CaSR modulates proliferation of the superficial zone cells in temporomandibular joint cartilage via the PTHrP nuclear localization sequence.

The superficial zone cells in mandibular condylar cartilage are proliferative. The present purpose was to delineate the relation of calcium-sensing receptor (CaSR) and parathyroid hormone-related peptide nuclear localization sequence (PTHrP87-139 ), and their role in the proliferation behaviors of the superficial zone cells. A gain- and loss-of-function strategy were used in an in vitro fluid flow shear stress (FFSS) model and an in vivo bilateral elevation bite model which showed mandibular condylar cartilage thickening. CaSR and PTHrP87-139 were modulated through treating the isolated superficial zone cells with activator/SiRNA and via deleting CaSR or parathyroid hormone-related peptide (PTHrP) gene in mice with the promoter gene of proteoglycan 4 (Prg4-CreERT2 ) in the tamoxifen-inducible pattern with or without additional injection of Cinacalcet, the CaSR agonist, or PTHrP87-139 peptide. FFSS stimulated CaSR and PTHrP expression, and accelerated proliferation of the Prg4-expressing superficial zone cells, in which process CaSR acted as an up-streamer of PTHrP. Proteoglycan 4 specific knockout of CaSR or PTHrP reduced the cartilage thickness, suppressed the proliferation and early differentiation of the superficial zone cells, and inhibited cartilage thickening and matrix production promoted by bilateral elevation bite. Injections of CaSR agonist Cinacalcet could not improve the phenotype caused by PTHrP mutation. Injections of PTHrP87-139 peptide rescued the cartilage from knockout of CaSR gene. CaSR modulates proliferation of the superficial zone cells in mandibular condylar cartilage through activation of PTHrP nuclear localization sequence. Our data support the therapeutic target of CaSR in promoting PTHrP production in superficial zone cartilage.

Zonal interdependence in the temporomandibular joint cartilage.

The temporomandibular joint (TMJ) cartilage is biomechanical sensitive. Cells in TMJ cartilage are zonally arranged, earlier differentiated in the super zone and late differentiated in the deep zone. The purpose was to detect the zonal interdependence in TMJ cartilage under dental biomechanical stimulations. Here, we obtained the Sox9CreER ; Rosa26tdTomato and Col10CreER ; Rosa26tdTomato mice to label super zone Sox9-expressing (Sox9+ ) or deep zone Col10-expressing (Col10+ ) cells by tdTomato (TdT), and Sox9CreER ; Rosa26DTA and Col10CreER ; Rosa26DTA mice to ablate Sox9+ or Col10+ cells selectively. These mice were subjected to unilateral anterior crossbite (UAC) or bilateral anterior elevation (BAE) dental stimulation, which promoted terminal differentiation or proliferation of TMJ chondrocytes, respectively. In both UAC and BAE models, the Sox9-TdT+ cells performed as proliferation and mature differentiation, showing as expressing Ki67 and Col-X, respectively; while the Col10-TdT+ cells performed as terminal differentiation, showing as expressing osteocalcin (OCN). In both Sox9+ - and Col10+ -cells ablation groups, there were reductions in cell number, cartilage thickness and matrix amount, subchondral bone loss, and condylar deformation. The UAC-promoted terminal differentiation was enhanced, and the BAE-promoted cellular proliferation was ruined. Impressively, when Col10+ cells were ablated, the UAC-promoted DAP3 expression, an anoikis marker, was further increased, while the BAE-suppressed DAP3 expression was instead greatly increased. These findings demonstrated that the cartilage zones function interdependently. The super zone harbors the cells that undergo differentiation to deep zone cells, the deep zone contains load-bearing matrix which is structural essential for the cells located inside or superficial.

Surface Microstructure Drives Biofilm Formation and Biofouling of Graphene Oxide Membranes in Practical Water Treatment.

