Comparative performances of an HTLV-I/II EIA and other serologic and PCR assays on samples from persons at risk for HTLV-II infection

BACKGROUND: HTLV-I and HTLV-II are related exogenous pathogenic human retroviruses. Until recently, ELISAs based on HTLV-I antigens have been used to screen for the presence of HTLV-I or -II antibodies. The HTLV-I-based assays have not been as sensitive in detecting antibodies to HTLV-II as in detecting antibodies to HTLV-I. The Abbott HTLV-I/HTLV-II ELISA uses a combination of HTLV-I and HTLV-II antigens to detect antibodies to the whole HTLV group. The performance of this ELISA was compared to that of several HTLV-I-based serologic assays and an HTLV-II PCR assay in cohorts of South American Indians and New York City IV drug users (IVDUs) in whom HTLV-II is endemic. STUDY DESIGN AND METHODS: Sera from 429 South American Indians and New York City IVDUs were evaluated for HTLV antibodies by the use of three ELISAs (rgp21-enhanced HTLV-I/II, Cambridge Biotech; Vironostika HTLV-I/II, Organon Teknika; and HTLV-I/HTLV-II, Abbott), and a Western blot (WB) assay. Peripheral blood leukocyte DNA from each person was analyzed for HTLV-I and HTLV-II pol DNA via PCR. The HTLV-II PCR-positive samples were further subtyped via cloning and sequencing and/or oligomer restriction. RESULTS: Two hundred four samples (48%) were positive for HTLV-II by serologic and/or PCR assays. All of the positive samples from the Indians and approximately one-third of the positive samples from the IVDUs were of the HTLV-IIB subtype. Comparative analyses indicate that the sensitivity and specificity of the various assays were: PCR, 98 and 100 percent; Abbott HTLV-I/HTLV-II, 78 and 95 percent; Cambridge Biotech HTLV-I/II, 76 and 96 percent; Vironostika HTLV-I/II, 71 and 98 percent; and WB, 73 and 100 percent, respectively. CONCLUSION: There were no significant differences among the sensitivities and specificities of the HTLV-I/II ELISAs (p values, 0.056-0.438). The WB and PCR assays were much more specific than the other serologic assays (p相似文献   

Sensitivity of Two Enzyme-linked Immunosorbent Assay Tests in Relation to Western Blot in Detecting Human T-Cell Lymphotropic Virus Types I and II Infection among HIV-1 Infected Patients from São Paulo,Brazil

We investigated the presence of human T-cell lymphotropic virus types I and II (HTLV-I and HTLV-II) infections, first searching for specific antibodies in 553 serum samples obtained from HIV-1-infected patients from São Paulo, Brazil. Sera were screened using two enzyme-linked immunosorbent assays (ELISAs): the ELISA-EM (ELISA HTLV-I/II, EMBRABIO, BR), which contains HTLV-I and HTLV-II lysates, and the ELISA-DB [ELISA HTLV-I/II, Diagnostic Biotechnology (DB), Singapore], which contains HTLV-I lysate, and HTLV-I and HTLV-II recombinant env proteins (MTA-1 and K55, respectively). Serum samples showing two positive and/or borderline results were confirmed by Western blot (WB 2.3, DB), which discriminates HTLV-I from HTLV-II. WB analyses disclosed 22 cases (4.0%) of HTLV-I and 34 (6.1%) of HTLV-II seroreactivity; 24 sera had indeterminate antibody profile (4.3%) and 2 specimens showed reactivity to both MTA-1 and K55 env proteins. Using stringent WB criteria and analyzing the population according to risk factors, the prevalence rates of HTLV-I and HTLV-II infections were 11.2% and 16.8% in IV drug users, 3.4% and 5.5% in heterosexual individuals, and 1.4% and 2.2% in homosexual/bisexual men, respectively. A comparison of ELISA and WB results disclosed that both ELISAs were highly sensitive in detecting HTLV-I antibodies, whereas the ELISA-DB showed 82% sensitivity and the ELISA-EM 100% sensitivity in detecting HTLV-II antibodies. PCR analyses conducted on 37 representative cells samples confirmed the presence of HTLV proviral DNA in the majority of concordant serological cases, except in one, which was HTLV-I infected and seroreacted with K55 protein of HTLV-II. Indeed, after PCR, one case of HTLV-I infection and HTLV-II coinfection, and 30% of WB-seroindeterminate or inconclusive cases infected with HTLV-II could be detected. Our data stress high prevalences of both HTLV-I and HTLV-II infections in HIV-1 coinfected i.v. drug users from São Paulo, and suggests that ELISA kits containing only K55 protein as the HTLV-II-specific antigen, may not have the appropriate sensitivity for the detection of HTLV-II infection in this geographic region, pointing out the need of improved screening tests to be used in Brazil.     

