Conserved antigen structures and antibody-driven variations on foot-and-mouth disease virus serotype A revealed by bovine neutralizing monoclonal antibodies.

Foot-and-mouth disease virus (FMDV) serotype A is antigenically most variable within serotypes. The structures of conserved and variable antigenic sites were not well resolved. Here, a historical A/AF72 strain from A22 lineage and a latest A/GDMM/2013 strain from G2 genotype of Sea97 lineage were respectively used as bait antigen to screen single B cell antibodies from bovine sequentially vaccinated with A/WH/CHA/09 (G1 genotype of Sea97 lineage), A/GDMM/2013 and A/AF72 antigens. Total of 39 strain-specific and 5 broad neutralizing antibodies (bnAbs) were isolated and characterized. Two conserved antigenic sites were revealed by the Cryo-EM structures of FMDV serotype A with two bnAbs W2 and W125. The contact sites with both VH and VL of W125 were closely around icosahedral threefold axis and covered the B-C, E-F, and H-I loops on VP2 and the B-B knob and H-I loop on VP3; while contact sites with only VH of W2 concentrated on B-B knob, B-C and E-F loops on VP3 scattering around the three-fold axis of viral particle. Additional highly conserved epitopes also involved key residues of VP158, VP1147 and both VP272 / VP1147 as determined respectively by bnAb W153, W145 and W151-resistant mutants. Furthermore, the epitopes recognized by 20 strain-specific neutralization antibodies involved the key residues located on VP3 68 for A/AF72 (11/20) and VP3 175 position for A/GDMM/2013 (9/19), respectively, which revealed antigenic variation between different strains of serotype A. Analysis of antibody-driven variations on capsid of two virus strains showed a relatively stable VP2 and more variable VP3 and VP1. This study provided important information on conserve and variable antigen structures to design broad-spectrum molecular vaccine against FMDV serotype A.

Two Cross-Protective Antigen Sites on Foot-and-Mouth Disease Virus Serotype O Structurally Revealed by Broadly Neutralizing Antibodies from Cattle.

Foot-and-mouth disease virus (FMDV) is a highly contagious virus that infects cloven-hoofed animals. Neutralizing antibodies play critical roles in antiviral infection. Although five known antigen sites that induce neutralizing antibodies have been defined, studies on cross-protective antigen sites are still scarce. We mapped two cross-protective antigen sites using 13 bovine-derived broadly neutralizing monoclonal antibodies (bnAbs) capable of neutralizing 4 lineages within 3 topotypes of FMDV serotype O. One antigen site was formed by a novel cluster of VP3-focused epitopes recognized by bnAb C4 and C4-like antibodies. The cryo-electron microscopy (cryo-EM) structure of the FMDV-OTi (O/Tibet/99)-C4 complex showed close contact with VP3 and a novel interprotomer antigen epitope around the icosahedral 3-fold axis of the FMDV particle, which is far beyond the known antigen site 4. The key determinants of the neutralizing function of C4 and C4-like antibodies on the capsid were ßB (T65), the B-C loop (T68), the E-F loop (E131 and K134), and the H-I loop (G196), revealing a novel antigen site on VP3. The other antigen site comprised two group epitopes on VP2 recognized by 9 bnAbs (B57, B73, B77, B82, F28, F145, F150, E46, and E54), which belong to the known antigen site 2 of FMDV serotype O. Notably, bnAb C4 potently promoted FMDV RNA release in response to damage to viral particles, suggesting that the targeted epitope contains a trigger mechanism for particle disassembly. This study revealed two cross-protective antigen sites that can elicit cross-reactive neutralizing antibodies in cattle and provided new structural information for the design of a broad-spectrum molecular vaccine against FMDV serotype O. IMPORTANCE FMDV is the causative agent of foot-and-mouth disease (FMD), which is one of the most contagious and economically devastating diseases of domestic animals. The antigenic structure of FMDV serotype O is rather complicated, especially for those sites that can elicit a cross-protective neutralizing antibody response. Monoclonal neutralization antibodies provide both crucial defense components against FMDV infection and valuable tools for fine analysis of the antigenic structure. In this study, we found a cluster of novel VP3-focused epitopes using 13 bnAbs against FMDV serotype O from natural host cattle, which revealed two cross-protective antigen sites on VP2 and VP3. Antibody C4 targeting this novel epitope potently promoted viral particle disassembly and RNA release before infection, which may indicate a vulnerable region of FMDV. This study reveals new structural information about cross-protective antigen sites of FMDV serotype O, providing valuable and strong support for future research on broad-spectrum vaccines against FMD.

