Heel-prick blood samples from newborns can be used to measure antibodies against Group B Streptococcus, according to a new study from Aarhus University. In the longer term, the method could contribute to the development of vaccines designed to protect infants against serious infections.
A few days after birth, all newborns in Denmark have a small blood sample taken from their heel. Among other purposes, the sample is used to screen babies for a wide range of rare congenital diseases.
A new study now shows that these blood samples can also be used to measure how many antibodies against Group B Streptococcus, also known as GBS, a baby has received from its mother during pregnancy.
GBS can cause serious infections in newborns, which is why researchers are working to identify ways of protecting infants against the bacterium. One possible approach is to vaccinate the mother during pregnancy, so her immune system produces antibodies against GBS.
These antibodies can be transferred from mother to baby before birth and may therefore help protect the newborn. By making it possible to measure how many antibodies babies receive from their mothers, the new study represents an important step towards improving protection for infants, says May Murra, Postdoc at the Department of Biomedicine at Aarhus University:
"To improve our ability to protect newborns against serious GBS infections, we need to know how effectively mothers can transfer antibodies to their babies before birth. We can now gain that knowledge, having shown that the heel-prick samples already collected from newborns can be used to measure antibody levels," she explains.
The researchers compared measurements of GBS antibodies from heel-prick samples and umbilical cord blood with measurements from a standard blood sample taken from the same newborn.
The results show that measurements from heel-prick samples closely reflect the level of GBS antibodies found in standard blood samples. Umbilical cord blood also generally provided a good indication of the baby's antibody level.
"Heel-prick samples appear to be a practical and reliable way of measuring these antibodies. A major advantage is that the samples are already collected routinely, and the material is easier to collect, store and transport than standard blood samples," says May Murra.
Could contribute to the development of a vaccine for pregnant women
In the short term, the findings are particularly relevant to researchers and vaccine developers working on Group B Streptococcus vaccines for pregnant women.
The researchers have already begun investigating the relationship between the amount of GBS antibodies in a baby and the risk of developing an infection. The aim is to determine what level of antibodies is required to protect a newborn.
If it becomes possible to identify an antibody level associated with protection, this could potentially be used to assess the effectiveness of future vaccines.
"In the longer term, we hope this knowledge can help pave the way for a vaccine for pregnant women that can protect newborns against serious GBS infections. First, however, we need to learn more about what level of antibodies actually protects the baby," says May Murray.
The study is a small proof-of-concept study. This means that the researchers have primarily investigated whether the method works in principle. The research team is therefore now working to expand the study using a larger group of blood samples from different populations and countries.
More about the study:
- Type: The study is a proof-of-concept, cross-sectional study. Pregnant women were enrolled at 35–37 weeks of gestation during a routine midwife consultation at Kolding Hospital between June 2023 and January 2024.The aim was to investigate whether the concentration of IgG antibodies against GBS alpha-like surface proteins (AlpN), transferred from mother to newborn during pregnancy and measured in PKU cards and umbilical cord serum, reflects the concentration found in serum from the newborn. The study therefore investigated whether PKU cards and umbilical cord blood can be used as practical alternatives to blood samples taken directly from the newborn.
- Collaborations:The main Danish collaborators were Lillebælt Hospital/Kolding and Vejle Hospital, Aarhus University and Aarhus University Hospital, and the University of Southern Denmark. The main international collaborators were MinervaX and the Centre for Neonatal and Paediatric Infection/Vaccine Institute, University of London, United Kingdom.
- Funding: The study was partially funded by MinervaX.
- Information about possible conflicts of interest: May Murra is employed by the Department of Clinical Microbiology at Lillebælt Hospital/Vejle, which has received funding from MinervaX for research into invasive GBS disease.
