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Porcine coronaviruses (CoVs) are major viral infectious diseases of swine.Examples of porcine CoVs include porcine transmissible gastroenteritis coronavirus (TGEV), porcine epidemic diarrhea virus (PEDV), and porcine respiratory coronavirus (PRCV).In February 2014, another porcine CoV, porcine deltacoronavirus (PdCV), emerged in Ohio and Indiana and subsequently spread rapidly across the United States and Canada,causing significant economic losses.The Deltacoronavirus genus has been only recently defined by genomic sequence analysis of both pig and avian isolates.Since 2009, avian deltacoronaviruses have been detected in a wide range of domestic and wild birds.The porcine deltacoronaviruses (PdCV) Hong Kong (HK) strains HKU15-155 and HKU15-44 were recently detected in rectal swabs from pigs.The potential of the HKU15-155 and HKU15-44 PdCVs to cause significant clinical disease in swine is not known.In mid-January 2014, PdCV was identified in fatal cases of PEDV-negative diarrhea in Ohio piglets.Field reports document a history and clinical presentation (vomiting, diarrhea, and dehydration) typical of TGEV and PEDV;like for the other swine enteric CoVs, morbidity and mortality rates at PdCV-infected farms are high.In some instances, PdCV is the only virus recovered from these diarrhea outbreaks;in others, it may be present as a coinfection with PEDV.Recently, porcine deltacoronavirus (PDCoV) has been proven to be associated with enteric disease in piglets.Diagnostic tools for serological survey of PDCoV remains still the developing stage when compared with other porcine coroaviruses.In our study, an indirect ELISA (rPDCoV-N-ELISA) was developed for detection of antibodies against PDCoV by using recombinant nucleocapsid (N) protein with His-tag as antigen.In rPDCoV-N-ELISA, the recombinant diagnostic antigen showed no cross-reaction with antisera against porcine epidemic diarrhea virus (PEDV), swine transmissible gastroenteritis virus (TGEV), porcine rotavirus (PRoV), classical swine fever virus (CSFV), porcine circovirus-2 (PCV-2), porcine pseudorabies virus (PRV), and porcine reproductive and respiratory syndrome virus (PRRSV).Detection of the field samples indicated that the rPDCoV-N-ELISA would have a potential use for serum epidemiological investigation of PDCoV.