The Protective Value of Maternal Group B Streptococcus Antibodies: Quantitative and Functional Analysis of Naturally Acquired Responses to Capsular Polysaccharides and Pilus Proteins in European Maternal Sera
PubMed | GSK Vaccines Srl and Instituto Superiore Of Sanita
Type: Journal Article | Journal: Clinical infectious diseases : an official publication of the Infectious Diseases Society of America | Year: 2016
Group B Streptococcus (GBS) is a major cause of neonatal sepsis and meningitis. A vaccine targeting pregnant women could protect infants through placentally transferred antibodies. The association between GBS maternal antibody concentrations and the risk of neonatal infection has been investigated in US and African populations. Here we studied naturally acquired immunoglobulin G (IgG) responses to GBS capsular polysaccharides (CPS) and pilus proteins in European pregnant women.Maternal sera were prospectively collected in 8 EU countries from 473 GBS non-colonized and 984 colonized pregnant women who delivered healthy neonates and from 153 mothers of infants with GBS disease. GBS strains from these colonized women and infected infants were obtained in parallel and their capsular and pilus types were identified by serological and molecular methods. Maternal serum concentrations of IgG anti- Ia, -Ib, -III and -V polysaccharides and anti-BP-1, -AP1-2a and -BP-2b pilus proteins were determined by enzyme-linked immunosorbent assay. Antibody functional activity was quantified by Opsonophagocytic Killing Assay.Antibody levels against CPS and pilus proteins were significantly higher in GBS colonized women delivering healthy babies than in mothers of neonates with GBS disease or non-colonized women. Moreover, maternal anti-capsular IgG concentrations showed a significant correlation with functional titers measured by Opsonophagocytic Killing Assay.Maternal anti-capsular IgG concentrations above 1 g/mL mediated GBS killing in vitro and were predicted to respectively reduce by 81% (95% confidence interval, 40%-100%) and 78% (45%-100%) the risk of GBS Ia and III early-onset disease in Europe.
PubMed | GSK Vaccines Srl.
Type: Journal Article | Journal: Journal of preventive medicine and hygiene | Year: 2016
A century of traditional vaccinology lost the fight against meningococcus serogroup B (MenB). However, thanks to an innovative genome-based approach, the first broadly effective MenB vaccine, Bexsero (GSK Vaccines), was developed and has been licensed for use in various age groups by the European Commission and other regulatory authorities. Genes encoding for the main meningococcus B antigens were identified and screened in order to achieve a broadly protective vaccine, taking into account the fact that meningococcus B has many different subtypes whose membrane proteins may be different. Since the antigens selected for Bexsero are also harbored by meningococci belonging to other serogroups there may be the potential for Bexsero to offer a certain level of protection against non-B serogroups. Therefore preliminary studies were carried out to investigate the potential of the vaccine to also provide a degree of cross protection against non-B serogroups. Here we review the potential for Bexsero to offer a certain level of protection against the diversity of meningococcus type B subtypes and its potential ability to offer some cross protection from non-B serogroups. Lastly, we describe the future perspectives in pentavalent meningococcal vaccine (ABCWY) development which hopefully will result in a vaccine able to help prevent Invasive Meningococcal Diseases (IMD) from the majority of currently circulating meningococcal strains.