Performance evaluation of newly developed surrogate virus neutralization tests for detecting neutralizing antibodies against SARS-CoV-2.

We evaluated newly developed surrogate virus neutralization tests (sVNT) for detecting neutralizing antibodies (NAbs) against the receptor binding domain of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). VERI-Q SARS-CoV-2 Neutralizing Antibody Detection ELISA Kit (MiCo BioMed, Gyeonggi-do, Republic of Korea, hereafter, "eCoV-CN") is an enzyme-linked immunosorbent assay-based sVNT, and VERI-Q SARS-CoV-2 Neutralizing Antibody Rapid Test Kit (MiCo BioMed, hereafter, "rCoV-RN") is a point-of-care lateral-flow immunochromatography test with auto-scanner. A total of 411 serum samples were evaluated. Both evaluations used a 50% plaque reduction neutralization test (PRNT50) as the gold standard. Compared with PRNT50, the eCoV-CN showed 98.7% positive percent agreement (PPA), 96.8% negative percent agreement (NPA), 97.4% total percent agreement (TPA), with kappa values of 0.942. The rCoV-RN showed 98.7% PPA, 97.4% NPA, 97.8% TPA, and kappa values of 0.951, comparing to PRNT50. Neither assay indicated cross-reactivity for other pathogens, and the signal indexes were statistically significantly correlated to the PRNT50 titer. The two evaluated sVNTs show comparable performances to the PRNT50 with the advantages of technical simplicity, speed, and do not require cell culture facilities.

Evaluation of R-FIND SARS-CoV-2 Neutralizing Antibody ELISA and FREND COVID-19 SP Rapid Fluorescence Immunoassay.

BACKGROUND: Serology testing is useful to determine the past infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). METHODS: We evaluated the comparative performance of a newly developed neutralizing antibody test (R-FIND SARS-CoV-2 Neutralizing Antibody ELISA, SG Medical, Seoul, Korea) and a rapid fluorescence immunoassay (FREND™ COVID-19 SP, NanoEntek, Hwaseong, Korea) for the detection of SARS-CoV-2 spike protein antibody. They were compared with cPass™ SARS-CoV-2 Neutralization Antibody Detection Kit (Genscript Biotech, Piscataway, NJ, USA) and ADVIA Centaur SARS-CoV-2 Total (COV2T) (Siemens Healthineers, Erlangen, Germany). Forty COVID-19 samples and 80 negative samples were collected after nucleic acid tests. RESULTS: The positive percent agreement (%) of the kit in samples from 6 - 7 days, 8 - 14 days, and 15 - 45 days after symptom onset were as follows: R-FIND (83.3, 76.9, 95.2), cPass (83.3, 69.2, 90.5), FREND (66.6, 84.6, 100), and COV2T (66.6, 69.2, 76.2). The negative percent agreement (%) was 100, 97.5, 92.5, and 100 for R-FIND, cPass, FREND, and COV2T. The total agreement rate between the neutralizing antibody kits (R-FIND and cPass) was 96.7%. FREND showed high agreement with two neutralizing antibody kits (96.7% for R-FIND and 93.3% for cPass). CONCLUSIONS: R-FIND Neutralizing Antibody and FREND COVID-19 SP showed comparable detecting ability to commercial tests.

Development and Evaluation of AccuPower COVID-19 Multiplex Real-Time RT-PCR Kit and AccuPower SARS-CoV-2 Multiplex Real-Time RT-PCR Kit for SARS-CoV-2 Detection in Sputum, NPS/OPS, Saliva and Pooled Samples.

Rapid and accurate detection of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is essential for the successful control of the current global COVID-19 pandemic. The real-time reverse transcription polymerase chain reaction (Real-time RT-PCR) is the most widely used detection technique. This research describes the development of two novel multiplex real-time RT-PCR kits, AccuPower® COVID-19 Multiplex Real-Time RT-PCR Kit (NCVM) specifically designed for use with the ExiStation™48 system (comprised of ExiPrep™48 Dx and Exicycler™96 by BIONEER, Korea) for sample RNA extraction and PCR detection, and AccuPower® SARS-CoV-2 Multiplex Real-Time RT-PCR Kit (SCVM) designed to be compatible with manufacturers' on-market PCR instruments. The limit of detection (LoD) of NCVM was 120 copies/mL and the LoD of the SCVM was 2 copies/µL for both the Pan-sarbecovirus gene and the SARS-CoV-2 gene. The AccuPower® kits demonstrated high precision with no cross reactivity to other respiratory-related microorganisms. The clinical performance of AccuPower® kits was evaluated using the following clinical samples: sputum and nasopharyngeal/oropharyngeal swab (NPS/OPS) samples. Overall agreement of the AccuPower® kits with a Food and Drug Administration (FDA) approved emergency use authorized commercial kit (STANDARD™ M nCoV Real-Time Detection kit, SD BIOSENSOR, Korea) was above 95% (Cohen's kappa coefficient ≥ 0.95), with a sensitivity of over 95%. The NPS/OPS specimen pooling experiment was conducted to verify the usability of AccuPower® kits on pooled samples and the results showed greater than 90% agreement with individual NPS/OPS samples. The clinical performance of AccuPower® kits with saliva samples was also compared with NPS/OPS samples and demonstrated over 95% agreement (Cohen's kappa coefficient > 0.95). This study shows the BIONEER NCVM and SCVM assays are comparable with the current standard confirmation assay and are suitable for effective clinical management and control of SARS-CoV-2.