BOSTON: Scientists have found evidence of less than expected transfer of protective antibodies against the new coronavirus across the placenta of infected mothers in the third trimester, findings that shed light on critical pregnancy windows that may be more desirable for vaccination.
According to the researchers, including those at Massachusetts General Hospital (MGH) in the United States, the findings can be explained by a process in which the carbohydrate molecules in the body alter antibodies after they are produced.
They explained that altered carbohydrate attachments to specific coronavirus antibodies – a process called glycosylation – may be to blame for the reduced transfer from the mother to the fetus.
In the study, published in the journal Cell, scientists compared maternal antibodies against influenza (influenza), whooping cough (whooping cough) and the new coronavirus – SARS-CoV-2 – and how these antibodies were transferred across the placenta.
They found that antibodies specific to influenza and pertussis were actively transferred in a relatively normal manner.
In contrast, the researchers said that the transfer of SARS-CoV-2-specific antibodies to the baby was not only significantly reduced, but the transferred antibodies were less functional than those against influenza.
According to the scientists, the reduction in transfer was only seen in the infection of the third trimester.
The study found that carbohydrate attachments in SARS-CoV-2 specific antibodies in maternal blood were different from those seen in specific antibodies for influenza and pertussis.
The researchers believe that this pattern of carbohydrates may cause specific antibodies in COVID to become “trapped” in the maternal circulation, rather than being transferred across the placenta via placental antibody receptors.
However, the scientists said that some increases in the total maternal antibodies induced by the viral infection helped to partially overcome the problem and facilitate the transfer of some functional antibodies from the mother to the fetus.
Greater placental expression of a receptor that attracts the carbohydrate pattern in SARS-CoV-2 specific antibodies also helped, the study noted.
Based on the analysis, the scientists said some of the antibodies that transferred best were also the most functional, activating the natural killer cells of the immune system 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 driving high levels of specific COVID antibodies with glycosylation patterns favored by the placenta for selective transfer to the fetus can lead to better neonatal and infant protection,” says study co-author Andrea Edlow, a maternal drug specialist in Massachusetts General Hospital.
Scientists said the results of the study may point to critical windows in pregnancy that may be more desirable for vaccination to optimize protection for the mother and her child.
According to the researchers, including those at Massachusetts General Hospital (MGH) in the United States, the findings can be explained by a process in which the carbohydrate molecules in the body alter antibodies after they are produced.
They explained that altered carbohydrate attachments to specific coronavirus antibodies – a process called glycosylation – may be to blame for the reduced transfer from the mother to the fetus.
In the study, published in the journal Cell, scientists compared maternal antibodies against influenza (influenza), whooping cough (whooping cough) and the new coronavirus – SARS-CoV-2 – and how these antibodies were transferred across the placenta.
They found that antibodies specific to influenza and pertussis were actively transferred in a relatively normal manner.
In contrast, the researchers said that the transfer of SARS-CoV-2-specific antibodies to the baby was not only significantly reduced, but the transferred antibodies were less functional than those against influenza.
According to the scientists, the reduction in transfer was only seen in the infection of the third trimester.
The study found that carbohydrate attachments in SARS-CoV-2 specific antibodies in maternal blood were different from those seen in specific antibodies for influenza and pertussis.
The researchers believe that this pattern of carbohydrates may cause specific antibodies in COVID to become “trapped” in the maternal circulation, rather than being transferred across the placenta via placental antibody receptors.
However, the scientists said that some increases in the total maternal antibodies induced by the viral infection helped to partially overcome the problem and facilitate the transfer of some functional antibodies from the mother to the fetus.
Greater placental expression of a receptor that attracts the carbohydrate pattern in SARS-CoV-2 specific antibodies also helped, the study noted.
Based on the analysis, the scientists said some of the antibodies that transferred best were also the most functional, activating the natural killer cells of the immune system 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 driving high levels of specific COVID antibodies with glycosylation patterns favored by the placenta for selective transfer to the fetus can lead to better neonatal and infant protection,” says study co-author Andrea Edlow, a maternal drug specialist in Massachusetts General Hospital.
Scientists said the results of the study may point to critical windows in pregnancy that may be more desirable for vaccination to optimize protection for the mother and her child.