Sensitivity and specificity of human T-lymphotropic virus (HTLV) types I and II polymerase chain reaction and several serologic assays in screening a population with a high prevalence of HTLV-II

BACKGROUND: Since 1988, all blood donations in the United States have been screened for antibodies to human T-lymphotropic virus type I (HTLV-I). However, the sensitivity of current serologic tests for the detection of HTLV type II (HTLV-II) antibodies and the diagnostic utility of direct tests for HTLV-I and -II using polymerase chain reaction (PCR) are poorly defined. STUDY DESIGN AND METHODS: Five hundred sixty-nine HTLV-I- or -II-seropositive and 687 age- and sex-matched seronegative samples from a high-risk population at an inner-city emergency department were selected. All samples were tested with four HTLV enzyme immunoassays (EIAs), one Western blot assay and one type-specific Western blot assay, one HTLV type-specific EIA, and a research HTLV-I/II PCR kit. RESULTS: Sensitivity of the various EIAs ranged from 95.1 to 99.5 percent, and specificity ranged from 97.2 to 99.4 percent. PCR performed in duplicate without selective retesting had lower sensitivity (85.1 %) and specificity (88.0%). However, PCR detected 20 (3.2%) HTLV-I-positive and 47 (7.5%) HTLV-II-positive samples among the 627 samples that were negative in all EIAs. The type-specific EIA and PCR assay had the highest rate of concordance in classifying samples as either HTLV-I or II, with the type-specific EIA and type-specific Western blot having the next highest rates of concordance. CONCLUSION: In this sample set from a population at high risk for HTLV-II, screening with HTLV-I/II PCR had lower sensitivity and specificity than that with EIAs. However, 4.1 to 10.8 percent of samples were PCR positive but seronegative for HTLV-I or -II, and their true infection status remains undetermined.     

Sensitivity and specificity of human T-lymphotropic virus (HTLV) types I and II polymerase chain reaction and several serologic assays in screening a population with a high prevalence of HTLV-II

BACKGROUND: Since 1988, all blood donations in the United States have been screened for antibodies to human T-lymphotropic virus type I (HTLV-I). However, the sensitivity of current serologic tests for the detection of HTLV type II (HTLV-II) antibodies and the diagnostic utility of direct tests for HTLV-I and -II using polymerase chain reaction (PCR) are poorly defined.
STUDY DESIGN AND METHODS: Five hundred sixty-nine HTLV-I- or -II-seropositive and 687 age- and sex-matched seronegative samples from a high-risk population at an inner-city emergency department were selected. All samples were tested with four HTLV enzyme immunoassays (EIAs), one Western blot assay and one type-specific Western blot assay, one HTLV type-specific EIA, and a research HTLV-I/II PCR kit.
RESULTS: Sensitivity of the various EIAs ranged from 95.1 to 99.5 percent, and specificity ranged from 97.2 to 99.4 percent. PCR performed in duplicate without selective retesting had lower sensitivity (85.1%) and specificity (88.0%). However, PCR detected 20 (3.2%) HTLV-I-positive and 47 (7.5%) HTLV-II-positive samples among the 627 samples that were negative in all EIAs. The type-specific EIA and PCR assay had the highest rate of concordance in classifying samples as either HTLV-I or -II, with the type-specific EIA and type-specific Western blot having the next highest rates of concordance.
CONCLUSION: In this sample set from a population at high risk for HTLV-II, screening with HTLV-I/II PCR had lower sensitivity and specificity than that with EIAs. However, 4.1 to 10.8 percent of samples were PCR positive but seronegative for HTLV-I or –II, and their true infection status remains undetermined.     

