Standardising assays for the assessment of serocorrelates of protection of antibodies against key GBS proteins to facilitate vaccine licensure

Summary

Group B Streptococcus (GBS) is a leading cause of neonatal infections and causes stillbirths and preterm births.  GBS can also cause infections in the elderly and immunocompromised host. Vaccine development is currently undergoing clinical trials and there are two vaccine candidates, one developed to make antibodies against the GBS coat (the capsule) and one against key proteins on the GBS surface. The capsule changes with each of the 10 types of GBS, but key proteins are the same for all types of GBS. Although GBS is a leading cause of disease, it is still relatively rare and testing a vaccine in such a rare disease would be too complex and too costly. It is now widely agreed that giving a vaccine against to pregnant women is a priority and that the vaccine could be licenced based on measuring the amount of antibodies needed to protect against infection using standardised laboratory tests followed by a large clinical trial after the vaccine is licenced to look at vaccine effectiveness. Such an approach has been used for vaccines like the meningitis B vaccine given to children under the age of 1 year. However, to develop this laboratory test we need to develop standard reagents that every laboratory wishing to test antibodies can use. We are already developing reagents to study antibodies against the capsule and this proposal aims to now develop reagents against key proteins so that we can finally get GBS vaccines to those who need them most.