Significant progress has been made previously in the research and development of graphene oxide (GO) membranes for water purification, but their biofouling behavior remains poorly understood. In this study, we investigated the biofilm formation and biofouling of GO membranes with different surface microstructures in the context of filtering natural surface water and for an extended operation period (110 days). The results showed that the relatively hydrophilic and smooth Fe(OH)3/GO membrane shaped a thin and spatially heterogeneous biofilm with high stable flux. However, the ability to simultaneously mitigate biofilm formation and reduce biofouling was not observed in the weakly hydrophilic and wrinkled Fe/GO and H-Fe(OH)3/GO membranes. Microbial analyses revealed that the hydrophilicity and roughness distinguished the bacterial communities and metabolic functions. The organic matter-degrading and predatory bacteria were more adapted to hydrophilic and smooth GO surfaces. These functional taxa were involved in the degradation of extracellular polymeric substances (EPS), and improved biofilm heterogeneity. In contrast, the weakly hydrophilic and wrinkled GO surfaces had reduced biodiversity, while unexpectedly boosting the proliferation of EPS-secreting bacteria, resulting in increased biofilm formation and aggravated biofouling. Moreover, all GO membranes achieved sustainable water purification during the entire operating period.

Ultrarobust Photothermal Materials via Dynamic Crosslinking for Solar Harvesting.

Highly efficient and mechanically durable photothermal materials are urgently needed for solar harvesting, but their development still remains challenging. Here, inspired by the hierarchically oriented architecture of natural spider silk, an ultrarobust liquid metals (LMs)/polymer composite is presented via dynamic crosslinking based on the unique mechanical deformable characteristic of LMs. Dynamically cross-linked core-shell structured LMs droplets can be squeezed along with the orientational crystallization of polymer chains during drawing, thus enabling LMs nanoparticles to be uniformly programmed in the rigid polyethylene nanofiber skeleton. The resultant composite exhibits an unprecedented combination of strong broad-band light absorption (96.9-99.3%), excellent photothermal conversion ability, remarkable mechanical property (tensile strength of 283.7 MPa, which can lift 200 000 times its own weight), and long-term structural reliability (bearing 100 000 bending cycles). A powerful and durable solar thermoelectric generator system for real-environmental solar-heat-electricity conversion is further demonstrated, providing a valuable guidance for the design and fabrication of high-performance solar-harvesting materials.

Comparison of antibacterial and antibiofilm activity of bioactive glass compounds S53P4 and 45S5.

BACKGROUND: Bone loss and deformation due to damage caused by injury or recurrent invasive infections presents a major clinical obstacle. While bone substitute biomaterials promote osseous tissue regeneration, their application in sites complicated by microbial infections such as osteomyelitis, is limited. Bioactive glass biomaterials (Bioglass) have been shown to have efficient mechanisms of repairing the integrity of bone, while inhibiting growth of a range of bacterial strains. There are several commercially available bioactive glass compounds, each with a unique chemical composition. One compound in particular, S53P4, has demonstrated antimicrobial effects in previous studies but the antimicrobial activity of the parent compound 45S5 has not been investigated. RESULTS: To assess whether antimicrobial activity is common among bioglass compounds, 45S5-the parent compound, was evaluated in comparison to S53P4 for antibacterial and antibiofilm effects against multiple strains of aerobic and anaerobic bacteria associated with various types of osteomyelitis. Experiments of antimicrobial effects in liquid cultures demonstrated that both compounds were antimicrobial against various microbial genera including S. gordonii, V. parvula, P. aeruginosa and MRSA; particles of the smallest size (32-125 µm) invariably showed the most robust antimicrobial capabilities. When employed against biofilms ecological biofilms grown on hydroxyapatite, 45S5 particles produced a stronger reduction in biofilm mass compared to S53P4 particles when considering small particle ranges. CONCLUSION: We found that 45S5 seems to be as effective as S53P4 and possibly even more capable of limiting bacterial infections. The efficacy of bioactive glass was not limited to inhibition of planktonic growth, as it also extended to bacterial biofilms. The increased antibacterial activity of 45S5 compared to S53P4 is true for a variety of size ranges.