Comparative performances of enzyme-linked immunosorbent, western blot, and polymerase chain reaction assays for human T-lymphotropic virus type II infection that is endemic among Indians of the Gran Chaco region of South America

BACKGROUND : Human T-cell lymphoma/leukemia viruses types I and II (HTLV- I and HTLV-II) are related exogenous human retroviruses. The former is definitely pathogenic while disease association with the latter is unclear. There are two subtypes of HTLV-II, A and B. Currently, enzyme- linked immunosorbent assays (ELISAs) based on HTLV-I antigens are used to screen for the presence of HTLV-I and -II antibodies. Confirmation and subtyping are accomplished by Western blot (WB) or ELISAs based on HTLV-I whole viral antigens and/or HTLV-I and HTLV-IIA peptides. The sensitivity and specificity of these serologic assays were compared to those of HTLV-I and-II-specific polymerase chain reaction (PCR) assays in tests on samples from Indians from South America in whom the HTLV- IIB subtype is endemic. STUDY DESIGN AND METHODS : Sera from 246 Gran Chaco Indians were evaluated for HTLV antibodies with the use of four ELISAs (Retrotek HTLV-I; Cambridge Biotech rgp21 enhanced HTLV-I/II; Vironostika HTLV-I/II; and Select HTLV-I/II), and a WB assay. Peripheral blood leukocyte DNA from each Indian was analyzed for HTLV-I or HTLV-II pol DNA via PCR. Fifteen of the PCR-positive samples were further subtyped via cloning and sequencing and/or oligomer restriction. RESULTS : Ninety-seven samples (39%) were positive for HTLV- II by serologic and/or PCR assays. All 15 positive DNA samples that were further analyzed were of the HTLV-IIB subtype and were clustered as a highly conserved phylogenetic group. Comparative analyses indicate that the sensitivity and specificity of the various assays were: PCR, 97 and 100 percent; Retrotek, 70 and 91 percent; Cambridge Biotech, 74 and 96 percent; Vironostika, 73 and 99 percent; Select 72 and 98 percent; and WB, 70 and 100 percent. CONCLUSION : The sensitivities of the tested HTLV serologic assays were comparable. However, the specificity of the Retrotek ELISA was significantly lower than that of the others. When positive, the subtyping assays were very specific. However, PCR assays would seem preferable or to be a necessary adjunct for the sensitive detection of HTLV-IIB infection.     

Serologic distinction between human T-lymphotropic virus (HTLV) type I and HTLV type II

In November 1988, the Food and Drug Administration approved reagents for serologic screening for human T-lymphotropic virus type I (HTLV-I) infection in blood donors and patients suspected of having HTLV-I-related illnesses. These reagents are able to detect HTLV type II (HTLV-II), a close relative of HTLV-I with no known pathologic effect. The distinction between the two forms of HTLV is important to the donor and to any recipient of blood containing HTLV. The application to sera from 38 seropositive blood donors and 2 recipients (37 "confirmed" positive and 3 indeterminate by Western blot) of two methods (Western blot and peptide enzyme immunoassay) for serologic distinction between HTLV-I and -II is described. These results were compared to those from polymerase chain reaction (PCR) analysis of HTLV proviral DNA obtained from donor peripheral blood mononuclear cells. The peptide enzyme immunoassay was found to be less sensitive than the Western blot, but completely concordant with PCR results when differential reactivity could be established. The Western blot pattern showed complete diagnostic concordance with the samples with confirmed-positive serologic tests, but was incorrect in two HTLV-II-infected donors with indeterminate serologic tests. Thirty-three (89%) of the 37 individuals from this predominantly Native American and Hispanic group of blood donors were found to have HTLV-II. These findings confirm and extend previous reports that HTLV-I infection may be less common, and HTLV-II infection more common, than previously believed. The peptide enzyme immunoassay can provide most individuals who have positive results with the HTLV-I/II screening test with serologic distinction between HTLV-I and HTLV-II.     

Simultaneous confirmation and differentiation of human T-lymphotropic virus types I and II infection by modified western blot containing recombinant envelope glycoproteins

