Standardizing GBS capsular antibody concentration and functional assays to expedite GBS vaccine licensure
A vaccine given to pregnant women is highly desirable to prevent GBS disease and would provide protection for mothers and infants. However, field trials enrolling thousands of pregnant women and infants would be needed to assess how effective the vaccine was in preventing GBS disease in babies. These trials would be very challenging to implement in developing countries. Furthermore, global implementation of intrapartum antibiotic prophylaxis will make it more difficult to conduct such studies and leave those in developing countries, where the infrastructure required for implementation is absent, at sustained risk. An alternative approach that has been used for vaccines against meningitis in the past is to identify a marker (for example amount of antibody) that tells us if a person is protected against the disease. For GBS, studies have shown that women with higher antibody in their blood are less likely to have babies how go on to have GBS disease.
However, to be sure that we have confidence in such a test, we need to develop the test in a way that it can be carried out in the same way everywhere (assay standardisation).
There is no current standard test on antibody but o ver the last 40 years, 34 different quantitative and 12 different functional assays have been described, Consensus is growing that standardization of GBS assays would represent a major milestone towards developing a vaccine against GBS.
We aim to develop a standard approach to measuring the amount and functional ability of antibody to kill GBS in a laboratory test that can be conducted to the same standard in different settings.
Our consortium of partners from academic institutions, public health bodies, industry and regulatory representatives are working together to develop assays that will tell us not only how much antibody we need but how this relates to how well the antibody kills the GBS in the laboratory test. We will develop standard reagents to use in these assays that will be freely available to everyone working with GBS and publish a recipe of how to use these in assays.
The assays are due for completion in 2019.
Contact us to find out more information.
This study is funded by Bill and Melinda Gates Foundation.