Seroprevalence of Anti-Mers-CoV IgG in two groups of Qatar population: Blood donors and case contacts

Abstract

Since its first isolation in September 2012, Middle East respiratory syndrome coronavirus (MERS-CoV) has diffused across 27 countries infecting more than 1910 individuals with a high case fatality rate. However, MERS-CoV has also been reported to be asymptomatic or to cause influenza-like mild illnesses. In the absence of clear epidemiological view, cross-sectional MERS-CoV antibody surveillances in human populations are of global concern. In this study, we present a comparative serological screening of 4719 blood donors, 135 baseline case contacts and 4 MERS-CoV confirmed patients for the presence of anti-MERS-CoV IgG. Methods: Samples were initially screened using MERS-CoV recombinant spike protein Enzyme linked immunoassay (rELISA) from Euroimmune, Germany. To confirm rELISA results, farther serological testing has been performed for borderline and reactive anti-MERS-CoV IgG samples by indirect immunofluorescent test (full virus IIFT) IgG/M, recombinant spike protein indirect immunofluorescent assay IgG (rIIFA) and pseudovirus neutralizing assay (ppNT). To access cross reactivity, borderline and reactive samples were also tested for presence of IgG to other human coronaviruses (HCoV) using IIFT, rIIFA and/ or in house rELISA. Results: rELISA yielded 3 borderlines (all donors) and 12 reactive (7 donors, 1 case contact and 4 samples collected from 3 MERS-CoV confirmed patients) anti-MERS-CoV IgG results. However, IIFT IgG confirmed only 5 reactive rELISA results (2 blood donors and 3 patients; the reactive case contact was not sufficient to be tested by IIFT IgG). Yet, r-IIFA and ppNT only confirmed the presence of specific anti-MERS-CoV antibodies in patients’ samples. Interestingly, all borderline and reactive tested samples showed reactive titers against recombinant spike proteins of other HCoV. Conclusion: Our findings suggest that MERS-CoV is not heavily circulated among the population of Qatar. This study provides an insight about the epidemiological view for MERS-CoV in Qatar population. It also provides a performance evaluation for the available serologic tests for MERS-CoV in a view of serologic status to other human coronaviruses.