Biodegradable Polysarcosine with Inserted Alanine Residues: Synthesis and Enzymolysis.

Polysarcosine (PSar), a water-soluble polypeptoid, is gifted with biodegradability via the random ring-opening copolymerization of sarcosine- and alanine-N-thiocarboxyanhydrides catalyzed by acetic acid in controlled manners. Kinetic investigation reveals the copolymerization behavior of the two monomers. The random copolymers, named PaS, with high molecular weights between 5.3 and 43.6 kg/mol and tunable Ala molar fractions varying from 6 to 43% can be degraded by porcine pancreatic elastase within 50 days under mild conditions (pH = 8.0 at 37 °C). Both the biodegradation rate and water solubility of PaS depend on the content of Ala residues. PaS with Ala fractions below 43% are soluble in water, while the one with 43% Ala self-assembles in water into nanoparticles. Moreover, PaS are noncytotoxic at the concentration of 5 mg/mL. The biodegradability and biocompatibility endow the Ala-containing PSar with the potential to replace poly(ethylene glycol) as a protective shield in drug-delivery.

Long-term effect of bilateral anterior elevation of occlusion on the temporomandibular joints.

OBJECTIVE: Incisors tubed prosthesis with bilateral anterior elevation (BAE) relation had been reported to stimulate the proliferative response in the mandibular condylar cartilage of mice, thus the prosthetic occlusion elevation had been proposed to treat cartilage degeneration. Currently, we aimed to detect the long-term effect of BAE on temporomandibular joints (TMJs). MATERIALS AND METHODS: Twelve 6-week-old female mice were assigned to age-matched control and BAE groups (n = 6). Micro-CT images and the macro- and micro-morphology of the mandibular condyles were analyzed at 29 weeks. RESULTS: Compared with the age-matched controls, in BAE group, there were loss of subchondral cortical bone and heavy loss of the subchondral trabecular bone at the superior sites of the TMJ condyles, but hyperostosis at the inferior sites as revealed by micro-CT images and histological slices. In BAE group, cartilage thickness and matrix area were increased with upregulated expression of type II, type X collagen, and Ki67, but the expression of cleaved caspase-3 was downregulated (all, p < 0.05). CONCLUSION: In addition to cartilage thickening, long-term BAE induces loss of the subchondral cortical bone and heavy loss of the underneath subchondral trabecular bone, but hyperostosis further underneath. Using BAE as a treatment remains double-edged.

Immune-related expression profiles of bisphosphonates-related osteonecrosis of the jaw in multiple myeloma.

Objective: To investigate the immune cellular and genomic profiles of bisphosphonates-related osteonecrosis (BRONJ) of the jaw and excavate potential small molecule drugs. Methods and materials: The genomic profile of a multiple myeloma (MM) patient with BRONJ was downloaded from Gene Expression Omnibus (GEO). The 22 immune cell subsets infiltration in the patient were predicted by cell-type identification by estimating relative subsets of RNA transcripts. In addition, the differently expressed immune-related genes (DEMGs) of BRONJ were identified, followed by Gene Ontology and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses for functional annotation. Then, potential drugs for BRONJ treatment were predicted by Connectivity Map (CMAP) based on DEGs. Results: High proportions of native CD4+T cells and M0 macrophages were observed while resting mast cells, NK cells, and eosinophils were downregulated in the BRONJ patient (P< 0.05). Resting dendritic cells and gamma delta T cells were positively correlated (r=0.93). Additionally, 36 DEMGs were screened from 336 DEGs in BRONJ expression profiles. GO enrichment analysis revealed that DEMGs were most associated with peptidyl-tyrosine modification, myeloid leukocyte migration, leukocyte chemotaxis and regulation of chemokine production(P<0.05). KEGG analysis indicated that DEMGs were mainly related to cytokine-cytokine receptor interaction, IL-17 signaling pathway and NF-Kappa B signaling pathway(P<0.05). Besides, 12 small molecule drugs were screened in MM patient with ONJ. Conclusion: The discovery of different composition of immune cell types and immune-related transcriptomes in BRONJ helps to explain the onset and development of MRONJ, which provides a novel target for BRONJ therapy.

