Sensitive Detection of SARS-CoV-2-Specific Antibodies in Dried Blood Spot Samples.
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ABSTRACT:
SUBMITTER: Morley GL
PROVIDER: S-EPMC7706975 | biostudies-literature | 2020 Dec
REPOSITORIES: biostudies-literature
Publications
Sensitive Detection of SARS-CoV-2-Specific Antibodies in Dried Blood Spot Samples.
Morley Gabriella L GL Taylor Stephen S Jossi Sian S Perez-Toledo Marisol M Faustini Sian E SE Marcial-Juarez Edith E Shields Adrian M AM Goodall Margaret M Allen Joel D JD Watanabe Yasunori Y Newby Maddy L ML Crispin Max M Drayson Mark T MT Cunningham Adam F AF Richter Alex G AG O'Shea Matthew K MK
Emerging infectious diseases 20200924 12
Dried blood spot (DBS) samples can be used for the detection of severe acute respiratory syndrome coronavirus 2 spike antibodies. DBS sampling is comparable to matched serum samples with a relative 98.1% sensitivity and 100% specificity. Thus, DBS sampling offers an alternative for population-wide serologic testing in the coronavirus pandemic. ...[more]
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Project description:A homogeneous PCR-based assay for sensitive and specific detection of antibodies in serum or dried blood spots (DBS) is presented and the method is used to monitor individuals infected with or vaccinated against SARS-CoV-2. Detection probes were prepared by conjugating the recombinant spike protein subunit 1 (S1), containing the receptor binding domain (RBD) of SARS-CoV-2, to each of a pair of specific oligonucleotides. The same was done for the nucleocapsid protein (NP). Upon incubation with serum or DBS samples, the bi- or multivalency of the antibodies (IgG, IgA or IgM) brings pairs of viral proteins with their conjugated oligonucleotides in proximity, allowing the antibodies to be detected by a modified proximity extension assay (PEA). Anti-S1 and anti-NP antibodies could be detected simultaneously from one incubation reaction. This Antibody PEA (AbPEA) test uses only 1 µl of neat or up to 100,000-fold diluted serum or one ø1.2 mm disc cut from a DBS. All 100 investigated sera and 21 DBS collected prior to the COVID-19 outbreak were negative, demonstrating a 100% specificity. The area under the curve, as evaluated by Receiver Operating Characteristic (ROC) analysis reached 0.998 (95%CI: 0.993-1) for samples taken from 11 days after symptoms onset. The kinetics of antibody responses were monitored after a first and second vaccination using serially collected DBS from 14 individuals. AbPEA offers highly specific and sensitive solution-phase antibody detection without requirement for secondary antibodies, no elution step when using DBS sample in a simple procedure that lends itself to multiplex survey of antibody responses.
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Project description:Numerous sero-epidemiological studies have been initiated to investigate the spread and dynamics of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). To address the concomitant need for serological high-throughput assays, a bead-based multiplex serology assay, specific for SARS-CoV-2, had been developed. SARS-CoV-2 serolomics allows for measuring antibody responses to almost the entire SARS-CoV-2 proteome in up to 2000 serum samples per day. To enlarge the pool of eligible sample collection methods, we here test the compatibility of serolomics with dried blood spot (DBS)-derived eluates. Antibody levels of nine SARS-CoV-2 antigens, including the nucleocapsid (N) and receptor-binding domain of the spike protein (S1-RBD), were measured in 142 paired DBS and serum samples. The numeric correlation between the two sample types was high, with a Pearson's r of 0.88 for both S1-RBD and N and intraclass correlation coefficients of 0.93 and 0.92, respectively. Systematically reduced antibody levels in DBS eluates were compensated by lowering the cutoffs for seropositivity accordingly. This enabled the concordant classification of SARS-CoV-2 seropositivity, without loss in sensitivity. Antibody levels against accessory SARS-CoV-2 antigens also showed a high concordance, demonstrating that DBS-derived eluates are eligible for SARS-CoV-2 serolomics. DBS cards facilitate the collection of blood samples, as they obviate the need for medically trained personnel and can be shipped at room temperature. In combination with SARS-CoV-2 serolomics, DBS cards enable powerful sero-epidemiological studies, thus allowing for the monitoring of patients and epidemiological analyses in resource-poor settings.
