Despite substantial progress in prevention of perinatal group B streptococcal (GBS) disease since the 1990s, GBS remains the leading cause of early-onset neonatal sepsis in the United States In 1996, CDC, in collaboration with relevant professional societies, published guidelines for the prevention of perinatal group B streptococcal disease (CDC Prevention of perinatal group B streptococcal disease: a public health perspective MMWR 1996;45[No RR-7]); those guidelines were updated and republished in 2002 (CDC Prevention of perinatal group B streptococcal disease: revised guidelines from CDC MMWR 2002;51[No RR-11]) In June 2009, a meeting of clinical and public health representatives was held to reevaluate prevention strategies on the basis of data collected after the issuance of the 2002 guidelines This report presents CDC's updated guidelines, which have been endorsed by the American College of Obstetricians and Gynecologists, the American Academy of Pediatrics, the American College of Nurse-Midwives, the American Academy of Family Physicians, and the American Society for Microbiology The recommendations were made on the basis of available evidence when such evidence was sufficient and on expert opinion when available evidence was insufficient The key changes in the 2010 guidelines include the following: • expanded recommendations on laboratory methods for the identification of GBS, • clarification of the colony-count threshold required for reporting GBS detected in the urine of pregnant women, • updated algorithms for GBS screening and intrapartum chemoprophylaxis for women with preterm labor or preterm premature rupture of membranes, • a change in the recommended dose of penicillin-G for chemoprophylaxis, • updated prophylaxis regimens for women with penicillin allergy, and • a revised algorithm for management of newborns with respect to risk for early-onset GBS disease Universal screening at 35-37 weeks' gestation for maternal GBS colonization and use of intrapartum antibiotic prophylaxis has resulted in substantial reductions in the burden of early-onset GBS disease among newborns Although early-onset GBS disease has become relatively uncommon in recent years, the rates of maternal GBS colonization (and therefore the risk for early-onset GBS disease in the absence of intrapartum antibiotic prophylaxis) remain unchanged since the 1970s Continued efforts are needed to sustain and improve on the progress achieved in the prevention of GBS disease There also is a need to monitor for potential adverse consequences of intrapartum antibiotic prophylaxis (eg, emergence of bacterial antimicrobial resistance or increased incidence or severity of non-GBS neonatal pathogens) In the absence of a licensed GBS vaccine, universal screening and intrapartum antibiotic prophylaxis continue to be the cornerstones of early-onset GBS disease prevention

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Prevention of perinatal group B streptococcal disease. Revised guidelines from CDC.

https://www.cell.com/cell/pdf/S0092-8674(05)00451-4.pdf

An immunomodulatory molecule of symbiotic bacteria directs maturation of the host immune system.

Antibodies targeting CTLA-4 have been successfully used as cancer immunotherapy. We find that the antitumor effects of CTLA-4 blockade depend on distinct Bacteroides species. In mice and patients, T cell responses specific for B. thetaiotaomicron or B. fragilis were associated with the efficacy of CTLA-4 blockade. Tumors in antibiotic-treated or germ-free mice did not respond to CTLA blockade. This defect was overcome by gavage with B. fragilis, by immunization with B. fragilis polysaccharides, or by adoptive transfer of B. fragilis–specific T cells. Fecal microbial transplantation from humans to mice confirmed that treatment of melanoma patients with antibodies against CTLA-4 favored the outgrowth of B. fragilis with anticancer properties. This study reveals a key role for Bacteroidales in the immunostimulatory effects of CTLA-4 blockade.

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Anticancer immunotherapy by CTLA-4 blockade relies on the gut microbiota

The enzymic degradation of insoluble polysaccharides is one of the most important reactions on earth. Despite this, glycoside hydrolases attack such polysaccharides relatively inefficiently as their target glycosidic bonds are often inaccessible to the active site of the appropriate enzymes. In order to overcome these problems, many of the glycoside hydrolases that utilize insoluble substrates are modular, comprising catalytic modules appended to one or more non-catalytic CBMs (carbohydrate-binding modules). CBMs promote the association of the enzyme with the substrate. In view of the central role that CBMs play in the enzymic hydrolysis of plant structural and storage polysaccharides, the ligand specificity displayed by these protein modules and the mechanism by which they recognize their target carbohydrates have received considerable attention since their discovery almost 20 years ago. In the last few years, CBM research has harnessed structural, functional and bioinformatic approaches to elucidate the molecular determinants that drive CBM–carbohydrate recognition. The present review summarizes the impact structural biology has had on our understanding of the mechanisms by which CBMs bind to their target ligands.

