Objective To describe the profile and specificity of maternal and neonatal cord-blood antibody profile in response SARS-CoV-2 virus exposure Methods This is a Prospective cohort study of delivering patients at Thomas Jefferson University Hospital from April 2020-February 2021. Primary objective was to describe unique maternal and fetal antibody epitope titers and specificity in those patients with COVID-19 history. Serologic profile assessed with a multiplex platform. Antigens used were: HA-trimer Influenza A (Hong Kong H3), spike trimers for SARS-CoV-2, SARS-CoV-1, MERS-CoV, and betacoronaviruses HKU-1 and OC43, as well as the spike N-terminal domain (NTD), spike receptor binding domain (RBD), and nucleocapsid protein (N; full length) for SARS-CoV-2. Results 112 maternal samples and 101 maternal and cord blood pairs were analyzed. Thirty-seven had a known history of COVID-19 (positive PCR test) in the pregnancy and of those, 17 (47%) were diagnosed with COVID-19 within 30 days of delivery. Fifteen of remaining seventy-six (20%) without a known diagnosis had positive maternal serology. For those with history of COVID-19 we identified robust IgG response in maternal blood to CoV2 nucleocapsid (N), spike (S) full-length and S (RBD) antigens with more modest responses to the S (NTD) antigen. By contrast, the maternal blood IgM response appeared more specific to S (full-length), than N, S (RBD) or S (NTD) epitopes. There were significantly higher maternal and cord blood IgG response not just to CoV2 spike (127.1-fold (SD 2.0, p < .00001)), but also CoV1 spike (21.1 fold higher, SD 1.8, p < .00001) and MERS spike (6.9 fold higher, SD 2.5, p < .00001). By contrast, maternal IgM responses were more specific to CoV2 spike (15.8-fold (SD 2.1, p < .00001)), but to a lesser degree for CoV1 (2.5-fold higher, SD 0.71, p < .00001), and no significant differences for MERS. Maternal and cord-blood IgG were highly correlated for both S and N (R2 = 0.96 and 0.94). Conclusions Placental transfer is efficient, with robust N and S responses. Both nucleocapsid and spike antibody responses should be studied for a better understanding of COVID-19 immunity. IgG antibodies are cross reactive with related CoV-1 and MERS spike epitopes while IgM, which cannot cross placenta to provide neonatal passive immunity, is more SARS CoV-2 specific. Neonatal cord blood may have significantly different fine-specificity than maternal blood, despite the high efficiency of IgG transfer.
Comprehensive Serological Profile and Specificity of Maternal and Neonatal Cord Blood SARS CoV-2 Antibodies