title: Recombinant group B Streptococcus alpha-like protein 3 is an effective immunogen and carrier protein.
abstract: Conjugate vaccines against pathogens of multiple serotypes are optimized when all components induce functional antibody, resulting in broadened coverage. While most clinical studies of vaccines against group B Streptococcus (GBS) have evaluated conjugates composed of capsular polysaccharide (CPS) coupled to tetanus toxoid, conjugates prepared with GBS proteins as carriers have also been efficacious in animals. Here, we report that recombinant GBS alpha-like protein 3 (rAlp3) is both a strong immunogen and a viable carrier protein for type III CPS. The type III CPS-specific immunoglobulin G (IgG) titer rose from <100 to 64,000 among mice that received type III CPS coupled to rAlp3 (III-rAlp3) compared with an absence of a specific response among mice that received an uncoupled mixture. Most (94%) newborn pups born to III-rAlp-vaccinated dams survived challenge with viable type III GBS, compared with 43% survival among those born to dams that received the uncoupled mixture (P < 0.0001). A tricomponent conjugate of type III CPS, rAlp3, and a GBS recombinant beta C protein lacking its IgA binding site (III-rAlp3-rBCP(DeltaIgA)) provided protection against a serotype III strain and a serotype Ia strain bearing beta C protein. High-titered anti-rAlp3 rabbit serum opsonized Alp3-containing strains of two GBS serotypes (types V and VIII) and invasive type III strains bearing the cross-reactive Rib protein for in vitro killing by human peripheral blood leukocytes. Thus, the potential exists for the inclusion of rAlp3 in a GBS vaccine formulated to provide multiserotype coverage.
authors.affiliation: Department of Medicine, Channing Laboratory, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts 02115, USA.
authors.forename: Hsiao-Hui
authors.initials: HH
authors.lastname: Yang
authors.forename: Samantha J
authors.initials: SJ
authors.lastname: Mascuch
authors.forename: Lawrence C
authors.initials: LC
authors.lastname: Madoff
authors.forename: Lawrence C
authors.initials: LC
authors.lastname: Paoletti
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D000907:Antibodies, Bacterial / Q000096:biosynthesis / Q000276:immunology; D000942:Antigens, Bacterial / Q000276:immunology*; D016667:Bacterial Capsules / Q000276:immunology* / Q000378:metabolism; D001426:Bacterial Proteins / Q000276:immunology*; D005260:Female; D051379:Mice; D010587:Phagocytosis; D011994:Recombinant Proteins / Q000276:immunology / Q000378:metabolism; D013290:Streptococcal Infections / Q000276:immunology* / Q000517:prevention & control; D022541:Streptococcal Vaccines / Q000276:immunology*; D013292:Streptococcus agalactiae / Q000276:immunology*; D018074:Vaccines, Conjugate / Q000276:immunology
chemical_list: D000907:Antibodies, Bacterial; D000942:Antigens, Bacterial; D001426:Bacterial Proteins; D011994:Recombinant Proteins; D022541:Streptococcal Vaccines; D018074:Vaccines, Conjugate; C500211:alpha-like protein 3, Streptococcus agalactiae