90 Placental transfer of SARS-CoV-2 specific antibodies from mothers to newborns

Estrada Trejo, Fatima A.; Pfalzgraf, Hadley; Arora, Avish; Mahant, Aakash Mahant; Herold, Betsy

Objective: Severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2), binds with its spike (S) protein to the human angiotensin converting enzyme 2 (ACE2) through its receptor-binding domain. S-specific antibodies (Abs) induce a robust immunologic response and several studies have shown that previously infected individuals have high titers of Abs against this protein. Placental transfer of Abs is generally dependent on the specific Abs concentration, subtype, Fc glycan profile, antigen specificity and gestational age. Given the novelty of this viral disease, little is known about the immunologic response of pregnant women to SARS-CoV-2. We aim to assess and quantify the transfer of S-specific Abs from mothers to infants, by using paired maternal and cord blood samples. Study Design: The concentration of S-specific IgG Abs was assayed by ELISA in plasma of previously recruited, SARS-CoV-2 seropositive pregnant women. Samples were collected from peripheral blood during admission for delivery and from cord blood at the time of delivery. Result(s): We enrolled 33 women in the study. Of these, 20/33 (60.6%) were diagnosed with SARS-CoV-2 infection at the time of admission for delivery, and 13/33 (39.4%) were diagnosed at least 7 days before delivery;17/33 (51.5%) were asymptomatic and 16/33 (48.5%) were symptomatic. There is transfer of S-specific IgG Abs through placenta. The concentration of S-specific Abs was slightly higher on log10 end point dilution for mothers that had tested positive at least 7 days before delivery when compared to those tested positive at time of delivery. The concentration of Abs for asymptomatic mothers was lower than for those that presented symptoms. These trends were also seen in newborns for each respective group. Conclusion(s): There is transfer of S-specific IgG Abs from mothers to newborns. Transfer appears to be dependent on timing of infection and severity of disease. Patients infected at an earlier gestational age and with clinical symptoms transfer more Abs to their newborns. Studies to examine the functionality of the Abs are in progress.Copyright © 2019