Figure 2From: First infection by all four non-severe acute respiratory syndrome human coronaviruses takes place during childhood Representative IFA for detection of anti-S antibodies of non-SARS HCoVs in human serum. A, 229E-S expression plasmid; B, OC43-S expression plasmid; C, HKU1-S expression plasmid; D, NL63-S expression plasmid; control, mock plasmid pVRC-8304.Back to article page