Development of serological detection assays for human coronavirus HKU1 infection and its application

<p><b>OBJECTIVE</b>To express the nuclear capsid protein (N protein) and the spike protein (S protein) of HCoV-HKU1, and to develop the corresponding serum assay for antibody detection.</p><p><b>METHODS</b>The N protein of HCoV-HKU1 was expressed in E. Coli, anti-N antibody assay was established using Western Blotting with turn-based membrane. HCoV-HKU1 S protein was constructed in the eukaryotic expression plasmids, and confirmed by Western Blotting, S antibody assay was established using indirect immunofluorescence assay (IFA). We analyzed anti-S and anti-N antibody among 100 normal adult serum.</p><p><b>RESULTS</b>Expression of S and N protein were confirmed; 100 normal adult serum were analyzed using the established serological detection assay, in which HCoV-HKU1 S antibody positive rate was 47%, N antibody positive rate was 48%, Both S and N antibodies positive were 21%, Both S and N antibodies negative were 22%. Co-detection S and N antibody was achieved 74% positive rate.</p><p><b>CONCLUSION</b>The methods we established here could be used for serological analysis of HCoV-HKU1. Either detection of HCoV-HKU1 S or N antibodies achieved good results. Higher positive detection rate of anti-S or anti-N antibody was found in the normal adults.</p>