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Project description:We examined the usefulness of dried spot blood and saliva samples in SARS-CoV-2 antibody analyses. We analyzed 1231 self-collected dried spot blood and saliva samples from healthcare workers. Participants filled in a questionnaire on their COVID-19 exposures, infections, and vaccinations. Anti-SARS-CoV-2 IgG, IgA, and IgM levels were determined from both samples using the GSP/DELFIA method. The level of exposure was the strongest determinant of all blood antibody classes and saliva IgG, increasing as follows: (1) no exposure (healthy, non-vaccinated), (2) exposed, (3) former COVID-19 infection, (4) one vaccination, (5) two vaccinations, and (6) vaccination and former infection. While the blood IgG assay had a 99.5% sensitivity and 75.3% specificity to distinguish participants with two vaccinations from all other types of exposure, the corresponding percentages for saliva IgG were 85.3% and 65.7%. Both blood and saliva IgG-seropositivity proportions followed similar trends to the exposures reported in the questionnaires. Self-collected dry blood and saliva spot samples combined with the GSP/DELFIA technique comprise a valuable tool to investigate an individual's immune response to SARS-CoV-2 exposure or vaccination. Saliva IgG has high potential to monitor vaccination response wane, since the sample is non-invasive and easy to collect.
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| S-EPMC10000641 | biostudies-literature
Project description:The COVID-19 pandemic led to development of numerous serologic tests. To obviate the need for phlebotomy services, we validated dried blood spots (DBS) for anti-SARS-CoV-2 serologic testing. Immunoglobulins were extracted from 3 mm DBS punches and the extracts were analyzed using the Euroimmun anti-SARS-CoV-2 IgG ELISA. Various pre-analytical factors were studied. Results were favorable for DBS stored for at least 67 days at or below 37°C. Comparison between paired serum and DBS specimens tested by the Euroimmun ELISA showed 96.8% and 81.3% positive and negative agreement, respectively, indicating that confirmatory testing of positive Euroimmun results on DBS extracts is necessary to achieve clinical accuracy. Our findings suggest that any SARS-CoV-2 antibody assay that requires pre-dilution of serum is amenable to DBS as an alternate specimen type that is relatively low cost, self-collectable, stable, can be shipped by standard mail and could be used to establish the seroprevalence of large populations.
| S-EPMC8116316 | biostudies-literature
Project description:Dried blood spot samples (DBS) provide an alternative sample type to venous blood samples for antibody testing. DBS are used by NHS for diagnosing Hepatitis C and by Public Health England for large scale HIV and Hepatitis C serosurveillance; the applicability of DBS based approaches for SARS-CoV-2 antibody detection is uncertain. The study aimed to compare antibody detection in DBS eluates using the Roche Elecsys ® immunoassay with antibody detection in paired plasma samples, using the same assay. The study was in one Police and one Fire & Rescue facility in England; it comprised of 195 participants within a larger sample COVID-19 serodiagnostics study of keyworkers, EDSAB-HOME. Outcome measures were sensitivity and specificity of DBS (the index test) relative to plasma (the reference test), at an experimental cut-off; quality of DBS sample collected; estimates of relative sensitivity of DBS vs. plasma immunoassay in a larger population. 18/195 (9.2%) participants tested positive using plasma samples. DBS sample quality varied markedly by phlebotomist, and low sample volume significantly reduced immunoassay signals. Using an experimental cut-off, sensitivity and specificity of DBS were 89.0% (95% CI 67.2, 96.9%) and 100.0% (95% CI 97.9, 100%) respectively compared with using plasma. The limit of detection for DBS is about 30 times higher than for plasma. DBS use for SARS-CoV-2 serology, though feasible, is insensitive relative to immunoassays on plasma. Sample quality impacts on assay performance. Alternatives, including the collection of capillary blood samples, should be considered for screening programs.
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Project description:Dried blood spot (DBS) sampling is a minimally invasive method for specimen collection with potential multifaceted uses, particularly for serosurveillance of previous SARS-CoV-2 infection. In this study, we assessed DBS as a potential specimen type for assessing IgG and total (including IgG and IgM) antibodies to SARS-CoV-2 in vaccinated and naturally infected patients. Six candidate buffers were assessed for eluting blood from DBS cards. The study utilized one hundred and five paired plasma specimens and DBS specimens from prospectively collected SARS-CoV-2 vaccinated individuals, remnants from those with PCR confirmed SARS-CoV-2 infections, or remnants from those without history of infection or vaccination. All specimens were tested with the Siemens SARS-CoV-2 total assay (COV2T) or IgG assay (sCOVG). The lowest backgrounds were observed with water and PBS, and water was used for elution. Relative to plasma samples, DBS samples had a positive percent agreement (PPA) of 94.4% (95% CI: 94.9-100%) for COV2T and 79.2 (68.4-87.0) for sCOVG using the manufacturer's cutoff. The NPA was 100 % (87.1-100.0 and 85.13-100) for both assays. Dilution studies revealed 100% (95% CI: 90.8-100%) qualitative agreement between specimen types on the COV2T assay and 98.0% (88.0-99.9%) with the sCOVG using study defined cutoffs. DBS specimens demonstrated high PPA and NPA relative to plasma for SARS-CoV-2 serological testing. Our data support feasibility of DBS sampling for SARS-CoV-2 serological testing.
