Analyzing the Substrate Specificity of a Class of Long-Horned-Beetle-Derived Xylanases by Using Synthetic Arabinoxylan Oligo- and Polysaccharides.

Xylophagous long-horned beetles thrive in challenging environments. To access nutrients, they secrete plant-cell-wall-degrading enzymes in their gut fluid; among them are cellulases of the subfamily 2 of glycoside hydrolase family 5 (GH5_2). Recently, we discovered that several beetle-derived GH5_2s use xylan as a substrate instead of cellulose, which is unusual for this family of enzymes. Here, we analyze the substrate specificity of a GH5_2 xylanase from the beetle Apriona japonica (AJAGH5_2-1) using commercially available substrates and synthetic arabinoxylan oligo- and polysaccharides. We demonstrate that AJAGH5_2-1 processes arabinoxylan polysaccharides in a manner distinct from classical xylanase families such as GH10 and GH11. AJAGH5_2-1 is active on long oligosaccharides and cleaves at the non-reducing end of a substituted xylose residue (position +1) only if: 1) three xylose residues are present upstream and downstream of the cleavage site, and 2) xylose residues at positions -1, -2, +2 and +3 are not substituted.

Conformational Studies of Oligosaccharides.

The conformation of a molecule strongly affects its function, as demonstrated for peptides and nucleic acids. This correlation is much less established for carbohydrates, the most abundant organic materials in nature. Recent advances in synthetic and analytical techniques have enabled the study of carbohydrates at the molecular level. Recurrent structural features were identified as responsible for particular biological activities or material properties. In this Minireview, recent achievements in the structural characterization of carbohydrates, enabled by systematic studies of chemically defined oligosaccharides, are discussed. These findings can guide the development of more potent glycomimetics. Synthetic carbohydrate materials by design can be envisioned.

Gold nanoparticles morphology does not affect the multivalent presentation and antibody recognition of Group A Streptococcus synthetic oligorhamnans.

The development of novel delivery systems capable of enhancing the antibody binding affinity and immunoactivity of short length saccharide antigens is at the forefront of modern medicine. In this regard, gold nanoparticles (AuNPs) raised great interest as promising nano-vaccine platform, as they do not interfere with the desired immune response and their surface can be easily functionalized, enabling the antigen multivalent presentation. In addition, the nanoparticles morphology can have a great impact on their biological properties. Gram-positive Group A Streptococcus (GAS) is a bacterium responsible for many infections and represents a priority healthcare concern, but a universal vaccine is still unavailable. Since all the GAS strains have a cell wall characterized by a common polyrhamnose backbone, this can be employed as alternative antigen to develop an anti-GAS vaccine. Herein, we present the synthesis of two oligorhamnoside fragments and their corresponding oligorhamnoside-AuNPs, designed with two different morphologies. By competitive ELISA we assessed that both symmetric and anisotropic oligorhamnan nanoparticles inhibit the binding of specific polyclonal serum much better than the unconjugated oligosaccharides.

Functional analysis of endoplasmic reticulum glucosyltransferase (UGGT): Synthetic chemistry's initiative in glycobiology.

UGGT1 is called as a folding sensor protein that recognizes misfolded glycoproteins and selectively glucosylates high-mannose-type glycans on the proteins. However, conventional approaches using naturally occurring glycoproteins is not optimum in performing precise analysis of the unique properties of UGGT1. We have demonstrated that high-mannose-type glycans, in which various hydrophobic aglycons were introduced, act as good substrates for UGGT1 and are useful analytical tools for its characterization. Moreover, we found that UGGT2, an isoform UGGT1, is also capable of glucosylating these synthetic substrates. Our strategy stemmed on synthetic chemistry has been further strengthened by total synthesis of homogeneous glycoproteins in correctly folded as well as in intentionally misfolded forms.

Glycoconjugate vaccines: current approaches towards faster vaccine design.

