Research led by investigators at Massachusetts General Hospital (MGH) indicated the severe risk of Covid-19 followed SARS-CoV-2 infection into pregnant women and newborns.
The study published in the publication Cell reveals lower than the expected transfer of protective SARS-CoV-2 antibodies via the placenta from mothers who are infected in the third trimester. The cause could also be alterations to these antibodies after they’re produced–a process called glycosylation.
The results expand on the team’s recent findings published in JAMA Network Open that pregnant women with Covid-19 pass no SARS-CoV-2 virus, but also slightly low levels of antibodies against it, to newborns.
For this latest study, the scientists compared maternal antibodies against the flu (influenza), whooping cough (pertussis), and SARS-CoV-2, and how these antibodies transferred across the placenta.Influenza- and pertussis-specific antibodies were actively transferred in a slightly normal fashion. In contrast, transfer of SARS-CoV-2-specific antibodies to the baby was once not only significantly reduced, but the antibodies transferred were less functional than the antibodies against influenza. The reduced transfer was once only observed in third-trimester infection.
The scientists found that altered attachments of carbohydrates to the SARS-CoV-2-specific antibodies — a process called glycosylation — could also be to blame for this reduced transfer from mother to fetus in the third trimester.
The carbohydrate attachments on SARS-CoV-2-specific antibodies in maternal blood were different than those seen on influenza- and pertussis-specific antibodies. This carbohydrate sample may cause the Covid-specific antibodies to be “stuck” in the maternal circulation, quite than transferred across the placenta via placental antibody receptors.
Infection-induced increases in complete maternal antibodies, in addition to higher placental expression of an antibody receptor that attracts the carbohydrate sample on the SARS-CoV-2-specific antibodies, helped to partially overcome the problem and facilitate the transfer of a few functional antibodies from mother to fetus.
Interestingly, one of the antibodies that transferred the most efficient were also the most functional, activating natural killer cells that could help the newborn fight the virus whether exposed.
The findings have implications for the design of vaccines against SARS-CoV-2 for pregnant women.”Vaccine regimens ready to drive high levels of the Covid-specific antibodies with glycosylation patterns favoured by the placenta for selective transfer to the fetus may lead to better neonatal and infant protection,” said co-senior creator Andrea Edlow, MD, MSc, a maternal-fetal medicine specialist at MGH and an assistant professor of Obstetrics, Gynecology, and Reproductive Biology at Harvard Medical School.
“We are beginning to define the rules of placental antibody transfer of SARS-CoV-2 for the first actual time — catalyzing our ability to rationally design vaccines to give protection to pregnant women and their newborns,” Co-senior creator and Core Member at the Ragon Institute of MGH, MIT and Harvard, Galit Alter, PhD, said.
Moreover, understanding how antibody transfer varies by trimester may point to critical windows in pregnancy that can be most desirable for vaccination to optimize protection for both the mother and her infant.
(This story has been published from a wire agency feed without modifications to the text.)
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