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Project description:In the earliest days of the COVID-19 pandemic, the collection of dried blood spots (DBS) enabled public health laboratories to undertake population-scale seroprevalence studies used to estimate rates of SARS-CoV-2 exposure. With SARS-CoV-2 seropositivity levels now estimated to exceed 94% in the United States, attention has turned to using DBS to assess neutralizing antibodies within cohorts of interest. With this goal in mind, we generated contrived DBS (cDBS) and whole blood-derived DBS from convalescent and vaccinated individuals and subjected DBS eluates to a battery of assays, including a SARS-CoV-2 multiplexed microsphere immunoassay (MIA), a receptor binding domain (RBD)-human ACE2 inhibition assay (iACE2), a cell-based pseudovirus neutralization assay, and real-time PCR-based surrogate neutralization assay (NAB-Sure). The DBS results were benchmarked against paired serum samples tested in a clinically validated SARS-CoV-2 plaque reduction neutralization titer (PRNT) assay. The results of an 8-plex MIA and NAB-Sure assays demonstrated highly significant correlations with PRNT values when evaluated with a panel of 86 paired serum-DBS samples. Both the MIA and NAB-Sure are adaptable to automated liquid handlers for high-throughput capacity. While neutralizing assays were limited to the ancestral SARS-CoV-2 WA1, this study nonetheless represents an important proof of concept demonstrating the potential utility of DBS as a biospecimen type for use in assessing immunity to SARS-CoV-2 at the community and population levels.IMPORTANCESARS-CoV-2 variants of concern continue to circulate globally and remain a serious health threat to large segments of the population. From a public health standpoint, identifying vulnerable communities based on immune status is critical in terms of vaccine booster recommendations. In this report, we investigated the utility of dried blood spots (DBS) as a biospecimen type from which to estimate SARS-CoV-2 neutralizing antibody titers. Using contrived and whole blood-derived DBS, we demonstrate that SARS-CoV-2 neutralizing antibodies are readily measurable in DBS eluates and correlate with plaque reduction neutralization titer (PRNT) values from paired serum samples. Moreover, several of the methods used to estimate SARS-CoV-2 neutralizing antibodies in DBS eluates are adaptable to high-throughput platforms.
| S-EPMC11619372 | biostudies-literature
Project description:BackgroundIn the earliest days of COVID-19 pandemic, the collection of dried blood spots (DBS) enabled public health laboratories to undertake population-scale seroprevalence studies to estimate rates of SARS-CoV-2 exposure. With SARS-CoV-2 seropositivity levels now estimated to exceed 94% in the United States, attention has turned to using DBS to assess functional (neutralizing) antibodies within cohorts of interest.MethodsContrived DBS eluates from convalescent, fully vaccinated and pre-COVID-19 serum samples were evaluated in SARS-CoV-2 plaque reduction neutralization titer (PRNT) assays, a SARS-CoV-2 specific 8-plex microsphere immunoassay, a cell-based pseudovirus assay, and two different spike-ACE2 inhibition assays, an in-house Luminex-based RBD-ACE2 inhibition assay and a commercial real-time PCR-based inhibition assay (NAB-Sure™).ResultsDBS eluates from convalescent individuals were compatible with the spike-ACE2 inhibition assays, but not cell-based pseudovirus assays or PRNT. However, the insensitivity of cell-based pseudovirus assays was overcome with DBS eluates from vaccinated individuals with high SARS-CoV-2 antibody titers.ConclusionSARS-CoV-2 neutralizing titers can be derived with confidence from DBS eluates, thereby opening the door to the use of these biospecimens for the analysis of vulnerable populations and normally hard to reach communities.
| S-EPMC10983952 | biostudies-literature