Increased detection of enterovirus 68 (EV68) among patients with acute respiratory infections has been reported from different parts of the world in the late 2000s since its first detection in pediatric patients with lower-respiratory-tract infections in 1962. However, the underlying molecular mechanisms for this trend are still unknown. We therefore aimed to study the antigenicity and receptor binding properties of EV68 detected in recent years in comparison to the prototype strain of EV68, the Fermon strain. We first performed neutralization (NT) and hemagglutination inhibition (HI) tests using antisera generated for EV68 strains detected in recent years. We found that the Fermon strain had lower HI and NT titers than recently detected EV68 strains. The HI and NT titers were also significantly different between strains of different genetic lineages among recently detected EV68 strains. We further studied receptor binding specificities of EV68 strains for sialyloligosaccharides using glycan array analysis. In glycan array analysis, all tested EV68 strains showed affinity for ␣2-6-linked sialic acids (␣2-6 SAs) compared to ␣2-3 SAs. Our study demonstrates that emergence of strains with different antigenicity is the possible reason for the increased detection of EV68 in recent years. Additionally, we found that EV68 preferably binds to ␣2-6 SAs, which suggests that EV68 might have affinity for the upper respiratory tract. IMPORTANCE Numbers of cases of enterovirus 68 (EV68) infection in different parts of the world increased significantly in the late 2000s.We studied the antigenicity and receptor binding properties of recently detected EV68 strains in comparison to the prototype strain of EV68, Fermon. The hemagglutination inhibition (HI) and neutralization (NT) titers were significantly different between strains of different genetic lineages among recently detected EV68 strains. We further studied receptor binding specificities of EV68 strains for sialyloligosaccharides using glycan array analysis, which showed affinity for ␣2-6-linked sialic acids (␣2-6 SAs) compared to ␣2-3 SAs. Our study suggested that the emergence of strains with different antigenicities was the possible reason for the increased detections of EV68 in recent years. Additionally, we revealed that EV68 preferably binds to ␣2-6 SAs. This is the first report describing the properties of EV68 receptor binding to the specific types of sialic acids.

Graphene has strong potential for electrical biosensing owing to its two-dimensional nature and high carrier mobility which transduce the direct contact of a detection target with a graphene channel to a large conductivity change in a graphene field-effect transistor (G-FET). However, the measurable range from the graphene surface is highly restricted by Debye screening, whose characteristic length is less than 1 nm at physiological ionic strength. Here, we demonstrated electrical biosensing utilizing the enzymatic products of the target. We achieved quantitative measurements of a target based on the site-binding model and real-time measurement of the enzyme kinetics in femtoliter microdroplets. The combination of a G-FET and microfluidics, named a “lab-on-a-graphene-FET”, detected the enzyme urease with high sensitivity in the zeptomole range in 100 mM sodium phosphate buffer. Also, the lab-on-a-graphene-FET detected the gastric cancer pathogen Helicobacter pylori captured at a distance greater than the Debye screening length from the G-FET.

In the present study, we describe the production of transgenic silkworms expressing a recombinant mouse mAb in their cocoons. Two transgenic lines, L‐ and H‐, were generated that carried cDNAs encoding the L‐ and H‐chains of a mouse IgG mAb, respectively, under the control of the enhancer‐linked sericin‐1 promoter. Cocoon protein analysis indicated that the IgG L‐ or H‐chain was secreted into the cocoons of each line. We also produced a transgenic line designated L/H, which carried both cDNAs, by crossing the L‐ and H‐lines. This line efficiently produced the recombinant mAb as a fully assembled H2L2 tetramer in its cocoons, with negligible L‐ or H‐chain monomer and H‐chain dimer production. Thus, the H2L2 tetramer was synthesized in, and secreted from, the middle silk gland cells. Crossing of the L/H‐line with a transgenic line expressing a baculovirus‐derived trans‐activator produced a 2.4‐fold increase in mAb expression. The recombinant mAb was extracted from the cocoons with a buffer containing 3 m urea and purified by protein G affinity column chromatography. The antigen‐binding affinity of the purified recombinant mAb was identical to that of the native mAb produced by a hybridoma. Analysis of the structure of the N‐glycans attached to the recombinant mAb revealed that the mAb contained high mannose‐, hybrid‐ and complex‐type N‐glycans. By contrast, insect‐specific paucimannose‐type glycans were not detected. Fucose residues α‐1,3‐ and α‐1,6‐linked to the core N‐acetylglucosamine residue, both of which are found in insect N‐glycans, were not observed in the N‐glycans of the mAb.