Specific microbes of saliva and vaginal fluid of Guangdong Han females based on 16S rDNA high-throughput sequencing.

Vaginal fluid and saliva are of great importance in forensic sciences. The identification of vaginal fluid or saliva is especially important in criminal cases. Microbes are considered as a promising marker for the identification of body fluids. In this study, 18 salivary fluids and 18 vaginal fluid samples were collected from 18 healthy women of the Han population in Guangdong province, China. The microbes of the above samples were analyzed by 16S rDNA high-throughput sequencing. The results showed that the microbes whose proportions are over 1% in saliva samples distributed across 12 genera and 57 operational taxonomic units (OTUs), and in vaginal fluid distributed across 4 genera and 9 OTUs. The microbes that dominated in saliva were quite different from those dominated in vaginal fluids. The linear discriminant analysis (LDA) effect size (LEfSe) algorithm was used to screen out the specific microbes of the studied samples, and the results showed that the specific microbes in saliva samples are Haemophilus parainfluenzae, Veillonella parvula, and Aggregatibacter segnis, while in vaginal fluid is Lactobacillus iners.

Microplastics enrichment characteristics of antibiotic resistance genes and pathogens in landfill leachate.

Microplastics (MPs) pollution is a pressing environmental issue for aquatic ecosystems. Landfill leachate is an important contributor of MPs and antibiotic resistant genes (ARGs). However, there are few studies on the colonization of ARGs and pathogens on MPs in leachate. This study conducted incubation experiments with polyethylene terephthalate (PET) and polypropylene (PP) MPs in landfill leachate which were about 3-5 years old (PL) and 5-10 years old (AL). After incubation, the bacterial cells colonized and grew on the surface of MPs, inducing the increase of oxygenated oxygen functional groups (e.g., hydroxyl, carbonyl) on the MPs surface. Real-time PCR indicated that MPs selectively enriched ARGs, such as genes tetM, tetC, mcr-1, aac(6')-Ib-cr, blaTEM and blaSHV in leachate. The diversity of bacterial communities on MPs was significantly increased in AL leachate, but decreased in PL leachate. The differences in bacterial communities in MPs biofilms were related to the type of MPs. Compared with AL leachate, the abundance of Chloroflexi increased by 15.7% on the PET, and the abundance of Acidobacteriota increased by 6.23 fold on the PP. The abundance of Firmicutes increased from 20.7% in PL leachate to 65.8% and 60.7% on PET and PP, respectively. Additionally, pathogens were observed to be more abundant on MPs compared to leachate. In particular, pathogens (Staphylococcus, Streptococcus, Enterobacter and Rhodococcus) associated with sul1 and sul2 were generally present at higher levels on MPs than in the surrounding leachate. These results provide significant implications for understanding the health risk of MPs in the environment.

The effects of microplastics and nanoplastics on nitrogen removal, extracellular polymeric substances and microbial community in sequencing batch reactor.

Wastewater treatment plants can be nanoplastics (NPs) and microplastics (MPs) sinks and sources. The effects of NPs and MPs on nitrogen removal and extracellular polymeric substances (EPS) during activated sludge process need further investigation. Results showed that polystyrene NPs (NPS) and 100 mg/L polystyrene MPs (MPS) decreased the specific nitrate reduction rate, resulting in nitrate accumulation. The negative effects on functional genes involved in denitrification (narG, napA, nirS and nosZ) were the main mechanism. NPS stimulated EPS secretion, but MPS inhibited it. NPS and MPS increased the ratio of protein to polysaccharide except for 10 mg/L MPS and changed the secondary structure of protein in EPS, affecting flocculation ability of activated sludge. The changes of microbial abundance in activated sludge could be the main factor to the alterations of EPS and nitrogen removal. These results may facilitate understanding the impacts of NPs and MPs on wastewater treatment processes.