Carbohydrate-binding modules: fine-tuning polysaccharide recognition

Since the discovery of organic azides by Peter Griess more than 140 years ago, numerous syntheses of these energy-rich molecules have been developed. In more recent times in particular, completely new perspectives have been developed for their use in peptide chemistry, combinatorial chemistry, and heterocyclic synthesis. Organic azides have assumed an important position at the interface between chemistry, biology, medicine, and materials science. In this Review, the fundamental characteristics of azide chemistry and current developments are presented. The focus will be placed on cycloadditions (Huisgen reaction), aza ylide chemistry, and the synthesis of heterocycles. Further reactions such as the aza-Wittig reaction, the Sundberg rearrangement, the Staudinger ligation, the Boyer and Boyer-Aube rearrangements, the Curtius rearrangement, the Schmidt rearrangement, and the Hemetsberger rearrangement bear witness to the versatility of modern azide chemistry.

Organic Azides: An Exploding Diversity of a Unique Class of Compounds

http://www.jbc.org/content/250/5/1926.full.pdf

Structural determination of the sialic acid polysaccharide antigens of Neisseria meningitidis serogroups B and C with carbon 13 nuclear magnetic resonance.

Group B Streptococcus (GBS) is an important perinatal pathogen. Because transplacentally acquired maternal antibodies to the GBS capsular polysaccharides (CPS) confer protection, prevention of infant disease may be possible after immunization of women. Unfortunately, the purified CPS of GBS are only variably immunogenic in adults; therefore to enhance immunogenicity we have designed and developed a CPS-protein conjugate vaccine. The lability of a conformationally dependent epitope on the III CPS containing a critical sialic acid residue was important to consider in vaccine design. 100 women were randomized to receive GBS type III CPS-tetanus toxoid conjugate (III-TT) vaccine at one of three doses; unconjugated GBS type III CPS; or saline. Serum samples were obtained before immunization and 2, 4, 8, and 26 wk thereafter, and specific antibody to type III CPS was measured. Vaccines were well tolerated. In sera from recipients of the highest dose of III-TT, CPS-specific IgG levels rose from a geometric mean of 0.09 microg/ml before immunization to 4.53 microg/ml 8 wk later, whereas levels in recipients of unconjugated type III CPS rose from 0.21 microg/ml to 1.41 microg/ml. Lower doses resulted in lower antibody levels. A > or = 4-fold rise in antibody concentration was achieved in 90% of recipients of III-TT compared with 50% of those that received III CPS (P = 0.0015). Antibodies evoked by the conjugate vaccine recognized a conformationally dependent epitope of the III-CPS, promoted opsonophagocytosis and killing of GBS, and, after maternal immunization, protected neonatal mice from lethal challenge with type III GBS. We conclude that directed coupling of type III GBS polysaccharide to a carrier protein yielded a conjugate vaccine with preserved expression of a highly labile conformational epitope involving sialic acid and enhanced immunogenicity compared with uncoupled CPS.

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Immune response to type III group B streptococcal polysaccharide-tetanus toxoid conjugate vaccine.

Composition, sequence, and conformation of polymers and oligomers of glucose as revealed by carbon-13 nuclear magentic resonance.

The native capsular polysaccharide of type III group B Streptococcus elicits a specific antibody response in only 60% of nonimmune human subjects. To enhance the immunogenicity of this polysaccharide, we coupled the type III polysaccharide to tetanus toxoid. Prior to coupling, aldehyde groups were introduced on the polysaccharide by controlled periodate oxidation, resulting in the conversion of 25% of the sialic acid residues of the polysaccharide to residues of the 8-carbon analogue of sialic acid, 5-acetamido-3,5-dideoxy-D-galactosyloctulosonic acid. Tetanus toxoid was conjugated to the polysaccharide by reductive amination, via the free aldehyde groups present on the partially oxidized sialic acid residues. Rabbits vaccinated with the conjugate vaccine produced IgG antibodies that reacted with the native type III group B streptococcal polysaccharide (3/3 rabbits), while rabbits immunized with the unconjugated type III polysaccharide failed to respond (0/3 rabbits). Sera from animals receiving conjugate vaccine opsonized type III group B streptococci for phagocytic killing by human peripheral blood leukocytes, and protected mice against lethal challenge with live type III group B streptococci. The results suggest that this method of conjugation to a carrier protein may be a useful strategy to improve the immunogenicity of the type III group B Streptococcus polysaccharide in human subjects.

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Harold J. Jennings

Papers

Structural determination of the sialic acid polysaccharide antigens of Neisseria meningitidis serogroups B and C with carbon 13 nuclear magnetic resonance.

Immune response to type III group B streptococcal polysaccharide-tetanus toxoid conjugate vaccine.

Composition, sequence, and conformation of polymers and oligomers of glucose as revealed by carbon-13 nuclear magentic resonance.

Immunogenicity in animals of a polysaccharide-protein conjugate vaccine against type III group B Streptococcus.

Capsular sialic acid prevents activation of the alternative complement pathway by type III, group B streptococci.