Association between maternal Group B Streptococcus surface-protein antibody concentrations and invasive disease in their infants

Abstract

Objectives: Group B Streptococcus (GBS) surface-proteins have been shown to be immunogenic and potential vaccine candidates. We aim to determine the association between maternal IgG antibodies to select GBS surface-proteins and invasive GBS disease in their infants. Methods: Using a matched case–control study, maternal antibody levels for GBS-immunogenic bacterial adhesin, fibrinogen-binding protein A and pilus-island (PI) PI-1, PI-2a, PI-2b were compared between infants with invasive GBS disease and well-baby controls. Results: The absolute risk of disease did not differ between cases and colonized controls with increasing antibody concentrations for these surface-proteins. There was, however, a relative risk reduction in invasive disease associated with fibrinogen-binding protein A, with an adjusted odds ratio of 0.04 (95% CI: 0.01–0.69) at antibody levels ≥10,000 AU/ml. Conclusion: We have not demonstrated an association between naturally occurring fibrinogen-binding protein A, GBS-immunogenic bacterial adhesin, and PI surface-protein antibodies and the risk of invasive disease in young infants. These surface-proteins may not be suitable GBS vaccine candidates.

Keywords:

• BibA
• FbsA
• GBS
• Group B Streptococcus
• pilus island
• Streptococcus agalactiae

Financial & competing interests disclosure

Z Dangor is funded in part by the Carnegie Corp of New York (Grant number B8749) and the Discovery Foundation (Grant number 20289/1). SG Lala is funded in part by a career development award from the Medical Research Council of South Africa. SA Madhi is funded in part by National Research Foundation/Department of Science and Technology: South African Research Chair Initiative in Vaccine Preventable Diseases and Medical Research Council of South Africa. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. The authors have no other relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript apart from those disclosed.

Key issues

• Group B Streptococcus (GBS) is a common cause of sepsis and meningitis in young infants.

• An alternative strategy to GBS prevention is maternal vaccination, to which a trivalent capsular polysaccharide conjugate vaccine has completed Phase II trials.

• This vaccine, although covers the most prevalent GBS serotypes globally, may be less effective in certain regions and the risk for replacement disease is a possibility.

• Immunogenic GBS surface-proteins have been identified and favor survival in mice challenge studies.

• This is the first study conducted in infants with invasive disease, in which no association was demonstrated for antibodies to fibrinogen-binding protein A, GBS-immunogenic bacterial adhesin, and pilus island proteins.

• These surface-proteins are unlikely to be suitable vaccine candidates.

Notes