“…The serum samples were tested for the presence of IgG antibodies reactive with S1 antigens against MERS-CoV (residues 1-747), severe acute respiratory syndrome CoV (residues 1-676), and human CoV OC43 (residues 1-760) by using extensively validated protein-microarray technology, as described (2,3,6,11). Results were expressed as relative mean fluorescent intensity (RFU) for each set of quadruplicate spots of antigen, with a cutoff of 4,000 RFU as used by Meyer et al (6).…”