Polyacrylic acid-b-polyptyrene covered Ni/Fe nanoparticles to remove 1,1,1-trichloroethane in water.

A new material, polyacrylic acid-b-polyptyrene (PAA-b-PS) covered Ni/Fe nanoparticles (PAA-b-PS-nZVI-Ni), was developed and evaluated for the selective dechlorination of 1,1,1-trichloroethane (1,1,1-TCA) in the presence of potential interferents. The average size of the PAA-b-PS coated Fe/Ni bimetallic nanoparticles was approximately 50 nm, which resulted from agglomeration prevention by PAA-b-PS. The removal efficiency of 1,1,1-TCA by an optimal dose with a 1.0 g/L Fe/Ni (Ni/Fe = 2 wt%) and 0.5 g/L PAA-b-PS-coated concentration was higher (87.5%) than that of bare Fe/Ni (60%). The pseudo-first-order rate constant (Kobs) of 1,1,1-TCA removal by PAA-b-PS-nZVI-Ni was 0.0142 min-1 within 240 min. Comparatively, the Kobs values of 1,1,1-TCA removal by other materials (Fe, pure bimetallic Fe/Ni, PAA-b-PS-Fe) were only 0.003, 0.0052 and 0.0103 min-1, respectively. The 1,1,1-TCA removal efficacy by PAA-b-PS-nZVI-Ni showed no obvious gap regardless of pH or various common inorganic anions (NO3-, HCO3- and SO42-) at different concentrations. However, humic acid (HA) had great influence on the degradation of 1,1,1-TCA. In conclusion, PAA-b-PS-covered Ni/Fe nanoparticles with its selectivity high effectiveness could be used as one remedial agent for the degradation of 1,1,1-TCA in water.

Metabolome and microbiome of chronic periapical periodontitis in permanent anterior teeth: a pilot study.

BACKGROUND: Periapical periodontitis is a common oral inflammatory disease that affects periapical tissues and is caused by bacteria in the root canal system. The relationship among the local metabolome, the inflammatory grade, and the type and abundance of microorganisms associated with periapical periodontitis is discussed in this study. METHODS: The inflammatory grades of periapical samples from 47 patients with chronic periapical periodontitis in permanent anterior teeth were determined based on the immune cell densities in tissues subjected to haematoxylin and eosin staining. The metabolome was evaluated using ultrahigh-performance liquid chromatography-quadrupole time-of-flight mass spectrometry, followed by principal component analysis and orthogonal partial least squares discriminant analysis. The microbiome was accessed using 16 S rRNA high-throughput sequencing. The differences in the metabolomes and microbiomes of the periapical periodontitis samples were assessed using Spearman's correlation analysis. RESULT: N-acetyl-D-glucosamine, L-tryptophan, L-phenylalanine, and 15 other metabolites were identified by the comparison between samples with severe inflammation and mild or moderate inflammation. Four amino acid metabolism pathways and one sugar metabolism pathway were associated with the inflammatory grade of periapical periodontitis. The abundance of Actinomycetes was negatively correlated with the abundance of glucosamine (GlcN), while the abundance of Tannerella was positively correlated with the abundance of L-methionine. CONCLUSIONS: The local metabolome of periapical periodontitis is correlated with the inflammatory grade. The abundance of the local metabolites GlcN and L-methionine is correlated with the abundance of the major microorganisms Actinomycetes and Tannerella, respectively.

