BOSTON: Scientists have found evidence of lower than expected transmission of protective antibodies against the novel coronavirus across the placenta of mothers infected in the third trimester, findings shedding light on critical windows in pregnancy that may be most desirable for vaccination .
According to the researchers, including those at Massachusetts General Hospital (MGH) in the US, the findings could be explained by a process by which the carbohydrate molecules in the body change antibodies after they are produced.
They explained that altered carbohydrate attachments to the coronavirus-specific antibodies – a process called glycosylation – may be the cause of the decreased transmission from mother to fetus.
In the study, published in the journal Cell, the scientists compared maternal antibodies to flu (influenza), whooping cough (pertussis) and the new coronavirus – SARS-CoV-2 – and how these antibodies were transmitted across the placenta.
They found that influenza and pertussis specific antibodies were actively transferred in a relatively normal way.
In contrast, the researchers said that not only was the transfer of SARS-CoV-2 specific antibodies to the baby significantly reduced, but the transferred antibodies were less functional than those against influenza.
According to the scientists, the reduced transmission was only seen with infection in the third trimester.
The study found that carbohydrate attachments on SARS-CoV-2 specific antibodies in the mother’s blood were different from those on influenza and pertussis specific antibodies.
The researchers believe that this carbohydrate pattern may cause the COVID-specific antibodies to “stay stuck” in the mother’s circulation, rather than being transmitted across the placenta via receptors for placental antibodies.
However, the scientists said that a certain increase in the total maternal antibodies induced by viral infection helped to partially overcome the problem and facilitate the transfer of some functional antibodies from mother to fetus.
Higher placental expression of a receptor that attracts the carbohydrate pattern on the SARS-CoV-2 specific antibodies also helped, the study said.
Based on the analysis, the scientists said some of the antibodies that transferred the best were also the most functional, activating the immune system’s natural killer cells that could help the newborn fight the virus if exposed.
The researchers believe the findings have implications for the design of new SARS-CoV-2 vaccine candidates for pregnant women.
“Vaccine regimens capable of stimulating high levels of the COVID-specific antibodies with glycosylation patterns favoring the placenta for selective transmission to the fetus may lead to better protection of neonates and infants,” says co-author Andrea Edlow , a medicine for mother and child. specialist at Massachusetts General Hospital.
The scientists said the study results may point to critical periods in pregnancy that are most desirable for vaccination to optimize protection for both the mother and her child.
According to the researchers, including those at Massachusetts General Hospital (MGH) in the US, the findings could be explained by a process by which the carbohydrate molecules in the body change antibodies after they are produced.
They explained that altered carbohydrate attachments to the coronavirus-specific antibodies – a process called glycosylation – may be the cause of the decreased transmission from mother to fetus.
In the study, published in the journal Cell, the scientists compared maternal antibodies to flu (influenza), whooping cough (pertussis) and the new coronavirus – SARS-CoV-2 – and how these antibodies were transmitted across the placenta.
They found that influenza and pertussis specific antibodies were actively transferred in a relatively normal way.
In contrast, the researchers said that not only was the transfer of SARS-CoV-2 specific antibodies to the baby significantly reduced, but the transferred antibodies were less functional than those against influenza.
According to the scientists, the reduced transmission was only seen with infection in the third trimester.
The study found that carbohydrate attachments on SARS-CoV-2 specific antibodies in the mother’s blood were different from those on influenza and pertussis specific antibodies.
The researchers believe that this carbohydrate pattern may cause the COVID-specific antibodies to “stay stuck” in the mother’s circulation, rather than being transmitted across the placenta via receptors for placental antibodies.
However, the scientists said that a certain increase in the total maternal antibodies induced by viral infection helped to partially overcome the problem and facilitate the transfer of some functional antibodies from mother to fetus.
Higher placental expression of a receptor that attracts the carbohydrate pattern on the SARS-CoV-2 specific antibodies also helped, the study said.
Based on the analysis, the scientists said some of the antibodies that transferred the best were also the most functional, activating the immune system’s natural killer cells that could help the newborn fight the virus if exposed.
The researchers believe the findings have implications for the design of new SARS-CoV-2 vaccine candidates for pregnant women.
“Vaccine regimens capable of stimulating high levels of the COVID-specific antibodies with glycosylation patterns favoring the placenta for selective transmission to the fetus may lead to better protection of neonates and infants,” says co-author Andrea Edlow , a medicine for mother and child. specialist at Massachusetts General Hospital.
The scientists said the study results may point to critical periods in pregnancy that are most desirable for vaccination to optimize protection for both the mother and her child.