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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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]