Comparison of immune responses in guinea pigs by intranasal delivery with different nanoparticles-loaded FMDV DNA vaccine.

To compare different nanoparticle-based nasal vaccines against foot-and-mouth disease (FMD), chitosan (CS)-coated poly (lactic-co-glycolic acid) (PLGA) nanoparticles (NPs) (CS/PLGA-NPs) and amino-functionalized mesoporous silica nanoparticles (Am/MSNs) loaded with FMDV recombinant plasmid (pP12A3C/IFN-CS/PLGA-NPs and pP12A3C/IFN-Am/MS-NPs) were used to induce mucosal and systemic immune responses in guinea pigs via intranasal delivery. Simultaneously, CpG oligodeoxy nucleotides (ODNs) as a vaccine adjuvant were encapsulated in chitosan-coated poly (lactic-co-glycolic acid) nanoparticles (CpG-CS/PLGA-NPs). The pP12A3C/IFN-CS/PLGA-NPs and CpG-CS/PLGA-NPs generated displayed good morphology, high stability, mean diameters of 500 and 400 nm and encapsulation efficiencies of 83.8% and 88.4%, respectively. Data from the in vitro release assay showed that plasmid and CpG were sustainably released from nanoparticles (up to 66.73% and 64%, respectively, of the total amount loaded). Guinea pigs immunized with pP12A3C/IFN-CS/PLGA-NPs + CpG-CS/PLGA-NPs showed markedly higher mucosal, cellular and humoral immune responses than those administered pP12A3C/IFN-CS/PLGA-NPs or naked plasmid vaccine alone. FMDV-specific secretory immunoglobulin A (sIgA) antibodies in nasal washes were initially detected at 3 days post-vaccination with CS/PLGA-NPs loaded with plasmid. Guinea pigs immunized with pP12A3C/IFN-CS/PLGA-NPs also displayed higher cellular and humoral immune responses than pP12A3C-CS/PLGA-NPs and naked plasmid vaccine alone. FMDV-specific immunoglobulin G (IgG) antibodies in serum were initially detected at 5 days post-vaccination (intramuscularly) with the naked plasmid. Finally, challenge experiments 42 days post-vaccine revealed 100% protection in guinea pigs immunized with pP12A3C/IFN-CS/PLGA-NPs + CpG-CS/PLGA-NPs and pP12A3C/IFN-CS/PLGA-NPs. However, plasmid DNA was burst released from pP12A3C/IFN-Am/MS-NPs. Our attempts to use pP12A3C/IFN-Am/MS-NPs to immunize guinea pigs failed to induce immune responses. In conclusion, CpG and IFN-α adjuvant based FMD vaccines elicit protection in guinea pigs. Moreover, CS-coated PLGA NPs present an efficient and safe mucosal immune delivery system for FMDV DNA vaccine. Data from the current study provide a foundation for understanding and further evaluating protective immune responses in pigs.

The immune response to a recombinant Lactococcus lactis oral vaccine against foot-and-mouth disease virus in mice.

OBJECTIVE: Development of an effective mucosal vaccine to induce specific immune responses against Foot-and-mouth disease virus (FMDV). RESULTS: For this purpose, the FMDV VP1 gene (SPVP1) was optimized and synthesized based on the codon bias of Lactococcus lactis (L. lactis), and then incorporated in the plasmid pNZ8148. L. lactis NZ9000 containing the pNZ8148-SPVP1 recombinant plasmid was used as an oral delivery vehicle to induce anti-FMDV mucosal and systemic immune responses in mice. After confirmation that the SPVP1 protein was expressed successfully in the recombinant L. latic, the mice were orally challenged with NZ9000-pNZ8148, NZ9000-pNZ8148-SPVP1, phosphate-buffered saline as a mock infection group, or with inactivated vaccine as a positive group. Mice immunized with NZ9000-pNZ8148-SPVP1 produced high levels of mucosal secretory IgA (sIgA), antigen-specific serum IgG, IgA, and neutralizing antibodies, and developed stronger cell-mediated immune reactions and significant T spleen lymphocyte proliferation. Furthermore, the recombinant group generated much higher levels of IFN-γ, IL-2, IL-4, IL-5, and IL-10 than the other groups. CONCLUSIONS: Potent immune responses were successfully elicited in mice with FMDV VP1 delivered through L. lactis.