Adsorption of tetracycline and Cd(II) on polystyrene and polyethylene terephthalate microplastics with ultraviolet and hydrogen peroxide aging treatment.

Microplastics (MPs) could serve as vectors of antibiotics and heavy metals through sorption and desorption. However, the combined adsorption process of antibiotics and heavy metals on aged MPs has rarely been studied. In this study, combined adsorption/desorption of tetracycline (TC) and Cd(II) on/from polystyrene (PS) and polyethylene terephthalate (PET) MPs, as well as ultraviolet (UV) and H2O2 aged MPs, was investigated. The specific surface areas of the MPs increased after UV and H2O2 aging. Adsorption experiments showed that the pseudo-second-order kinetic model and Freundlich model fitted adsorption of TC and Cd(II) on all of the MPs. The adsorption capacities of TC and Cd(II) were higher on aged MPs than on the pristine MPs, especially on H2O2 treated MPs. TC adsorption on the MPs was hardly affected by Cd(II), and Cd(II) adsorption was not significantly affected by TC when the solution pH value was below 8.0. Cd(II) slightly enhanced TC adsorption on the MPs at pH 8.0, especially on the aged MPs. The TC adsorption capacities increased with increasing pH, reaching a maximum at pH 5.0 or 6.0, and they then decreased, while the largest level of Cd(II) adsorption was at approximately pH 6.0. Adsorption of TC and Cd(II) on the pristine and aged MPs was thermodynamically favorable and spontaneous. The trend of the desorption rates of TC and Cd(II) from the MPs in different background solutions was ultrapure water < surface water < simulated gastric fluid. The desorption rates of TC and Cd(II) from the aged MPs were lower than those from the pristine MPs. The results revealed the mechanism of the TC and Cd(II) combined adsorption process on aged MPs, which will provide insight for understanding the aging process and its potential effects on sorption and desorption of antibiotics and heavy metals in the real environment.

[Adsorption of Fulvic Acid on Virgin and Aging Microplastics].

Due to the wide distribution and strong adsorption ability of microplastics (MPs) for organic matter in aquatic environments, the interaction between MPs and natural organic matter (NOM) cannot be ignored. In this study, virgin and aging polyamide 66 (PA66) and polypropylene (PP) MPs were used to adsorb fulvic acid (FA) in order to understand the effect of MPs on NOM. The results indicated that the kinetics experimental data of FA adsorption on virgin and aging MPs well fitted the pseudo-second-order model (R2>0.94), and the adsorption equilibrium was reached at 48 h. Compared to that of PP, the adsorption capacity of FA on PA66 were relatively higher, and the aging process improved the adsorption ability of MPs for FA. Freundlich models were well fitting with the adsorption isotherms experimental data compared to Langmuir models, indicating that the adsorption of FA on the virgin and aging MPs was a multi-layer heterogeneous physical process. The thermodynamics analysis revealed that the adsorption was spontaneous and endothermic. With the increase in pH, the adsorption capacity of FA first decreased and then increased. The desorption experiment indicated that the FA desorbed from the tested MPs in ultrapure water obtained higher desorption rates than that in surface water, and the desorption rates of aging MPs were less than that of the corresponding virgin ones. The aging process had a great influence on the structure of MPs, which resulted in a distinct increase in surface area and roughness of MPs, but slightly affected functional groups. Specific surface area and polarity of MPs were the main influencing factors for the adsorption process, and the main mechanism of FA adsorption on the tested MPs was hydrophobic and π-π interactions.

Straw mulching for enhanced water use efficiency and economic returns from soybean fields in the Loess Plateau China.

