Detection of SARS-CoV-2 omicron variants by immunochromatographic kit.

An immunochromatographic kit using antibodies against recombinant N protein of an omicron B.1.1.529 of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) was developed to detect SARS-CoV-2 omicron variants. The kit detected omicron variants (BA.1.18, BA.1.1, BA.2, BA.2.12.1, BA.2.75, BA.4.1, BA.4.6, BE.1, BA.5.2.1, XE, BF.7, BF.7.4.1, XBB.1, XBB.1.5 and BQ.1.1) as well as Wuhan strain and a delta variant.

Antibodies against spike protein of SARS-CoV-2 variants in bovine whey IgG enriched fraction.

Bovine whey IgG enriched fraction contains IgG antibodies against bacterial and viral pathogens, including antibodies against the spike protein [amino acids (aa) 1-1274] of SARS-CoV-2 Wuhan strain (2019-nCoV WHU01). To date, 13 SARS-CoV-2 variants have been identified, including gamma, delta, kappa, and omicron, which contain 10, eight, seven, and over 30 mutations in the spike protein, respectively. We investigated whether bovine whey IgG enriched fraction contains antibodies against spike proteins of these variants, specifically recombinant partial length spike proteins (aa 177-512, aa 509-685, aa 177-324, aa 250-410 and aa 387-516) of these variants. Direct enzyme-linked immunosorbent assays revealed bovine whey IgG enriched fraction contained antibodies against all recombinant spike proteins of these variants with highest reactivity against aa 177-512 region of omicron spike protein. These results indicate bovine whey IgG enriched fraction contains antibodies against spike proteins of several SARS-CoV-2 variants, including omicron.

Correlation of COVID-19 Severity and Immunoglobulin Presence Against Spike and Nucleocapsid Proteins in SARS-CoV-2.

Data on the human immune response to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) proteins have been applied to vaccine development and diagnosing coronavirus disease 2019 (COVID-19), but little research has been done on the relationship between the human immune response and COVID-19 severity. We herein sought to determine whether there is a correlation between the immunoglobulin level and COVID-19 severity. Clinical samples were collected from 102 patients with COVID-19. Of these, 65 and 37 patients had mild and severe symptoms, respectively. An enzyme-linked immunosorbent assay using the recombinant SARS-CoV-2 nucleocapsid (N) protein, spike (S) protein, and synthetic peptides covering N and S as antigens was performed to measure the IgM and IgG levels. The correlation between the immunoglobulin level and COVID-19 severity was then analyzed. A significant difference in the level of IgG antibodies against N and of IgM antibodies against the receptor binding domain of the S protein was observed between patients with nonsevere and severe COVID-19 symptoms, and the level of IgG antibodies against N was found to be higher in patients with severe symptoms whereas the level of IgM antibodies against the S peptides was higher in patients with nonsevere symptoms. The level of specific antibodies against SARS-CoV-2 structural proteins might correlate with COVID-19 severity. If so, this fact may be useful for predicting the prognosis of the disease and in determining the appropriate treatment with greater precision.

Assessment of an immunochromatographic kit for detection of severe acute respiratory syndrome coronavirus 2 and influenza viruses.

An immunochromatographic kit was developed to detect severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and influenza viruses (A and B) on two detection positions of a single strip. The sensitivity and specificity for SARS-CoV-2 were 97.4 % and 100 %, respectively, and those for influenza viruses were 100 %, respectively.

Development of an immunochromatographic kit to detect severe acute respiratory syndrome coronavirus 2.