A modified Western blot (WB) that includes both shared (r21e) and unique recombinant envelope proteins from human T-lymphotropic virus (HTLV) type I (rgp46I) and type II (rgp46II) was compared to conventional HTLV serologic tests in 379 United States blood donors and individuals residing in diverse geographic regions, and the specimens were categorized as positive (n = 158), indeterminate (n = 158), or negative (n = 63) for HTLV infection. Of the 158 HTLV-I/II-positive specimens (66 requiring radioimmunoprecipitation assay [RIPA] for confirmation), 156 reacted concordantly with r21e, gag, and either rgp46I or rgp46II, thus eliminating the need for RIPA in all but two specimens and yielding a test sensitivity of 98.7 percent. Of the 158 indeterminate and 63 negative specimens, none reacted with r21e and rgp46I or rgp46II, yielding a test specificity of 100 percent. Furthermore, analysis of an additional 184 consecutive specimens from a retrovirology reference laboratory demonstrated that the modified WB correctly identified 27 of 28 HTLV-I specimens and all 13 HTLV-II specimens, with a test sensitivity of 97.6 percent. None of specimens that were indeterminate or nonreactive in conventional WB and/or RIPA and none of the screening enzyme immunoassay-negative specimens reacted with r21e and either rgp46I or rgp46II, for a test specificity of 100 percent. Thus, the modified WB appears to be highly sensitive and specific for simultaneous detection and discrimination of HTLV-I from HTLV-II and has the advantage of being a one-step assay that is easily performed in all types of laboratory settings and allows rapid, reliable, and standardized testing for HTLV-I/II infection.     

Serologic and molecular typing of human T‐lymphotropic virus among blood donors in Maputo City,Mozambique

BACKGROUND: Screening for human T‐lymphotropic virus‐1/2 (HTLV‐1/2) infection is not performed in blood banks in Mozambique. The aim was to determine the prevalence of HTLV‐1/2 among blood donors of the Maputo Central Hospital Blood Bank and measure the coinfection rate of HTLV‐1/2 with human immunodeficiency virus (HIV), hepatitis B virus (HBV), and syphilis. STUDY DESIGN AND METHODS: A total of 2019 consecutive blood donors were screened for HTLV‐1/2 antibodies, HIV‐1/2 antibodies, hepatitis B surface antigen (HBsAg), and rapid plasma reagin (RPR) for syphilis. Specimens reactive on a first HTLV‐1/2 enzyme immunoassay (EIA) were retested using a second EIA. Specimens that were dually reactive on both EIAs were further tested using Western blot (WB) and real‐time polymerase chain reaction (PCR). RESULTS: All 18 dually reactive specimens (0.89%; 95% confidence interval, 0.48%‐1.30%) were positive for the presence of HTLV‐1 by WB and real‐time PCR. HTLV‐2 was not detected. The prevalences of anti‐HIV, HBsAg, and reactivity in the RPR test were 5.72, 6.01, and 0.98 percent, respectively. There was no significant association between HTLV‐1 infection and demographic variables (age and sex) or serologic markers (HIV, HBsAg, and RPR). For the 17 HTLV‐1–positive donors for whom serologic data for HIV, HBsAg, and syphilis RPR were available, 2 showed coinfection with HIV and 1 with HBV. CONCLUSION: Compared to other infectious agents, HTLV‐1 is present at relatively low levels among blood donors in Mozambique. Cost and logistics will present as major challenges for introducing HTLV‐1/2 screening in blood banks. In blood banks in Southern Africa where EIA testing is possible, a sequential algorithm of two EIAs may be a cost‐efficient option for HTLV‐1/2 screening.     

Contribution of polymerase chain reaction and radioimmunoprecipitation assay in the confirmation of human T-lymphotropic virus infection in French blood donors. Retrovirus Study Group of the French Society of Blood Transfusion

BACKGROUND: To verify the criteria for human T-lymphotropic virus (HTLV) seropositivity in Western blot (WB) proposed by the Retrovirus Study Group of the French Society of Blood Transfusion, 186 blood donations that were repeatedly reactive in HTLV enzyme-linked immunosorbent assay, selected according to their WB pattern, were tested by polymerase chain reaction (PCR) and radioimmunoprecipitation assay (RIPA). STUDY DESIGN AND METHODS: In two commercially available WBs, 12 samples were confirmed as positive (rgp21+p19+p24) and 174 were interpreted as indeterminate (one or two reactivities to these proteins). The primer pairs used for the PCR allowed the amplification of type I (HTLV-I) or type II (HTLV-II) (or both) sequences. The RIPA was performed with two 35S-labeled cell lines: HTLV-I infected HUT 102/B2 and HTLV-II-infected MoT. RESULTS: Of the 12 positive samples, 11 were classified as HTLV-I-positive and one as HTLV-II-positive. Among the 174 indeterminate samples, three (WB pattern: rgp21+, p19+, p24-) were HTLV-I positive in PCR (one of them was positive in RIPA also); the other 171 were HTLV negative. CONCLUSION: In the study of a population in which 97 percent of HTLV infections are due to HTLV-I, these data support the three-protein criteria (rgp21, p19, and p24) for a positive blot reading. No HTLV infection was observed when rgp21 did not react. Consequently, p19 and/or p24 band patterns represent false reactivity and do not require PCR or RIPA confirmation. To discriminate between false- and true-positive results in the absence of MTA-1 or K55 reactivity, PCR and/or RIPA is required only when rgp21 reactivity is associated with one gag band (p19 or p24).     