Introduction: Over the last decades, glycoconjugate vaccines have been proven to be a successful strategy to prevent infectious diseases. Many diseases remain to be controlled, especially in developing countries, and emerging antibiotic-resistant bacteria present an alarming public-health threat. The increasing complexity of future vaccines, and the need to accelerate development processes have triggered the development of faster approaches to glycoconjugate vaccines design. Areas covered: This review provides an overview of recent progress in glycoconjugation technologies toward faster vaccine design. Expert opinion: Among the different emerging approaches, glycoengineering has the potential to combine glycan assembly and conjugation to carrier systems (such as proteins or outer membrane vesicles) in one step, resulting in a simplified manufacturing process and fewer analytical controls. Chemical and enzymatic strategies, and their automation can facilitate glycoepitope identification for vaccine design. Other approaches, such as the liposomal encapsulation of polysaccharides, potentially enable fast and easy combination of numerous antigens in the same formulation. Additional progress is envisaged in the near future, and some of these systems still need to be further validated in humans. In parallel, new strategies are needed to accelerate the vaccine development process, including the associated clinical trials, up to vaccine release onto the market.

Estrategia regulatoria del desarrollo de Quimi-Hib®, vacuna conjugada semisintética contra Haemophilus influenzae tipo b

Introducción: Quimi-Hib®, una vacuna cubana obtenida por síntesis química y única en el mundo, requirió una estrategia regulatoria específica, porque no hay guía con las pautas requeridas para su producción y control. Objetivo: Caracterizar la estrategia regulatoria de la etapa precomercialización de Quimi-Hib® en Cuba. Material y Métodos: Estudio descriptivo-retrospectivo de requisitos para el registro sanitario de la vacuna cubana. Se establecieron siete pasos estratégicos para abarcar los estándares reguladores vigentes y futuros, con base en opiniones de expertos para la adopción de decisiones. El punto de partida fue la guía de la OMS, aplicable a vacunas anti-Hib de origen natural. Resultados: La estrategia regulatoria se desarrolló a partir de las 15 recomendaciones de esta guía, 11 de ellas se extrapolaron a la vacuna cubana y cuatro no, pero se consideraron sus fundamentos para desarrollar cuatro requerimientos aplicables a la vacuna semisintética. Se adicionaron otros seis, tres a solicitud de la Autoridad Reguladora Nacional de Cuba y tres obtenidos de la literatura relevante disponible. Estos 21 requerimientos completan el paquete regulador, resultado de la estrategia desarrollada para esta vacuna y la posterior aprobación de su registro sanitario y comercialización. Conclusiones: La estrategia regulatoria desarrollada en este trabajo permitió definir un conjunto de recomendaciones que suple la carencia de regulaciones internacionales y contribuyó a la obtención segura del registro sanitario de la vacuna Quim-Hib® que podría generalizarse a otras vacunas con características similares.

Introduction: Quimi-Hib®, a Cuban vaccine obtained by chemical synthesis and unique in the world, required its own regulatory strategy because there is no guideline on the requirements for its production and control. Objective: To characterize the regulatory strategy of the pre-launch phase of Quimi-Hib® in Cuba. Material and Methods: Descriptive-retrospective study of the requirements for the approval of the Cuban vaccine. Seven strategic steps were established to cover current and future regulatory standards based on expert advice for decision making. The starting point was the WHO´s guideline, which applies to anti-Hib vaccines of natural origin. Results: The regulatory strategy was developed based on the 15 recommendations of the aforementioned guideline, 11 of which were extrapolated to the Cuban vaccine and four of which were not, but served as the basis for the development of four requirements with similar rationale that apply to the semisynthetic vaccine. Six additional requirements were added, three of which were requested from the Cuba's National Regulatory Authority and three of which were obtained from the available relevant literature. These 21 requirements complete the regulatory package, the result of the strategy developed for this vaccine and the subsequent approval for marketing authorization and commercialization. Conclusions: The regulatory strategy compensates for the lack of specific guidelines for synthetic Haemophilus influenzae type b vaccines and thus contributed to the approval of the first vaccine of this type. The regulatory strategy is flexible because it includes update requirements throughout the vaccine life cycle, and expert consensus was considered in its development.