The Centers for Disease Control and Prevention (CDC) algorithm for detecting presence of serum antibodies against Middle East Respiratory Syndrome coronavirus (MERS-CoV) in subjects with potential infections with the virus has included screening by indirect ELISA against recombinant nucleocapsid (N) protein and confirmation by immunofluorescent staining of infected monolayers and/or microneutralization titration. Other international groups include indirect ELISA assays using the spike (S) protein, as part of their serological determinations. In the current study, we describe development and validation of an indirect MERS-CoV S ELISA to be used as part of our serological determination for evidence of previous exposure to the virus.