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

Prevalence of transfusion-transmitted infections in hospitalized patients before transfusion and volunteer blood donors in Zhejiang Province, China

OBJECTIVES

To assess the need for screening of transfusion-transmitted infections (TTIs) in blood products, we assessed TTI seroprevalence in blood donors and hospitalized patients.

METHODS

We collected 2760 serum samples from three regions of Hangzhou, Ningbo and Huzhou from April 2021 to March 2022, and they tested by enzyme-linked immunosorbent assay (ELISA) for Hepatitis B surface antigen (HBsAg), Hepatitis C (HCV), Treponema pallidum (TP), Cytomegalovirus (CMV), Epstein-Barr virus (EBV), Hepatitis E virus (HEV) and Human T-cell lymphotropic virus type 1/2 (HTLV-1/2) antibody levels.

RESULTS

Screening test results showed that the positive rates for HBsAg, anti-HCV and anti-TP were 3.01 %, 0.39 % and 0.18 %, respectively. The positive rates for CMV IgM and CMV IgG were 0.76 % and 96.96 %, while the positive rates for EB VCA-IgM and EB EA-IgG were 1.88 % and 10.47 %; those for HEV IgM and HEV IgG were 1.16 % and 26.05 %, while the HTLV-1/2 antibody positive rate was 0.04 %. The positive rates for CMV IgG, EB EA-IgG and HEV IgG in hospitalized patients before transfusion were higher than in volunteer blood donors, and the difference was statistically significant (P < 0.05). The overall co-infection rate was 0.29 %. The positive rates for EB VCA-IgM in the males were significantly higher than in females, and EB VCA-IgM and HEV IgG prevalence varied significantly by age.

CONCLUSION

Our data demonstrate the risk of TTI exposure and TTI transmission in the Zhejiang population, which poses a threat to blood safety. It is hoped that expansion of pathogen categories (CMV, EBV, HEV and HTLV-1/2) and blood screening programs will contribute to the future adoption of scientific blood transfusion methods.

Evaluation of human T-cell leukemia virus in vitro diagnostics using plasma specimens collected in Japan

BACKGROUND

In vitro diagnostics (IVDs) for primary detection test/screening of human T-cell leukemia virus (HTLV) have recently been updated to new-generation products in Japan. In this study, the performance of these products was evaluated and discussed in terms of the usability of HTLV diagnosis in Japan.

METHODS

The performance of 10 HTLV IVDs for primary detection test and confirmatory/discriminatory test was evaluated. Plasma specimens that had been declared ineligible for transfusion were provided by the Japanese Red Cross Blood Center.

RESULTS

The diagnostic specificity of the IVDs was 100% (160/160). Six sandwich assays resulted in all HTLV-1/HTLV-positive specimens being positive (46/46). On the other hand, one sandwich assay, IVD under development 2 (UD2), resulted in one HTLV-1-positive and one HTLV-positive specimen being negative (44/46, 95.7%). One indirect assay, HISCL HTLV-1, could not detect one HTLV-positive specimen (45/46, 97.8%), but the updated product, UD1, correctly detected it (46/46, 100%). Serodia HTLV-I, based on a particle agglutination assay, resulted in 44 of the 46 positive specimens, but could not detect two specimens (44/46, 95.7%). ESPLINE HTLV-I/II, based on an immunochromatography assay (ICA), was able to diagnose all specimens as positive (46/46, 100%).

CONCLUSIONS

Six sandwich assays and an ICA demonstrated high diagnostic sensitivity and specificity and are recommended for use in HTLV diagnosis in conjunction with confirmatory/discriminatory test using the INNO-LIA HTLV-I/II Score.

Novel Genetic Constructs for Production of Recombinant HTLV-1/2 Antigens and Evaluation of Their Reactivity to Plasma Samples from HTLV-1-Infected Patients

Human T-cell leukemia virus type 1 (HTLV-1) can cause life-threatening diseases for which there are no effective treatments. Prevention of HTLV-1 infection requires massive testing of pregnant women, blood for transfusion, and organs for transplantation, as well as safe sex. In this context, serological assays are widely used for monitoring HTLV-1 infections. Despite the necessity for recombinant antigens to compose serological tests, there is little information available on procedures to produce recombinant HTLV-1/2 antigens for serological diagnostic purposes. In this work, we tested a series of genetic constructions to select those more amenable for production in bacterial systems. To overcome the constraints in expressing sections of viral envelope proteins in bacteria, we have used the p24 segment of the gag protein as a scaffold to display the immunogenic regions of gp46 and gp21. Nine recombinant antigenic proteins derived from HTLV-1 and five derived from HTLV-2 were successfully purified. The HTLV-1 antigens showed high efficiency in discriminating HTLV-positive samples from HTLV-negative samples using enzyme-linked immunosorbent assays. Interestingly, HTLV-1-positive samples showed a high level of cross-reaction with HTLV-2 antigens. This finding is explained by the high sequence conservation between the structural proteins of these two highly related viruses. In summary, the results presented in this work provide a detailed description of the methods used to produce recombinant HTLV-1 and HTLV-2 antigens, and they demonstrate that the HTLV-1 antigens show strong potential for serological diagnosis of HTLV-1 infections.

Establishment of a novel diagnostic test algorithm for human T-cell leukemia virus type 1 infection with line immunoassay replacement of western blotting: a collaborative study for performance evaluation of diagnostic assays in Japan

BACKGROUND

The reliable diagnosis of human T-cell leukemia virus type 1 (HTLV-1) infection is important, particularly as it can be vertically transmitted by breast feeding mothers to their infants. However, current diagnosis in Japan requires a confirmatory western blot (WB) test after screening/primary testing for HTLV-1 antibodies, but this test often gives indeterminate results. Thus, this collaborative study evaluated the reliability of diagnostic assays for HTLV-1 infection, including a WB-based one, along with line immunoassay (LIA) as an alternative to WB for confirmatory testing.

RESULTS

Using peripheral blood samples from blood donors and pregnant women previously serologically screened and subjected to WB analysis, we analyzed the performances of 10 HTLV-1 antibody assay kits commercially available in Japan. No marked differences in the performances of eight of the screening kits were apparent. However, LIA determined most of the WB-indeterminate samples to be conclusively positive or negative (an 88.0% detection rate). When we also compared the sensitivity to HTLV-1 envelope gp21 with that of other antigens by LIA, the sensitivity to gp21 was the strongest. When we also compared the sensitivity to envelope gp46 by LIA with that of WB, LIA showed stronger sensitivity to gp46 than WB did. These findings indicate that LIA is an alternative confirmatory test to WB analysis without gp21. Therefore, we established a novel diagnostic test algorithm for HTLV-1 infection in Japan, including both the performance of a confirmatory test where LIA replaced WB on primary test-reactive samples and an additional decision based on a standardized nucleic acid detection step (polymerase chain reaction, PCR) on the confirmatory test-indeterminate samples. The final assessment of the clinical usefulness of this algorithm involved performing WB analysis, LIA, and/or PCR in parallel for confirmatory testing of known reactive samples serologically screened at clinical laboratories. Consequently, LIA followed by PCR (LIA/PCR), but neither WB/PCR nor PCR/LIA, was found to be the most reliable diagnostic algorithm.

CONCLUSIONS

Because the above results show that our novel algorithm is clinically useful, we propose that it is recommended for solving the aforementioned WB-associated reliability issues and for providing a more rapid and precise diagnosis of HTLV-1 infection.

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.