs by PCR. PCR confirmed six cases of HTLV-1 and 37 cases of HTLV-2 infection (14 out of 16 that were found to be WB indeterminate). Restriction analysis of the env PCR products of HTLV-2 disclosed 36 isolates of HTLV-2a/c subtype, and one of HTLV-2b subtype. These results emphasize the need of improving serologic tests for detecting truly HTLV-2 infected patients from Brazil, and confirm the presence of HTLV-2b subtype in the South of this country.

[Cloning and expression of the transmembranic glycoprotein from human T cell lymphotropic virus in a prokaryotic system]

HTLV-1 is the virus that causes T cell lymphoma/leukemia in adults and a neurological disorder known as HTLV-associated myelopathy or tropical spastic paraparesis. One of the transmission means is through contaminated blood and its byproducts. Because of the risk of HTLV-associated infections, screening for HTLV was introduced for Brazilian blood donors in 1993. Most of the diagnostic kits used in the national blood banks are bought from foreign companies. Brazil does not have the technology to produce this material and there is a need to produce diagnostic systems with national technology. In this study, we show the expression of gp21/HTLV-1 in Escherichia coli and its reactivity towards monoclonal antibodies and the antibodies of infected patients. Expressing these proteins is the first step towards obtaining diagnostic kits with Brazilian biotechnology.

False-reactive microbiologic screening test results in Swedish blood donors?how big is the problem? A survey among blood centers and deferred donors

BACKGROUND

Screening of blood donors for markers of transfusion-transmissible infectious agents leads to a varying number of false-reactive test results and sometimes thereby temporary or permanent deferral of donors and also to loss of collected units.

STUDY DESIGN AND METHODS

Data on false-reactive screening test results in 2002 and 2003 were collected from 19 blood centers in Sweden. A questionnaire was sent to donors deferred because of false-reactive screening test results to investigate their perception of the information and their reaction to the deferral.

RESULTS

Testing of 21,189 samples from new donors and 423,543 donations from regular and/or repeat donors produced 1,059 false-reactive test results, mostly from hepatitis C virus antibody testing, and 299 deferrals. Six different human immunodeficiency virus tests led to between 0.02 and 0.2 percent false-reactive results. The deferral rate varied considerably between different counties. Of 204 deferred donors contacted, 180 (88%) answered the questionnaire. More than 80 percent were worried about their test results and worry was more common among those who did not feel sufficiently informed.

CONCLUSION

The results imply that there is a need for a more standardized approach to the screening of blood donors and donations with the aim of minimizing the number of false-reactive screening test results. They also emphasize the importance of appropriate information and support to deferred donors.

Molecular characterization of human T-cell lymphotropic virus type 2 (HTLV-II) from people living in urban areas of Sao Paulo city: Evidence of multiple subtypes circulation

BACKGROUND

In Brazil, human T-cell lymphotropic virus type I and type II (HTLV-I and HTLV-II) are co-circulating and possess approximately 65% homology, which results in high cross-reactivity in serological tests. Based on the detection of EIA and Western blot (WB) tests, HTLV serodiagnosis yields indeterminate results in high-risk population, with the true determination of HTLV-II prevalence requiring a combined serological and molecular analysis. Molecular analysis of HTLV-II isolates has shown the existence of four distinct subtypes: IIa, IIb, IIc, and IId. The aim of this study was to evaluate the routine EIA and WB used in Sao Paulo city, as well as molecular methods for confirmation of infection and HTLV-II subtype distribution.

RESULTS

Two hundred ninety-three individuals, who were enrolled in the HTLV out-clinic in Sao Paulo city, Brazil, between July 1997 and May 2003, were tested by EIAs, and positive sera 232 (79%) reactive by one of the tests. When these sera were tested by WB revealed 134 were HTLV-I, 28 HTLV-II, 4 HTLV-I/II, and 48 were indeterminate. Polymerase chain reaction (PCR) on the indeterminate group showed that 20 (42%) were HTLV-II and 28 were negative. From a total of 48 HTLV-II subjects with DNA available, restriction fragment length polymorphism (RFLP) of the env region revealed 47 HTLV-IIa and 1 HTLV-IIb. The phylogenetic analysis was performed on 23 samples, which identified 19 as subtype a, Brazilian subcluster, and 4 as subtype b. This is the first time HTLV-II subtype b has been described in Brazil. However, further studies, such as a complete nucleotide DNA sequencing, need to be done to confirm these findings.

Increased prevalence of HTLV-1 among HIV-2-infected women but not HIV-2-infected men in rural Guinea-Bissau

OBJECTIVE

To assess the prevalence of HTLV infection and its association with HIV and other potential risk factors.

DESIGN AND SETTING

A cross-sectional survey and a case-control study in a rural community in Guinea-Bissau.

METHODS

A total of 2770 people were included in an HIV and HTLV seroepidemiologic survey. Three hundred of these participants were selected for a case-control study on HIV-2. Sera from both studies were tested for HTLV.

RESULTS

In all, 2501 and 298 subjects in the survey and case-control study, respectively, were tested for HTLV. Overall HTLV-1 prevalence was 5.2% and it was higher in women (odds ratio [OR], 1.36; confidence interval [CI], 0.92-2.02). Apart from an infected spouse, no significant risk factors could be identified for men. In women, HIV-2 infection (adjusted OR, 5.58; CI, 3.09-10.1), having an infected spouse, and area of residence were significantly associated with HTLV-1 infection. The association between HTLV-1 and HIV-2 was significantly different for men and women (test of interaction, p =.002).