HTLV antibody screening using mini-pools

At the present time, the UK blood transfusion services do not screen blood donations for anti-HTLV. This presentation describes a pilot study to ascertain the feasibility of HTLV antibody screening using mini-pools and also provides an estimate of HTLV prevalence within our donor population in Scotland and Northern Ireland. The Abbott/Murex HTLV I/II GE80/81 ELISA was selected for the trial. Thirty confirmed HTLV positive library samples were tested at various dilutions and five were shown to be nonreactive at a dilution of 1:100. Residues of mini-pools (of up to 95 individual donations) prepared for HCV NAT testing were tested with the Abbott/Murex GE80/81 assay. Of 6666 mini-pools (equivalent to 570 609 donations) tested, six were repeatedly reactive. All six mini-pools were confirmed HTLV antibody positive by line immunoassay. Four were confirmed to be HTLV-I positive, one HTLV-II positive and one HTLV positive (unable to type). Dilutions (1:100) of the five HTLV "nonreactive" positive samples were included in each test plate and used to determine a grey-zone cut-off. Using this grey-zone system an additional six (0.09%) mini-pool samples gave repeatedly reactive grey-zone results, none of which were confirmed. The minimum Scottish/Irish HTLV donor prevalence was shown to be 1:95 000.     

丙型肝炎病毒抗体筛查阳性结果确证方案的探讨

目的明确抗-HCV酶免检测结果与确证阳性结果之间的相互关系,以期建立简便、经济的血液筛查实验室抗-HCV确证试验方案。方法使用重组免疫印迹试验结合核酸检测方法对134份酶免抗-HCV阳性样本确证,初步探讨2或3种抗-HCV酶免试剂(Ortho、Murex和科华联合复检的S/Co值与阳性预期值的关系及不同试剂组合检测的阳性预期值。结果134份样本中,92份真阳性,5份可疑,其余均为阴性。Ortho和Murex试剂的S/Co与阳性预期值呈正相关,当S/Co≥3.8时,阳性预期值分别可达98.33%和97.78%。Murex联合科华、Ortho联合科华以及3种试剂同时检测为阳性时的阳性预期值为100%;Ortho联合Murex的阳性预期值为98.48%,与上述其它2或3种试剂组合比较,差异无统计学意义(P>0.05)。结论2种或3种酶免试剂联合复检的确证方案优于美国CDC推荐的S/Co≥3.8方案。在常规血液筛查实验室,可以选择3种抗-HCV试剂中的任2种同时复检,先行对抗-HCV阳性标本确证,对无法确证的样本再作重组免疫印迹试验分析。     

Sensitivity and specificity of four assays to detect human T− lymphotropic virus type I or type I/II antibodies

BACKGROUND: Assays that detect human T-lymphotropic virus type I and type II antibody (HTLV-I/II) are widely used in the routine screening of blood donors. STUDY DESIGN AND METHODS: Four commercially available anti-HTLV-I (Fujirebio and Organon Teknika) or -HTLV-I/II assays (Murex and Ortho) were evaluated in various serum panels: A) HTLV-I-positive specimens (n = 41), confirmed by Western blot and polymerase chain reaction; B) a commercially available anti-HTLV-I/II panel; C) serial dilutions of sera from HTLV-I-positive individuals (n = 30), confirmed by immunofluorescence assay and Western blot: D) serial dilutions of HTLV-II-positive blood donors (n = 20), confirmed by Western blot and polymerase chain reaction, and E) sera from first-time blood donors (n = 1055). RESULTS: All four assays elicited reactions in all 82 HTLV-I- positive samples in Panels A, B, and C. Of 32 HTLV-II-positive specimens in Panels B and D, 31 (96.9%) reacted in the Organon Teknika assay and all 32 reacted in the remaining tests. Probit analysis of test results in Panels C and D indicated that the Fujirebio test was the most sensitive assay, followed by Organon Teknika, Ortho, and Murex. The specificities of Fujirebio, Murex, Organon Teknika, and Ortho tests in 1055 first-time blood donors were 99.9, 100, 99.6, and 99.9 percent, respectively. CONCLUSION: All four studied assays for detecting HTLV-I or HTLV-I/II antibodies are appropriate as screening tests.     