Development of ICAR ATRP-Based Polymerization-Induced Self-Assembly and Its Application in the Preparation of Organic-Inorganic Nanoparticles.

The functionalization and application of nano-objects generated using a polymerization induced self-assembly (PISA) procedure is becoming a focus in recent years. In this contribution, using ethanol as solvent, poly(oligo(ethylene oxide) methyl ether methacrylate) (POEOMA) as macro-initiator/stabilizer, and 2-(perfluorohexyl)ethyl methacrylate (PFHEMA) and glycidyl methacrylate (GMA) as comonomers, the initiators for continuous activator regeneration atom transfer radical polymerization (ICAR ATRP)-based PISA is realized. The lower GMA content system tends to form spheres with large diameters and heavy contrast, while the lower PFHEMA content system tends to form the spheres or short worms with small diameters. However, the system with further increased GMA content results in the failed ICAR ATRP PISA procedure with the formation of precipitates by the cross-linking reaction between pendant epoxy groups. Furthermore, using the efficient reaction between the epoxy group on GMA and thiol group on mercapto-succinic acid agent, the carboxyl groups can be introduced into the inner cavity of the nano-objects and used for incorporation with the Fe2+ and Fe3+ ions, and the organic-inorganic nanoparticles Fe3 O4 @POEOMA are finally prepared in the presence of a reductant.

Particle Mold Synthesis of Block Copolymer Janus Nanomaterials.

A particle mold synthesis of 2D Janus nanomaterials is proposed by crosslinking of copolymer self-assembled monolayers confined within the mold domains. Onto the silica (SiO2 ) particle surface, mold domains with functional groups such as imidazole are generated. The model copolymer of polyacrylic acid-block-polystyrene (PAA-b-PS) can be preferentially absorbed onto the domains via electrostatic interactions, forming a self-assembled monolayer. In a cosolvent such as tetrahydrofuran (THF), the crosslinking occurs within the whole of the PAA side. A Janus disc is thus achieved after detachment from the particle upon breaking the specific interaction. In a poor solvent, the crosslinking slowly occurs from the periphery, giving Janus nanorings. The rings evolve into discs with further crosslinking. The mold particles can be recycled to synthesize the same 2D Janus materials.

Immunogenicity and protective efficacy of recombinant proteins consisting of multiple epitopes of foot-and-mouth disease virus fused with flagellin.

Many recent studies have shown that flagellin fused to heterologous antigens can induce significantly enhanced humoral and cellular immune responses through its adjuvant activity. Therefore, in this study, two key B cell epitopes and a truncated VP1 (ΔVP1) protein from foot-and-mouth disease virus (FMDV) were expressed as flagellin fusion proteins in different patterns. Specifically, ΔVP1 and two duplicates of two key B cell epitopes (2×B1B2) were fused separately to the C-terminus of flagellin with a universal exogenous T cell epitope to construct FT (Flagellin-Truncated VP1) and FME (Flagellin-Multiple Epitopes). In addition, the D3 domain of flagellin was replaced by ΔVP1 in FME, yielding FTME (Flagellin-Truncated VP1-Multiple Epitopes). The immunogenicity and protective efficacy of the three fusion proteins as novel FMDV vaccine candidates were evaluated. The results showed that FT, FME, and FTME elicited significant FMDV-specific IgG responses at 10 µg/dose compared with the mock group (P < 0.05), with FTME producing the highest response. No significant differences in the antibody response to FTME were observed between different immunization routes or among adjuvants (ISA-206, poly(I·C), MPLA, and CpG-ODN) in mice. In addition, at 30 µg/dose, all three fusion proteins significantly induced neutralizing antibody production and upregulated the levels of some cytokines, including TNF-α, IFN-γ, and IL-12, in guinea pigs. Importantly, all three fusion proteins provided effective protective immunity against FMDV challenge in guinea pigs, though different protection rates were found. The results presented in this study indicate that the FTME fusion protein is a promising novel vaccine candidate for the future prevention and control of foot-and-mouth disease.