Biosynthesis of N-glycans varies significantly among tissues and is strictly regulated spatially and temporally within the tissue. The strict molecular mechanisms that are responsible for control of N-glycan synthesis remain largely unknown. We developed complementary deoxyribonucleic acid (cDNA) macroarray system and analyzed gene expression levels of more than 140 glycosyltransferases and glycosidases in the cerebral cortex from developing and adult mice. We also analyzed the relative amounts of major N-glycans present in the cerebral cortex and examined how the synthesis of N-glycans might be regulated through the expression of these genes. We demonstrated that the content of N-linked oligosaccharides dramatically changed during the course of brain development. Some of these changes could not be explained by alterations in the expression of the corresponding genes. For example, the amount of core fucosylated sugar chains in the early embryonic brain and the expression level of fucosyltransferase VIII, the only gene known to be responsible for core fucosylation, did not change proportionately. This result suggests that post-transcriptional regulation of this gene plays an important role in regulating its enzymatic activity. On the other hand, the amount of beta1,3-galactose residue-containing sugar chains increased postnatally following an increase in the level of beta1,3-galactosyltransferase messenger ribonucleic acid (mRNA). Furthermore, the amount of sugar chains with an outer fucose residue, containing LewisX-BA-2, correlated well with the expression of fusocyltransferase IX mRNA. These findings add to our understanding of the molecular mechanisms responsible for the regulation of N-glycan biosynthesis in the cerebral cortex.

Caenorhabditis elegans is an excellent model for morphogenetic research. However, little information is available on the structure of cell-surface glycans in C. elegans, although several lines of evidence have suggested a role for these glycans in cell-cell interactions during development. In this study, we analyzed N-glycan structures. Oligosaccharides liberated by hydrazinolysis from a total membrane fraction were labeled by pyridylamination, and around 90% of the N-glycans were detected as neutral oligosaccharides. The most dominant structure was Man(alpha)1-6(Man(alpha)1-3)Man(beta)1-4GlcNAc(beta)1-4GlcNAc, which is commonly found in insects. Branching structures of major oligomannose-type glycans were the same as those found in mammals. Structures that had a core fucose or non-reducing end N-acetylglucosamine were also identified, but ordinary complex-type glycans with N-acetyllactosamine were not detected as major components.

To investigate the relationship between phylogeny and glycan structures, we analyzed the structure of planarian N‐glycans. The planarian Dugesia japonica, a member of the flatworm family, is a lower metazoan. N‐glycans were prepared from whole worms by hydrazinolysis, followed by tagging with the fluorophore 2‐aminopyridine at their reducing end. The labeled N‐glycans were purified, and separated by three HPLC steps. By comparison with standard pyridylaminated N‐glycans, it was shown that the N‐glycans of planarian include high mannose‐type and pauci‐mannose‐type glycans. However, many of the major N‐glycans from planarians have novel structures, as their elution positions did not match those of the standard glycans. The results of mass spectrometry and sugar component analyses indicated that these glycans include methyl mannoses, and that the most probable linkage was 3‐O‐methylation. Furthermore, the methyl residues on the most abundant glycan may be attached to the non‐reducing‐end mannose, as the glycans were resistant to α‐mannosidase digestion. These results indicate that methylated high‐mannose‐type glycans are the most abundant structure in planarians.

Glycan Atlas is a set of glycan maps over the whole body of an organism. The glycan map that includes data of glycan structure and quantity displays micro-heterogeneity of the glycans in a tissue, an organ, or cells. The two-dimensional glycan mapping is widely used for structure analysis of N-linked oligosaccharides on glycoproteins. In this study we developed a comprehensive method for the mapping of both N- and O-glycans with and without sialic acid. The mapping data of 150 standard pyridylaminated glycans were collected. The empirical additivity rule which was proposed in former reports was able to adapt for this extended glycan map. The adapted rule is that the elution time of pyridylamino glycans on high performance liquid chromatography (HPLC) is expected to be the simple sum of the partial elution times assigned to each monosaccharide residue. The comprehensive mapping method developed in this study is a powerful tool for describing the micro-heterogeneity of the glycans. Furthermore, we prepared 42 pyridylamino (PA-) glycans from human serum and were able to draw the map of human serum N- and O-glycans as an initial step of Glycan Atlas editing.

There are global concerns about threat of pandemic caused by the human-infectious avian influenza virus. To prevent the oncoming pandemic, it is crucial to analyze the viral affinity to human-type or avian-type sialoglycans with high sensitivity at high speed. Graphene-FET (G-FET) realizes such high-sensitive electrical detection of the targets, owing to graphene’s high carrier mobility. In the present study, G-FET was functionalized using sialoglycans and employed for the selective detection of lectins from Sambucus sieboldiana and Maackia amurensis as alternatives of the human and avian influenza viruses. Glycan-functionalized G-FET selectively monitored the sialoglycan-specific binding reactions at subnanomolar sensitivity.