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Background Group B streptococcus (GBS) causes serious diseases in newborn infants, often resulting in lifelong neurologic impairments or death. Prophylactic vaccination of pregnant women prior to delivery could provide comprehensive protection, as early onset and late-onset disease and maternal complications potentially could be addressed. Methods Capsular polysaccharide conjugate vaccine GBS6 was designed using surveillance data yielded by whole-genome sequencing of a global collection of recently recovered GBS isolates responsible for invasive neonatal GBS disease. Capsular polysaccharides were isolated, oxidized using sodium periodate, and conjugated to CRM197 by reductive amination in dimethyl sulfoxide. Immune responses in mice and rhesus macaques were measured in a multiplex Luminex immunoglobulin G (IgG) assay and opsonophagocytic activity assays. Results The optimized conjugates were immunogenic, alone and in combination, in mice and rhesus macaques, inducing IgG antibodies that mediated opsonophagocytic killing. Active immunization of murine dams with GBS6 prior to mating resulted in serotype-specific protection of pups from a lethal challenge with GBS. Protection following passive administration of serotype-specific IgG monoclonal antibodies to dams demonstrated conclusively that anticapsular polysaccharide IgG alone is sufficient for protection. Conclusions The findings support the ongoing clinical evaluation of maternal GBS6 vaccination as a potential alternative method to prevent GBS disease in infants., Six-valent capsular polysaccharide conjugate vaccine GBS6 for the prevention of neonatal Group B Streptococcal (GBS) infections was evaluated in preclinical models. Vaccination with GBS6 or administration of serotype-specific IgG to pregnant dams protected pups against lethal challenges with GBS.

A recombinant Clostridium difficile expression system was used to produce genetically engineered toxoids A and B as immunogens for a prophylactic vaccine against C. difficile– associated disease. Although all known enzymatic activities responsible for cytotoxicity were genetically abrogated, the toxoids exhibited residual cytotoxic activity as measured in an in vitro cell-based cytotoxicity assay. The residual cytotoxicity was eliminated by treating the toxoids with 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) and N-hydroxysuccinimide. Mass spectrometry and amino acid analysis of the EDC-inactivated toxoids identified crosslinks, glycine adducts, and β-alanine adducts. Surface plasmon resonance analysis demonstrated that modifications resulting from the chemical treatment did not appreciably affect recognition of epitopes by both toxin A- and B-specific neutralizing monoclonal antibodies. Compared to formaldehyde-inactivated toxoids, the EDC/N-hydroxysuccinimide–inactivated toxoids exhibited superior stability in solution with respect to reversion of cytotoxic activity.

α-Mannosidase catalyzes the removal of the O -linked mannose units from mannopeptimycin-α. The reaction can be run on a preparative scale to allow isolation of mannopeptimycin-β or the mono- O -mannosyl intermediate according to the choice of catalyst.

Biogenesis of the pipecolate moiety of neuroprotective agent meridamycin in Streptomyces sp. NRRL30748 was investigated in feeding studies using lysine specifically labeled with (15)N at the α-amino or the e-amino nitrogen position. Fourier transform mass spectrometry analysis with ultra-high mass resolving power and accurate mass measurement capability was employed to resolve the (15)N peak of labeled meridamycin from the (13)C peak of unlabeled meridamycin, allowing the precise calculation of labeling contents under each condition. The relative enrichment of (15)N-labeled meridamycin was ~43% with L-[α-(15)N]-lysine feeding and ~14% with L-[α-(15)N]-lysine feeding, suggesting two distinguishable pathways, with concomitant loss of either the e-amino group or the α-amino group of lysine, were involved in the generation of the pipecolate moiety of meridamycin in this bacterium. PCR cloning using degenerate primers identified a proC gene encoding a putative pyrroline-5-carboxylate reductase, which was expected to catalyze the conversion of piperideine-6-carboxylate to pipecolate. However, inactivation of this locus did not significantly affect the incorporation of α-(15)N- or e-(15)N-labeled lysine into meridamycin, indicating the existence of an alternative route for the last step of the lysine e-transamination pathway. This work revealed the diversity and complexity of the biosynthetic pathways for pipecolate synthesis in the meridamycin producing bacterium Streptomyces sp. NRRL30748.