Seroprevalence of Opsonophagocytic Antibodies against Serotype Ia, Ib, II, III, and V Group B Streptococcus among Korean Population

Abstract

BackgroundInvasive Streptococcus agalactiae (group B streptococcus, GBS) infection most commonly occurs in infants; however, cases of GBS infection in adults, particularly in the elderly with significant underlying diseases, are being increasingly reported. We analyzed the serotype specific opsonophagocytic antibodies (the major mechanism of protection against GBS) in infants, adults, and the elderly.MethodsThe opsonization indices (OIs) of antibodies against serotype Ia, Ib, II, III, and V GBS were studied in 89 infants, 35 adults (age, 30–50 years), and 62 elderly individuals (age, 65–85 years) according to the University of Alabama at Birmingham GBS opsonophagocytic killing assay protocol (www.vaccine.uab.edu).ResultsIn infants, adults, and elderly groups respectively, geometric mean of OI against GBS serotype Ia were 3, 7, and 32; against GBS serotype Ib were 7, 242, and 252; against serotype II were 93, 363, and 676; against serotype III were 8, 212, and 609; and against serotype V were 4, 639, and 610. The seropositive rate (% of subjects with OI ≥ 4) increased significantly in older age group for all five serotypes.ConclusionDuring infancy, only a limited proportion of infants have functional immunity against serotype Ia, Ib, II, III, and V GBS. Furthermore, a lack of opsonic activities against GBS observed in some adults and the elderly might predispose such individuals to the risk of invasive GBS infection. Epidemiological monitoring and development of suitable vaccine for these populations are needed.

Using Surface Immunogenic Protein as a Carrier Protein to Elicit Protective Antibody to Multiple Serotypes for Candidate Group B Streptococcal Glycan Conjugate Vaccines

“…The opsonophagocytic assay was conducted following established protocols in the literature [ 50 , 51 , 52 ]. Specifically, HL60 cells were cultured and passaged in Iscove’s Modified Dulbecco Medium (IMDM) (Pricella, Wuhan, China) supplemented with 20% Fetal Bovine Serum (FBS) (Gibco, New York, NY, USA) and 1% penicillin-streptomycin at 37 °C under a 5% CO 2 atmosphere.…”

Development of A Standardized Opsonophagocytosis Killing Assay for Group B Streptococcus and Assessment in an Interlaboratory Study

“…Older studies determined the degree of bacterial killing over a fixed incubation period caused by a human serum sample with an endogenous complement [12]. More recent studies assessing pneumococcal vaccines have determined the dilution of antiserum that kills at least 50% of the target bacteria in the presence of an exogenous complement, either with a viable count or fluorescence endpoint [13][14][15].…”

Importance of Functional Assessment of Immunity against Group B Streptococcus

“…In the current issue of Journal of Korean Medical Science , Lee et al4 reported the seroprevalence of opsonophagocytic antibodies against GBS serotype Ia, Ib, II, III, and V among different age groups. The five serotypes included in the analysis account for up to 94.1%–99.0% of all invasive GBS infections among young infants 56.…”