Bone Regeneration of Canine Peri-implant Defects Using Cell Sheets of Adipose-Derived Mesenchymal Stem Cells and Platelet-Rich Fibrin Membranes.

PURPOSE: Insufficient bone volume compromises the success rate and osseointegration of immediate implantation. The objective of the present study was to engineer bone tissue by using adipose-derived stem cell (ASC) sheets and autologous platelet-rich fibrin (PRF) to enhance new bone formation and osseointegration around dental implants. MATERIAL AND METHODS: The proliferation and osteogenic potential of ASCs treated with autologous PRF were evaluated with CCK-8 assays, alkaline phosphatase staining, and real-time quantitative polymerase chain reaction. A 3-wall bone defect around each immediate implant was generated in the mandible and randomly treated with ASC sheets plus PRF (group A), ASC sheets only (group B), PRF only (group C), or no treatment (group D). Micro-computed tomography, biomechanical tests, fluorescent bone labeling, and histologic assessments were performed to evaluate bone regeneration capacity. RESULTS: The proliferation and osteogenic potential of canine ASCs were markedly enhanced by PRF. Group A exhibited considerably more new bone formation and re-osseointegration (41.17 ± 1.44 and 55.06 ± 0.06%, respectively) than did the other 3 groups. Fluorescent labeling showed that the most rapid bone remodeling activity occurred in group A (P < .05). CONCLUSION: These results suggest that sheets of ASC combined with autologous PRF could be a promising tissue-engineering strategy for bone formation in immediate implantation.

Veillonella Catalase Protects the Growth of Fusobacterium nucleatum in Microaerophilic and Streptococcus gordonii-Resident Environments.

The oral biofilm is a multispecies community in which antagonism and mutualism coexist among friends and foes to keep an ecological balance of community members. The pioneer colonizers, such as Streptococcus gordonii, produce H2O2 to inhibit the growth of competitors, like the mutans streptococci, as well as strict anaerobic middle and later colonizers of the dental biofilm. Interestingly, Veillonella species, as early colonizers, physically interact (coaggregate) with S. gordonii A putative catalase gene (catA) is found in most sequenced Veillonella species; however, the function of this gene is unknown. In this study, we characterized the ecological function of catA from Veillonella parvula PK1910 by integrating it into the only transformable strain, Veillonella atypica OK5, which is catA negative. The strain (OK5-catA) became more resistant to H2O2 Further studies demonstrated that the catA gene expression is induced by the addition of H2O2 or coculture with S. gordonii Mixed-culture experiments further revealed that the transgenic OK5-catA strain not only enhanced the growth of Fusobacterium nucleatum, a strict anaerobic periodontopathogen, under microaerophilic conditions, but it also rescued F. nucleatum from killing by S. gordonii A potential role of catalase in veillonellae in biofilm ecology and pathogenesis is discussed here.IMPORTANCEVeillonella species, as early colonizers, can coaggregate with many bacteria, including the initial colonizer Streptococcus gordonii and periodontal pathogen Fusobacterium nucleatum, during various stages of oral biofilm formation. In addition to providing binding sites for many microbes, our previous study also showed that Veillonella produces nutrients for the survival and growth of periodontal pathogens. These findings indicate that Veillonella plays an important "bridging" role in the development of oral biofilms and the ecology of the human oral cavity. In this study, we demonstrated that the reducing activity of Veillonella can rescue the growth of Fusobacterium nucleatum not only under microaerophilic conditions, but also in an environment in which Streptococcus gordonii is present. Thus, this study will provide a new insight for future studies on the mechanisms of human oral biofilm formation and the control of periodontal diseases.

eEF1G interaction with foot-and-mouth disease virus nonstructural protein 2B: Identification by yeast two-hybrid system.