Transfusion-associated transmission of human T-lymphotropic virus types I and II: experience of a regional blood center

During a 22-month period, 78,000 blood donors were screened for human T- lymphotropic virus types I and II (HTLV-I/II) at Belle Bonfils Memorial Blood Center (Denver, Colorado). Positive donors and the living recipients of their previously donated blood components were evaluated for risk factors and symptoms related to HTLV-I infection, were screened by enzyme immunoassay, confirmed by Western blot for HTLV- I/II, and subsequently tested by polymerase chain reaction and peptide enzyme immunoassay to distinguish between HTLV-I and -II infection. Six seropositive blood donors (0.008%) were identified; four were typed as having HTLV-I infection and two as having HTLV-II. Of 18 living recipients of components from seropositive donors, none had risk factors for HTLV-I infection prior to transfusion and none had signs or symptoms of HTLV-I infection at follow-up. The mean time from transfusion to testing was 6.4 years. Seven recipients of HTLV-I- infected components were HTLV seropositive; all were typed as having HTLV-I. A possible case of posttransfusion HTLV-I-associated myelopathy was identified in one patient who died before complete evaluation. One possible case of transfusion-associated HTLV-II was identified. These data further support the continued screening of blood donors for HTLV- I/II.     

Absence of human T-lymphotropic virus types I and II infection in an Ontario hemophilia population

Two hundred ninety-three serum samples from Ontario hemophiliacs and 200 samples from human immunodeficiency virus-positive blood donors were screened for the presence of antibodies to human T-lymphotropic virus type I (HTLV-I) by enzyme-linked immunosorbent assay, radioimmunoassay, and Western blot techniques. None of the serum samples provided unequivocal positive results, but several samples gave inconclusive results. Of the hemophiliacs with inconclusive serologic results from whom peripheral blood lymphocyte DNA could be obtained, all were negative for HTLV-I and HTLV type II (HTLV-II) sequences as determined by polymerase chain reaction (PCR). PCR was also performed on a lymph node biopsy sample taken from a hemophiliac who developed a rare T-cell lymphoma; the sample was negative for HTLV-I and -II sequences. These results indicate that Ontario hemophiliacs have not been exposed to HTLV-I or HTLV-II.     

Transfusion transmission of human T-lymphotropic virus types I and II: serologic and polymerase chain reaction results in recipients identified through look-back investigations

To determine the transmissibility of human T-lymphotropic virus types I and II (HTLV-I and HTLV-II) via transfusion, persons who, from 1983 to 1989, received blood components donated by persons who subsequently tested anti-HTLV-I-positive were evaluated. It was found that 16 (30%) of 54 evaluable recipients of transfused cellular components became infected with one of the HTLVs: 8 had HTLV-I and 8 had HTLV-II. Forty percent of platelet recipients and 28 percent of red cell recipients acquired infection. The rate of transmission of HTLV-I and HTLV-II was significantly correlated with storage age of red cell units prior to transfusion: 47 percent for red cells stored < or = 14 days and 0 for red cells stored > 14 days (p < 0.01). Multiple confirmatory serologic tests performed in 46 anti-HTLV-I enzyme immunoassay-negative recipients revealed that HTLV infection could not be excluded in 3 recipients of blood components from HTLV-II-infected donors. Polymerase chain reaction established HTLV-II infection in one recipient, and the other two recipients could not be classified with respect to HTLV infection status. It appears that some HTLV-II-infected transfusion recipients will not be detected by existing HTLV-I antigen-based reagents. If it is deemed necessary to initiate or continue look-back programs to detect transfusion transmission of HTLV-II infection, it is suggested that the current testing algorithm be modified in selected cases.     

