tetano
Editor, Senior Moderator
PLoS One
. 2021 Mar 4;16(3):e0247711.
doi: 10.1371/journal.pone.0247711. eCollection 2021.
Validation of a new automated chemiluminescent anti-SARS-CoV-2 IgM and IgG antibody assay system detecting both N and S proteins in Japan
Rin Yokoyama[SUP] 1 [/SUP], Makoto Kurano[SUP] 1 2 [/SUP], Yoshifumi Morita[SUP] 1 [/SUP], Takuya Shimura[SUP] 1 [/SUP], Yuki Nakano[SUP] 1 [/SUP], Chungen Qian[SUP] 3 [/SUP], Fuzhen Xia[SUP] 4 [/SUP], Fan He[SUP] 4 [/SUP], Yoshiro Kishi[SUP] 5 [/SUP], Jun Okada[SUP] 5 [/SUP], Naoyuki Yoshikawa[SUP] 1 [/SUP], Yutaka Nagura[SUP] 6 [/SUP], Hitoshi Okazaki[SUP] 6 [/SUP], Kyoji Moriya[SUP] 7 [/SUP], Yasuyuki Seto[SUP] 8 [/SUP], Tatsuhiko Kodama[SUP] 9 [/SUP], Yutaka Yatomi[SUP] 1 2 [/SUP]
Affiliations
Abstract
PCR methods are presently the standard for the diagnosis of Coronavirus disease 2019 (COVID-19), but additional methodologies are needed to complement PCR methods, which have some limitations. Here, we validated and investigated the usefulness of measuring serum antibodies against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) using the iFlash3000 CLIA analyzer. We measured IgM and IgG titers against SARS-CoV-2 in sera collected from 26 PCR-positive COVID-19 patients, 53 COVID-19-suspected but PCR-negative patients, and 20 and 100 randomly selected non-COVID-19 patients who visited our hospital in 2020 and 2017, respectively. The repeatability and within-laboratory precision were obviously good in validations, following to the CLSI document EP15-A3. Linearity was also considered good between 0.6 AU/mL and 112.7 AU/mL for SARS-CoV-2 IgM and between 3.2 AU/mL and 55.3 AU/mL for SARS-CoV-2 IgG, while the linearity curves plateaued above the upper measurement range. We also confirmed that the seroconversion and no-antibody titers were over the cutoff values in all 100 serum samples collected in 2017. These results indicate that this measurement system successfully detects SARS-CoV-2 IgM/IgG. We observed four false-positive cases in the IgM assay and no false-positive cases in the IgG assay when 111 serum samples known to contain autoantibodies were evaluated. The concordance rates of the antibody test with the PCR test were 98.1% for SARS-CoV-2 IgM and 100% for IgG among PCR-negative cases and 30.8% for SARS-CoV-2 IgM and 73.1% for SARS-CoV-2 IgG among PCR-positive cases. In conclusion, the performance of this new automated method for detecting antibody against both N and S proteins of SARS-CoV-2 is sufficient for use in laboratory testing.
. 2021 Mar 4;16(3):e0247711.
doi: 10.1371/journal.pone.0247711. eCollection 2021.
Validation of a new automated chemiluminescent anti-SARS-CoV-2 IgM and IgG antibody assay system detecting both N and S proteins in Japan
Rin Yokoyama[SUP] 1 [/SUP], Makoto Kurano[SUP] 1 2 [/SUP], Yoshifumi Morita[SUP] 1 [/SUP], Takuya Shimura[SUP] 1 [/SUP], Yuki Nakano[SUP] 1 [/SUP], Chungen Qian[SUP] 3 [/SUP], Fuzhen Xia[SUP] 4 [/SUP], Fan He[SUP] 4 [/SUP], Yoshiro Kishi[SUP] 5 [/SUP], Jun Okada[SUP] 5 [/SUP], Naoyuki Yoshikawa[SUP] 1 [/SUP], Yutaka Nagura[SUP] 6 [/SUP], Hitoshi Okazaki[SUP] 6 [/SUP], Kyoji Moriya[SUP] 7 [/SUP], Yasuyuki Seto[SUP] 8 [/SUP], Tatsuhiko Kodama[SUP] 9 [/SUP], Yutaka Yatomi[SUP] 1 2 [/SUP]
Affiliations
- PMID: 33661990
- DOI: 10.1371/journal.pone.0247711
Abstract
PCR methods are presently the standard for the diagnosis of Coronavirus disease 2019 (COVID-19), but additional methodologies are needed to complement PCR methods, which have some limitations. Here, we validated and investigated the usefulness of measuring serum antibodies against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) using the iFlash3000 CLIA analyzer. We measured IgM and IgG titers against SARS-CoV-2 in sera collected from 26 PCR-positive COVID-19 patients, 53 COVID-19-suspected but PCR-negative patients, and 20 and 100 randomly selected non-COVID-19 patients who visited our hospital in 2020 and 2017, respectively. The repeatability and within-laboratory precision were obviously good in validations, following to the CLSI document EP15-A3. Linearity was also considered good between 0.6 AU/mL and 112.7 AU/mL for SARS-CoV-2 IgM and between 3.2 AU/mL and 55.3 AU/mL for SARS-CoV-2 IgG, while the linearity curves plateaued above the upper measurement range. We also confirmed that the seroconversion and no-antibody titers were over the cutoff values in all 100 serum samples collected in 2017. These results indicate that this measurement system successfully detects SARS-CoV-2 IgM/IgG. We observed four false-positive cases in the IgM assay and no false-positive cases in the IgG assay when 111 serum samples known to contain autoantibodies were evaluated. The concordance rates of the antibody test with the PCR test were 98.1% for SARS-CoV-2 IgM and 100% for IgG among PCR-negative cases and 30.8% for SARS-CoV-2 IgM and 73.1% for SARS-CoV-2 IgG among PCR-positive cases. In conclusion, the performance of this new automated method for detecting antibody against both N and S proteins of SARS-CoV-2 is sufficient for use in laboratory testing.