“…Recombinant staphylococcal protein A and soybean trypsin inhibitor (STI) were purchased from Sigma-Aldrich (St. Louis, MO, USA). In the current study, a rabbit antiserum obtained earlier [18,19] was used. The ready-to-use peroxidase substrate solution based on 3,3 ,5,5 -tetramethylbenzidine (TMB) was provided by Immunotech (Moscow, Russia).…”