Evasion of COVID-19 vaccine-medicated mucosal immunity by SARS-CoV-2 Omicron

NELF was carefully collected using hydroxylated polyvinyl acetate (PVA) sponges. These sponges were inserted within the inferior turbinate and the nasal septum and left in situ for approximately 15 minutes till they swelled, then softly withdrawn and kept in a 50 ml Falcon tube with 2 ml of saline solution. Simple pressure was used to remove the fluid (nasal secretions+saline) from the sponge, which was then aliquoted and stored at -70°C for further examination. The VPLEX® SARS-CoV-2 Panel was used to assess IgG and IgA targeting the S of the SARS-CoV-2 Omicron, Delta variants, and ancestor strain. Further, the V-PLEX® Isotyping Panel 1 Human/NHP Kit was used to determine total IgG and IgA levels. Nasal secretions were diluted 10-time before being tested for S-specific and overall IgG and IgA. The V-PLEX® Sector Imager 2400 plate reader was used to collect data, which was then processed using Discovery Workbench 3.0 software. The ability of NELF antibodies to hinder the adherence of a soluble ACE2 to S of the SARS-CoV-2 Omicron, Delta variants, and the ancestral strain was tested by the multiplex V-PLEX® SARS-CoV-2 Panel 13 ACE2 Kit. Before assessing for binding attenuation, NELF was diluted 10-time. As mentioned above, the data was collected and analyzed using the V-PLEX® Sector Imager 2400 plate reader and the Discovery Workbench 3·0 software, respectively.