The sensitivity of the LFIAs characterized herein suggests that such an approach would have only a minor impact on clinical sensitivity overall by using 2 assays. suggest that LFIAs may provide adequate results for rapid detection of SARS-CoV-2. strong class=”kwd-title” Keywords: SARS-CoV-2, COVID-19, Lateral flow, Immunoassay, Serology, IgG 1.?Introduction Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) emerged in 2019 as the causative agent of coronavirus disease 2019 (COVID-19), a pandemic respiratory infection resulting in over 14 million cases and 600,000 deaths between November 2019 and July 2020 (WHO, 2020). Antibody detection is currently being implemented in many clinical centers to aid in identification of recent disease and to investigate population seroprevalence. Accurate laboratory tests impact clinical decision making, and understanding performance of a test is essential to determination of when to use the test and what the results might mean. For example, specificity is of particular importance in a low-prevalence setting (Farnsworth and Anderson, 2020). Lateral flow immunoassays (LFIAs) are an attractive alternative or supplement to automated enzyme-linked immunosorbent assay and chemiluminescence assays as they require less operator skill and for their potential utility in a point-of-care setting. Here we evaluated 4 LFIAs for the detection of antiCSARS-CoV-2 IgG in clinical samples. 2.?Materials and methods 2.1. Patient population and clinical specimens Deidentified, presumptive positive specimens ( em n /em ?=?352) from 62 individuals with reverse-transcription polymerase chain reaction (RT-PCR)Cconfirmed COVID-19 were kindly shared by the Department of Laboratory Medicine at the University of Washington School of Medicine (Seattle, WA) with limited metadata, such as Abbott SARS-CoV-2 IgG immunoassay results and the number of days since symptom onset. These consisted of 250 plasma, 77 serum, and 21 whole blood specimens (a further 4 unknown specimens were assumed to be either serum or plasma); were received frozen; and underwent either 1 or 2 2 freezeCthaw cycles prior to testing. Specificity specimens were obtained from 2 sources: 74 excess clinical serum specimens collected and stored in 2018, and 31 cross-reactivity challenge specimens collected between March and April 2020. Among these 105 specimens, there were 27 from individuals with a history of seasonal coronavirus infection (as determined by a syndromic respiratory PCR test) within 3?years prior to collection (HKU1, em n /em ?=?13; NL63, em n /em ?=?6; OC43, em n /em ?=?6; 229E, em n /em ?=?2); 2 specimens reactive for rheumatoid factor; 1 reactive for HIV-1 antibody, HAV total antibody, HBV core total antibody and surface antibody, and RPR; and 1 reactive for HCV antibody and HSV2 antibody (Table 1 ). These specimens were tested after 0, 1, or 2 freezeCthaw cycles. Table 1 Specimens selected in this study for their potential to contain cross-reactive antibodies, where time elapsed refers to the time between PCR detection of the virus (CR1C27) or other potentially interfering substance (CR28C31) and collection of the blood specimen used in this study. thead th rowspan=”1″ colspan=”1″ Sample ID /th th rowspan=”1″ colspan=”1″ Interfering substance /th th rowspan=”1″ colspan=”1″ Time CZ415 elapsed (d) /th /thead CR01History of coronavirus HKU1 infection28CR02History of coronavirus HKU1 infection46CR03History of coronavirus HKU1 infection74CR04History of coronavirus HKU1 infection82CR05History of coronavirus HKU1 infection84CR06History of coronavirus HKU1 infection85CR07History of coronavirus HKU1 infection96CR08History of coronavirus HKU1 infection108CR09History of coronavirus HKU1 infection108CR10History of coronavirus HKU1 infection116CR11History of coronavirus HKU1 infection120CR12History of coronavirus HKU1 infection127CR13History of coronavirus HKU1 infection146CR14History of coronavirus NL63 infection1CR15History of coronavirus NL63 infection19CR16History of coronavirus NL63 infection53CR17History of coronavirus NL63 infection411CR18History of coronavirus NL63 infection452CR19History of coronavirus NL63 infection530CR20History of coronavirus OC43 infection103CR21History of coronavirus OC43 infection241CR22History of coronavirus OC43 infection370CR23History of coronavirus OC43 infection440CR24History of coronavirus OC43 infection863CR25History of coronavirus OC43 infection1159CR26History of coronavirus 229E infection118CR27History of coronavirus 229E infection448CR28Rheumatoid result of 630CR29Rheumatoid result of 270CR30HSV2 Ab, HCV Ab0CR31HIV-1 Ab, HAV total, HBc total, HBsAb, RPR(1:4)0 Open in a separate window 2.2. LFIAs Rapid Response? COVID-19 Test Cassette (BTNX Inc.): We CZ415 tested 2 different iterations of this kit, hereafter referred to as BTNX kit 1 and BTNX kit 2. LFIAs were performed DFNB53 according to the manufacturer’s instructions. Briefly, for BTNX kit 1, 10?L serum, plasma, or whole blood was transferred to the sample well, followed by 1 drop of assay buffer; results were read and interpreted after 10C15?min. For BTNX kit 2, 5?L serum, plasma, or whole blood was transferred to the sample well, followed by 2 drops of assay buffer; results were read after 15?min. SARS-COV-2 IgG/IgM Rapid Test CZ415 (ACON Laboratories): For this assay, hereafter referred to as ACON, 10?L serum or plasma, or 15?L whole blood was transferred to the specimen well, and then 2 drops of buffer were added to the buffer well; results were read after 10C15?min. Standard Q COVID-19 IgM/IgG Duo (SD BIOSENSOR): This kit is.
The sensitivity of the LFIAs characterized herein suggests that such an approach would have only a minor impact on clinical sensitivity overall by using 2 assays