Evaluation for IgG stability of the Abbott and Diasorin assays for specimen type (lithium heparin, plasma, serum) was compared using a one-way ANOVA while comparison of the three different temperatures evaluated were compared using a multivariate ANOVA. All three specimen types were collected from 34 COVID-19 recovered seropositive individuals (21 days post-symptoms). Using the Architect and Liaison assays, a positive qualitative SARS-CoV-2 IgG result was detected daily up to 12 FTCs and up to 10 days of storage at different temperatures. An additional 25 plasma samples consistently demonstrated detection of SARS-CoV-2 antibodies daily after 12 FTCs and storage Rabbit polyclonal to NF-kappaB p65.NFKB1 (MIM 164011) or NFKB2 (MIM 164012) is bound to REL (MIM 164910), RELA, or RELB (MIM 604758) to form the NFKB complex. at -20C using two rapid test cassette assays (SD Biosensor and Hangzhou All Test), manual (Beijing Wantai) and surrogate neutralization (GenScript) ELISAs, and two high-throughput assays (Roche Elecsys nucleocapsid and spike). IgM antibodies were less Icotinib Icotinib frequently detected by one of the rapid test cassette assays. Conclusions : Serum, plasma, and heparinized-plasma constitute reliable samples for SARS-CoV-2 antibody detection. In particular, the IgG response was stable and reliably detected after multiple FTCs and storage at common laboratory conditions. IgM detection was variable due to the labile nature of this antibody class. Keywords: SARS-CoV-2 IgG, Stability, Lithium heparin, Plasma, Serum, Freeze-thaw cycle Abbreviations: FTC, freeze-thaw cycle; Icotinib DSO, date of symptom-onset; CBS, Canadian Blood Services; PRNT, plaque reduction neutralization test; NML, National Microbiology Laboratory; SVNT, surrogate virus neutralization test Introduction The principal utility of SARS-CoV-2 IgG high throughput assays is conducting seroprevalence studies of different populations. Most surveys use serum, plasma, or heparinized-plasma [1]. While it is presumed these three specimen types are Icotinib likely equivalent, some studies have demonstrated that the yield of SARS-CoV-2 IgG results from these specimen types can differ based on the assay [2]. A number of studies have documented the stability of IgG antibodies produced to other viruses (eg. herpes simplex, varicella zoster, measles, mumps, rubella) when blood samples are stored or exposed to a variety of laboratory conditions [3], [4], [5]. Such conditions include multiple FTCs, varying storage temperatures, and prolonged storage over time. Variables in these studies that limit comparison include use or non-use of storage matrix (such as bovine-serum albumin or phosphate-buffered saline), and type of assay being used to measure antibody level (such as immunofluorescence assays versus ELISA versus large automated high-throughput systems). To-date however, there are a paucity of studies evaluating the stability of SARS-CoV-2 antibodies, including IgG, in different laboratory conditions and its overall effect on the quality of the result generated. In addition to serum, we aimed to evaluate the utility of plasma and heparinized-plasma samples as alternate sample types for SARS-CoV-2 antibody detection and assess the stability of these types across different temperatures and FTCs. Materials and methods Participant sample collection Serum and plasma blood samples were collected simultaneously from a group of 37 COVID-19 recovered individuals with laboratory-confirmed SARS-CoV-2 infection, diagnosed using molecular assays [6, 7]. Samples were collected 21 days post date of symptom onset (DSO). A subset (34 of 37) additionally submitted heparinized-plasma blood samples. A parallel study was conducted on plasma samples collected by Canadian Blood Services (CBS) from donors who self-identified as having recovered from COVID-19. Samples were previously tested by a SARS-CoV-2 plaque reduction neutralization test (PRNT). In total, 25 samples with PRNT titers ranging from 1:40C1:640 were selected for this study. Clinical information and demographics were not available for this cohort of patients. SARS-CoV-2 antibody stability Samples were initially stored at ?20C and underwent one FTC prior to aliquoting. SARS-CoV-2 IgG detection was performed using the Architect SARS-CoV-2 IgG and Liaison SARS-CoV-2 S1/S2 IgG qualitative assays (Table?1 ) [1]. One 600 L sample of each Icotinib specimen type (serum, plasma, or heparinized-plasma) was stored at ?70C and underwent repeated FTCs over 10 consecutive days, while single-use 200 L aliquots from the same affected individual were stored at 3 different temperatures (?70C, 4C, and area temperature (21C25C)) and thawed just on your day of assessment to measure the stability of SARS-CoV-2 IgG. In circumstances of insufficient quantity for an individual test to create all 10 aliquots, many patient specimens from the same test type had been pooled on the starting point. Testing of the initial examples was completed at the general public Health Lab, Alberta Accuracy Laboratories (Edmonton, Alberta, Canada). Desk 1 Serological assays utilized and their industrial details.
AllTest COVID-19 IgG Fast Check CassetteQualitativeIgGNoHangzhou Alltest Biotech, Hangzhou, ChinaArchitect SARS-CoV-2 IgGQualitativeIgG(focus on: nucleocapsid proteins)Yes;S/C??1.40 regarded positiveAbbott Laboratories, Chicago, USAcPass Surrogate Virus Neutralization Check (sVNT) KitQuantitativeNeutralizing antibodiesYes;% inhibitionGenScript Biotech, Piscataway, USAElecsys Anti-SARS-CoV-2QualitativeTotal (IgM+IgG)(focus on: nucleocapsid proteins)Yes;COI 1.0 regarded positiveRoche, Basel, SwitzerlandElecsys Anti-SARS-CoV-2 SQuantitativeTotal(IgM+IgG)(focus on: spike protein)Yes; 0.8?U/mL reactiveRoche, Basel, SwitzerlandLiaison SARS-CoV-2 S1/S2 IgGQualitativeIgG(focus on: spike proteins)Yes;15.0 AU/mL considered positive.Diasorin, Saluggia, ItalyStandard Q COVID-19 IgM/IgG ComboQualitativeIgM?+?IgGNoSD Biosensor, Suwon-si, South KoraWantai SARS-COV-2 Stomach ELISAQualitativeTotal (IgM+IgG)Yes;A/CO 1.0 considered positive.Beijing Wantai Biological, Beijing, China Open up in another screen Abbreviations: A/CO C absorbance over cut-off; AU/mL C arbitrary systems per mL; COI C cut-off index; S/C C.