HIV-1 Is Associated With Lower Group B Streptococcus Capsular and Surface-Protein IgG Antibody Levels and Reduced Transplacental Antibody Transfer in Pregnant Women

Abstract

Background: Human immunodeficiency virus (HIV)-exposed infants are at increased risk of invasive Group B Streptococcus (GBS) disease; however, the reason for this increased susceptibility has not been characterized.

Methods: We compared GBS capsular and surface-protein maternal immunoglobin G antibody concentrations and cord-maternal ratios between HIV-infected and HIV-uninfected mother-newborn dyads.

Results: Median capsular antibody concentrations (µg/mL) were lower in HIV-infected than HIV-uninfected women for serotypes Ib (P = .033) and V (P = .040); and for pilus island (PI)-1 (P = .016), PI-2a (P = .015), PI-2b (P = .015), and fibrinogen-binding protein A (P < .001). For serotypes Ia and III, cord-maternal ratios were 37.4% (P < .001) and 32.5% (P = .027) lower in HIV-infected compared to HIV-uninfected mother-newborn dyads. The adjusted odds of having capsular antibody concentration ≥2 µg/mL when comparing HIV-infected to -uninfected women were 0.33 (95% confidence interval [CI], .15-.75) and 0.34 (95% CI, .12-1.00) for serotypes Ia and III, respectively. Antibody levels and cord-maternal ratios were independent of CD4(+) lymphocyte counts or HIV-1 viral load.

Conclusions: The lower GBS antibody concentrations and reduced transplacental antibody transfer in HIV-infected women, which likely contribute to their infants being at heightened susceptibility for invasive GBS disease, could possibly be mitigated by vaccination with a GBS conjugate vaccine currently under clinical development.

Keywords: Group B Streptococcus; HIV; Streptococcus agalactiae; antibody; immunity; transplacental transfer.