Foot-and-mouth disease virus (FMDV) is a picornavirus that causes an economically significant disease in cattle and swine. Replication of FMDV is dependent on both viral proteins and cellular factors. Nonstructural protein 2B of FMDV plays multiple roles during viral infection and replication. We investigated the roles of 2B in virus-host interactions by constructing a cDNA library obtained from FMDV-infected swine tissues, and used a split-ubiquitin-based yeast two-hybrid system to identify host proteins that interacted with 2B. We found that 2B interacted with amino acids 208-437 in the C-terminal region of the eEF1G subunit of eukaryotic elongation factor 1, which is essential for protein synthesis. The 2B-eEF1G interaction was confirmed by co-immunoprecipitation of 2B and eEF1G in HEK293T cells. Collectively, our results suggest that eEF1G interacts with the 2B protein of FMDV. The identified 2B interaction partner may help to elucidate the mechanisms of FMDV infection and replication.

Chimeric virus-like particles elicit protective immunity against serotype O foot-and-mouth disease virus in guinea pigs.

Foot-and-mouth disease (FMD) is an acute and highly contagious disease caused by foot-and-mouth disease virus (FMDV) that can affect cloven-hoofed animal species, leading to severe economic losses worldwide. Therefore, the development of a safe and effective new vaccine to prevent and control FMD is both urgent and necessary. In this study, we developed a chimeric virus-like particle (VLP) vaccine candidate for serotype O FMDV and evaluated its protective immunity in guinea pigs. Chimeric VLPs were formed by the antigenic structural protein VP1 from serotype O and segments of the viral capsid proteins (VP2, VP3, and VP4) from serotype A. The chimeric VLPs elicited significant humoral and cellular immune responses with a higher level of anti-FMDV antibodies and cytokines than the control group. Furthermore, four of the five guinea pigs vaccinated with the chimeric VLPs were completely protected against challenge with 100 50% guinea pig infectious doses (GPID50) of the virulent FMDV strain O/MAY98. These data suggest that chimeric VLPs are potential candidates for the development of new vaccines against FMDV.

Identification and characterization of a haem biosynthesis locus in Veillonella.

Haemin/haem is one of the essential nutrients required by periodontopathogens such as Porphyromonas gingivalis to grow in vitro. In the oral cavity, this nutrient is believed to be provided by the crevicular fluid, a serum-like exudate produced during gum inflammation. However, P. gingivalis is also present in the healthy dental biofilm where inflammation is absent. This study was designed to answer the question: what organism(s) in the healthy dental biofilm provides haemin/haem to those periodontal pathogens? We report here that veillonellae, a group of bridging species in dental biofilm development, harbour a complete gene cluster for haem biosynthesis. Haemin production was detected from cell lysate, suggesting that the haem biosynthesis pathway is functional in veillonellae. Using the only transformable strain Veillonella atypica OK5, we inactivated specific key genes in the haem biosynthesis pathway. Inactivation of hemE, encoding the enzyme uroporphyrinogen decarboxylase, not only abolished haemin production but also significantly decreased OK5-supported growth of P. gingivalis. A luciferase gene reporter to the hemEHG operon demonstrated up-regulation of operon expression by P. gingivalis. Analysis of all sequenced genomes of oral bacteria in the HOMD database identified three genera (Veillonella, Propionibacterium and Aggregatibacter) that have a complete haem biosynthesis gene cluster, suggesting that they all could be potential haemin/haem providers in the dental biofilm.