ABSTRACT
Serological tests developed for COVID-19 diagnostic are based on antibodies specific for SARS-CoV-2 antigens. Most of the antigens consist of a fragment or a whole amino acid sequence of the nucleocapsid or spike proteins. We evaluated a chimeric recombinant protein as an antigen in an ELISA test, using the most conserved and hydrophilic portions of the S1-subunit of the S and Nucleocapsid (N) proteins. These proteins, individually, indicated a suitable sensitivity of 93.6 and 100% and a specificity of 94.5 and 91.3%, respectively. However, our study with the chimera containing S1 and N proteins of SARS-CoV-2 suggested that the recombinant protein could better balance both the sensitivity (95.7%) and the specificity (95.5%) of the serological assay when comparing with the ELISA test using the antigens N and S1, individually. Accordingly, the chimera showed a high area under the ROC curve of 0.98 (CI 95% 0.958-1). Thus, our chimeric approach could be used to assess the natural exposure against SARS-CoV-2 virus over time, however, other tests will be necessary to better understand the behaviour of the chimera in samples from people with different vaccination doses and/or infected with different variants of the virus.
ABSTRACT
The present study investigated a SARS-CoV-2 infection in placenta and fetal samples from an early pregnancy miscarriage in Midwest Brazil. The Gamma variant was isolated and fully sequenced from the placenta sample, but not from fetal samples. Our findings highlight potential adverse perinatal outcomes caused by SARS-CoV-2 Gamma infection during pregnancy.