CONCLUSIONS

In women, the most important determinant of HTLV-1 seropositivity was HIV-2 infection. Because the pattern was significantly different for men and women, common sexual risk factors may not be sufficient to explain the co-occurrence of HIV-2 and HTLV-1 in women. These observations may have implications in geographic areas where both types of retroviruses are prevalent.

Strategies for diagnosis of HTLV-I and -II

BACKGROUND

No gold standard exists for diagnosis of HTLV infection. The aim of thus study was to compare the accuracy of a combination of two sensitive ELISAs with Western blot (WB), a line immunoassay, and PCR for diagnosis of HTLV infection.

STUDY DESIGN AND METHODS

Nine hundred eighty-five specimens were tested for the presence of HTLV antibodies by HTLV-I and/or HTLV-II EIAs (Murex and Ortho), WB (Diagnostic Biotechnology), line immunoassay (INNO-LIA, Innogenetics), and/or presence of HTLV DNA by PCR. The results were compared with the probable HTLV infection status of each subject, as determined by detailed review of all available laboratory, clinical, and epidemiologic data.

RESULTS

The sensitivity for diagnosis of HTLV-I infection was high for all assays evaluated, but both PCR and WB had a lower sensitivity rate (approx., 80%) for confirmation of HTLV-II. INNO-LIA detected 94 percent of the HTLV-II-positive samples. However, Murex EIA in combination with Ortho EIA was 100-percent sensitive for the detection of both HTLV-I and HTLV-II antibodies. Furthermore, the number of samples giving indeterminate results in the ELISA combination was much lower as compared with WB (2.5% vs. 50%).

CONCLUSION

Based on these findings, a new, more sensitive and specific test strategy for HTLV diagnosis than the current algorithm, which includes WB, is proposed. Thereby, both the direct and indirect costs can be substantially reduced.

Pooling of samples for seroepidemiological surveillance of human T-cell lymphotropic virus types I and II

We evaluated a straight forward pooling strategy for antibody screening of HTLV-I/II, using panels of sera from various parts of the world including a total of 43 HTLV-I and 54 HTLV-II positive specimens. Four antibody screening assays were included in the evaluation: the HTLV-I/II GE 80/81 (Murex Diagnostics), the HTLV-I/HTLV-II Ab Capture ELISA (Ortho Diagnostics), the HTLV-I/II ELISA 3.0 (Genelabs Diagnostics) and the Serodia HTLV-I (Fujirebio). The Murex and Ortho assays represent a new generation of HTLV screening tests with a sandwich format incorporating both HTLV-I and HTLV-II synthetic and/or recombinant peptide antigens. The Genelabs assay is an indirect ELISA with recombinant HTLV-I and -II antigens and Serodia is a particle agglutination assay with HTLV-I whole viral lysate. Each HTLV-positive sample was included in pools of 1/1 up to 1/16, in two-fold steps made in normal HTLV-negative blood donor serum from one up to nine donors. For HTLV-I, with the exception of one false negative sample in dilution 1/16 with Genelabs ELISA, all assays were positive at all dilutions. The Murex assay had absorbance values at maximum levels for all samples at all dilutions. The other assays had gradually decreasing absorbance values although clearly above cut-off. For HTLV-II, the Murex assay correctly detected all samples to dilution 1/16 despite gradually decreasing signals. The Serodia assay had 100% sensitivity to dilution 1/4 while at 1/8 and 1/16 it decreased 82 and 80%, respectively. The Genelabs ELISA had gradually decreasing sensitivity for HTLV-II from 98 (1/1) to 33% (1/16) while the Ortho assay detected all specimens at all dilutions in a limited set of samples tested. Taken together, this evaluation has shown that pooling of samples may be an appropriate strategy for serosurveillance of HTLV. It is, however, crucial to limit the number of samples and to choose assays that allow the dilution caused by the pooling. Using the best performing assays in this evaluation for pools of e.g. five samples would leave a reasonable safety margin.

Human T cell leukaemia/lymphoma virus infection in pregnant women in the United Kingdom: population study

OBJECTIVE

To assess the prevalence of human T cell leukaemia/lymphoma virus (HTLV) infection in pregnant women in the United Kingdom.

DESIGN

Population study.

SUBJECTS

Guthrie card samples from babies born in 1997-8. Samples were linked to data on mother's age and ethnic status and parents' country of birth and then anonymised.

SETTING

North Thames Regional Health Authority.

MAIN OUTCOME MEASURES

Presence of antibodies against HTLV in eluates tested by gelatin particle agglutination assay and results confirmed by immunoblot.

RESULTS

Of 126 010 samples tested, 67 had confirmed antibodies to HTLV (59 HTLV-I, 2 HTLV-II, 6 untyped) and six had indeterminate results. Seroprevalence was 17.0 per 1000 (95% confidence interval 9.2 to 28.3) in infants whose mothers were born in the Caribbean, 3.2/1000 (1.5 to 5.9) with mothers born in west and central Africa, and 6.8/1000 (3.1 to 12.9) in infants of black Caribbean mothers born in non-endemic regions. In infants with no known risk (both parents born in non-endemic regions and mother not black Caribbean) seroprevalence was 0.06-0.12 per 1000. Mother's country of birth, father's country of birth, and mother's ethnic status were all independently associated with neonatal seroprevalence. An estimated 223 (95% confidence interval 110 to 350) of the 720 000 pregnant women each year in the United Kingdom are infected with HTLV.

CONCLUSIONS

The prevalence of HTLV and HIV infections in pregnant women in the United Kingdom are comparable. The cost effectiveness of antenatal HTLV screening should be evaluated, and screening of blood donations should be considered.