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

BACKGROUND: A new generation of assays for the detection of human T-lymphotropic virus types I and II (HTLV-I/II) antibodies has been released. These assays incorporate HTLV-I- and HTLV-II-specific antigens, and some are based on new assay principles. Comparative evaluation data that include these new as well as previous assays are limited. STUDY DESIGN AND METHODS: Fourteen HTLV antibody assays were evaluated by using well-characterized panels of sera from Guinea-Bissau, West Africa, and Sweden. The sera included 127 HTLV-I-positive and 62 HTLV-II-positive specimens, as well as 919 consecutive negative samples. RESULTS: The sensitivity for HTLV-I was 100 percent for all assays, except one, which repeatedly missed one sample. The sensitivity for HTLV-II varied between 86 percent and 100 percent. In general, new-generation assays incorporating HTLV-II-specific antigens, and some of which are based on new assay principles, had a higher sensitivity for HTLV-II than previous assays, which mainly are based on HTLV-I antigens. The specificity was generally higher for new assays than for the previous versions. Testing of Swedish blood donor sera gave higher specificities (94-100%) than did that of African specimens (90-99.7%). Most assays had low delta values (DVs), although there was a tendency toward increased DVs for the new generation of assays. Only two of the new generation of assays came close to a combination of high sensitivity for both HTLV-I and HTLV-II, high specificity, positive and negative predictive values, and high DVs. CONCLUSION: The sensitivity for HTLV-I was generally high and appears to have improved for HTLV-II with the introduction of a new generation of assays incorporating HTLV-II-specific antigens. However, some assays still give false-negative results on HTLV-II-positive specimens. The specificities and the DVs were generally higher for the new assays than for the previous versions.     

Low incidence of HTLV infections in random blood donors with indeterminate western blot patterns

Peripheral blood mononuclear cells (PBMCs) were recovered from platelet units of 61 blood donors who were HTLV-I positive and 3 blood donors who were HTLV-I negative on enzyme-linked immunosorbent assay (ELISA). Western blot analyses were performed on the sera and DNA was prepared from the PBMCs and analyzed by the polymerase chain reaction (PCR). Of the 61 repeatably reactive samples, 2 were positive, 26 were negative, and 33 were interpreted as indeterminate on Western blot. HTLV-II sequences were detected by PCR in one of the Western blot-positive samples, as well as in one Western blot-indeterminate sample that showed reactivity to p24 only. HTLV-I sequences were detected in the second Western blot-positive sample. HTLV sequences were not detected in the remaining samples, which suggested that the majority of individuals with indeterminate results on Western blots that used one set of commercially available reagents are not infected with HTLV. It is demonstrated in this study that PCR can be used not only to resolve the infection status of individuals with indeterminate Western blots but also to distinguish between HTLV-I and HTLV-II.     

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

SUMMARY. The Wellcozyme HTLV-I/II ELISA (Murex Diagnostics) was evaluated in 7800 samples of various serum panels. Repeat reactivity 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% in 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.     

HTLV-I/II prevalence in different geographic locations

Human T-cell lymphotropic virus (HTLV) type I (HTLV-I) is the etiological agent of adult T-cell leukemia and HTLV-I-associated myelopathy/tropical spastic paraparesis (HAM/TSP). HTLV-II is a closely related virus, and this infection is not clearly associated with clinical disease, although neurologic disorders are observed resembling HAM/TSP. Prevalence rates for HTLV-I infection in the general population are greater than 1% in the Caribbean Basin, Central Africa, and South Japan. In most other areas in the world, as far as we know, HTLV-I/II infections are mainly found in high-risk groups (ie, immigrants from endemic areas, their offspring, their sexual contacts and in patients and intravenous injection users attending sexually transmitted disease clinics). Also, a high rate of infection for both HTLV-I and HTLV-II infection was observed in the native Amerindian population in North America as well as South America. Blood donors are routinely screened for HTLV-I/II in North America, several countries in Europe, Japan, and Taiwan.     

广东籍献血人群HTLV感染状况调查

目的了解东南沿海省份的元症状献血人群人类嗜T淋巴细胞病毒（human T cell lymphotvopic virus,HTLV）的血清学流行状况。方法从符合卫生部健康标准并经血液常规检测合格的标本中,依据籍贯选择性收集2500份血样,采用双抗原夹心的酶免吸附（EIA）方法进行HTLV-Ⅰ／Ⅱ抗体筛查。EIA初筛阳性结果经复检后,由蛋白印迹法（Western Blot,WB）进行确认试验。结果初筛获得EIA反应性样本5例,HTLV抗体阳性率为0．20％（5／2500）,均为广东籍。经蛋白印迹试验,仅1例OD值为3．00的EIA强反应者获确认为HTLV—Ⅰ型病毒感染,2例未获确认,2例为确认阴性。经追溯,确认HTLV—Ⅰ阳性者为无症状定期献血者,已有6次合格献血经历。结论尽管深圳献血人群HTLV流行率的总体水平较低,但多次献血的经历使经血传播HTLV的风险增大数倍。