{Reference Type}: Journal Article
{Title}: Salivary IgA and vimentin differentiate in vitro SARS-CoV-2 infection: A study of 290 convalescent COVID-19 patients.
{Author}: Ellis S;Way R;Nel M;Burleigh A;Doykov I;Kembou-Ringert J;Woodall M;Masonou T;Case KM;Ortez AT;McHugh TD;Casal A;McCoy LE;Murdan S;Hynds RE;Gilmour KC;Grandjean L;Cortina-Borja M;Heywood WE;Mills K;Smith CM;
{Journal}: Mucosal Immunol
{Volume}: 17
{Issue}: 1
{Year}: 2024 Feb 24
{Factor}: 8.701
{DOI}: 10.1016/j.mucimm.2023.11.007
{Abstract}: SARS-CoV-2 initially infects cells in the nasopharynx and oral cavity. The immune system at these mucosal sites plays a crucial role in minimizing viral transmission and infection. To develop new strategies for preventing SARS-CoV-2 infection, this study aimed to identify proteins that protect against viral infection in saliva. We collected 551 saliva samples from 290 healthcare workers who had tested positive for COVID-19, before vaccination, between June and December 2020. The samples were categorized based on their ability to block or enhance infection using in vitro assays. Mass spectrometry and enzyme-linked immunosorbent assay experiments were used to identify and measure the abundance of proteins that specifically bind to SARS-CoV-2 antigens. Immunoglobulin (Ig)A specific to SARS-CoV-2 antigens was detectable in over 83% of the convalescent saliva samples. We found that concentrations of anti-receptor-binding domain IgA >500 pg/µg total protein in saliva correlate with reduced viral infectivity in vitro. However, there is a dissociation between the salivary IgA response to SARS-CoV-2, and systemic IgG titers in convalescent COVID-19 patients. Then, using an innovative technique known as spike-baited mass spectrometry, we identified novel spike-binding proteins in saliva, most notably vimentin, which correlated with increased viral infectivity in vitro and could serve as a therapeutic target against COVID-19.