BACKGROUND: The novel severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) is responsible for the worldwide coronavirus disease-19 (COVID-19) pandemic, starting in late 2019. The standard diagnostic methods to detect SARS-CoV-2 are PCR-based genetic assays. Antigen-antibody-based immunochromatographic assays are alternative methods of detecting this virus. Rapid diagnosis kits to detect SARS-CoV-2 are urgently needed. STUDY DESIGN: Three monoclonal antibodies against SARS-CoV-2 nucleocapsid (N) protein were used to develop an antigen-antibody-based immunochromatographic kit to detect SARS-CoV-2. These assays were evaluated using　 nasopharyngeal swab specimens collected from patients suspected of having COVID-19. RESULTS: These assays detected recombinant SARS-CoV-2 N protein at concentrations >0.2 ng/mL within 10 min after protein loading, but did not detect the N proteins of Middle East respiratory syndrome coronavirus (MERS-CoV), human coronaviruses OC43 (HCoV-OC43) and 299E (HCoV-229E) and other pathogens causing respiratory infections. Nasopharyngeal swab specimens obtained 1～3, 4～9, and ≥ 10 days after symptom onset from COVID-19 patients diagnosed by RT-PCR showed positivity rates of 100 %, >80 %, and <30 %, respectively. CONCLUSIONS: Kits using this immunochromatographic assay may be a rapid and useful tool for point-of-care diagnosis of COVID-19 when samples are obtained from patients 1～9 days after symptom onset.

Presence of antibodies against SARS-CoV-2 spike protein in bovine whey IgG enriched fraction.

Bovine whey IgG enriched fraction contains antibodies against various human bacterial pathogens. It contains antibodies against some viral antigens, including human respiratory syncytial virus and influenza virus. We investigated whether the IgG enriched fraction has cross-reactivity with IgG antibodies against SARS-CoV-2 spike (S) and nucleocapsid (N) proteins. The full-length and partial-length SARS-CoV-2 S, N, a recombinant protein of the receptor binding domain (RBD) and nine peptides covering the receptor binding motif (RBM) of S were prepared. Direct enzyme-linked immunosorbent assays were conducted using these recombinant proteins and peptides as coating antigens and revealed the IgG enriched fraction contained antibodies against partial-length S [amino acids (aa) 177-512, 288-512, 348-578, 387-516 and 408-664], full-length N (aa 1-419) and partial-length N (aa 1-120, 111-220, 1-220 and 210-419), two RBD peptides, covering aa 427-446 and 502-520 of S, and recombinant RBD of S. These results indicate IgG enriched fraction contains antibodies against SARS-CoV-2.

Assessment of a newly developed immunochromatographic assay for NDM-type metallo-ß-lactamase producing Gram-negative pathogens in Myanmar.

BACKGROUND: To detect carbapenemase-producing Gram-negative bacteria in bacterial laboratories at medical settings, a new immunochromatographic assay for New Delhi metallo-ß-lactamases (NDMs) was developed. METHODS: The immunochromatographic assay for New Delhi metallo-ß-lactamases producers was developed using rat monoclonal antibodies against NDMs. The assessment was performed using 350 isolates of Gram-negative bacteria, including Acinetobacter baumannii (51 isolates), Enterobacteriaceae (163 isolates), and Pseudomonas aeruginosa (136 isolates) obtained from 2015 to 2017 in medical settings in Myanmar. Of them, 302 isolates were resistant to carbapenems, including imipenem and/or meropenem. The blaNDM genes were identified by PCR and sequencing. RESULTS: Of the 350 clinical isolates tested, 164 (46.9%) (60 isolates of Escherichia coli, 51 isolates of Klebsiella pneumoniae, 25 isolates of Enterobacter cloacae, 23 isolates of P. aeruginosa, and 5 isolates of A. baumannii) were positive on this assay, and all the positive isolates harbored genes encoding NDM-1, - 4, - 5 and - 7. The remaining 186 (53.1%) isolates negative on the assay did not harbor genes encoding NDMs. The assay had a specificity of 100% and a sensitivity of 100%. The assessment revealed that more than 90% of carbapenem-resistant Enterobacteriaceae produced NDMs. CONCLUSIONS: The immunochromatographic assay is an easy-to-use and reliable kit for detection of NDMs-producing Gram-negative bacteria. The assay revealed that NDM-producing Enterobacteriaceae isolates are wide-spread in medical settings in Myanmar.