Water shortages threaten agricultural sustainability in the semi-arid areas of the Loess Plateau. Judicious mulching management can improve water conservation practices to alleviate this issue while increasing crop productivity. We investigated the effect of straw strip mulching and film mulching on soil water consumption, temperature, growth, grain yield, and economic income of soybean [Glycine max(Linn.) Merr.] from 2017 to 2018 in Qingyang on the semi-arid Loess Plateau in China using four treatments: (a) alternating ridges and furrows with ridges mulched with white polyethylene film (PMP), (b) alternating flat and bare land with only the plat mulched by white polyethylene film (PMF), (c) alternating strips mulched with maize (Zea mays L.) straw (SM), and (d) traditional land planting without mulching (CK). The mulching treatments (PMP, PMF, and SM) increased soil water consumption and soil water use efficiency. The SM, PMF, and PMP treatments had 12.3-12.5, 16.8-22.1, and 23.2-24.2 mm higher soil water consumption (0-120 cm depth) than CK, most of which occurred in the 60-120 cm soil layer. Compared with CK, PMP and PMF significantly increased soil temperature by 1.30-1.31 °C and 0.76-1.00 °C, soybean grain yield by 38.6-39.0 % and 38.8-44.2 %, and water use efficiency (WUE) by 27.7-32.8 % and 30.8-37.5 %, respectively, while SM significantly decreased soil temperature by 0.96-1.15 °C, and increased grain yield by 21.8-25.4 % and WUE by 16.9-21.9 %. PMP and PMF did not significantly change soil water consumption, WUE, or grain yield. The SM treatment increased net income by 501.3-691.7 and 1914.5-2244.9 CNY ha-1 relative to PMP and CK, respectively, but PMF and SM did not significantly differ. Therefore, the SM system could help increase grain yields and economic returns in dryland soybean production, avoiding the adverse effects of the increasingly popular plastic mulching approach.

[Sorption Behaviors of Copper Ions and Tetracycline on Microplastics in Aqueous Solution].

The interaction between microplastics, heavy metals, and antibiotics can lead to combined pollution, which could result in greater environmental damage. The pathway and mechanism of the interaction between microplastics, heavy metals, and antibiotics are the preconditions for evaluating the associated environmental risk; however, these are not well understood. As probe sorbates, the sorption behaviors of copper ions (Cu2+) and tetracycline (TC) on two microplastics [high density polyethylene (HPDE) and general-purpose polystyrene (GPPS)] in aqueous solution were investigated and the welding theory with relevant experimental results were discussed. The adsorption capacity of HDPE was greater than that of GPPS in a single Cu solution, whereas the reverse situation occurred in a single TC solution. Moreover, the adsorption capacity of the microplastics in a Cu2+-TC binary solution was larger than that in the single solutions. The pseudo-second-order kinetic models to describe the adsorption process were reasonable and the entire process could be divided into two phases:surface adsorption and internal diffusion. The Langmuir model provided a better fit of the data than did the Freundlich model. In the single solutions, the saturated adsorption amounts of Cu2+ and TC were 0.178 µmol·g-1 and 0.257 µmol·g-1, respectively, for GPPS, and 0.334 µmol·g-1 and 0.194 µmol·g-1, respectively, for HDPE. In the binary solution, the corresponding numerical values were 0.529 µmol·g-1 and 0.411 µmol·g-1, respectively, for GPPS and 0.471 µmol·g-1 and 0.341 µmol·g-1, respectively, for HDPE. The variations in the surface morphological characteristics and chemical functional groups were the main reasons for the difference in the adsorption behavior of microplastics. The variation of the pH of the adsorption system could change the existing forms and surface electrical properties of microplastics and adsorbed objects, and subsequently affected the equilibrium adsorption capacity. When the ambient temperature was in the range of 15 to 35℃, increasing the temperature was unfavorable for the adsorption process. Cu2+ and TC could produce a synergistic effect under the conditions of coexistence. The formation of complexes and bridging make Cu2+ and TC more easily adsorbed by microplastics.

Powder Activated Carbon Pretreatment of a Microfiltration Membrane for the Treatment of Surface Water.

This study focused on the effect of powder activated carbon (PAC) adsorption on microfiltration (MF) membrane performance. The results showed that PAC pretreatment offered high organic matter removal rates for both dissolved organic carbon (DOC) and ultraviolet absorbance at 254 nm (UV254) during 10-200 mg/L PAC dosage. The removal efficiencies of organic matter by MF membrane filtration decreased with the increase of organic matter removal rate by PAC adsorption. PAC mainly removed organic matter of about 3 kDa molecular weight (MW). MF membrane maintained more than 5 kDa MW organic matter on the membrane after PAC adsorption. The results of membrane filtration indicated that PAC pretreatment slightly promoted membrane flux, regardless of PAC dosage. It seems that the organic matter fouling membrane was concentrated in more than 3 kDa MW. PAC removed markedly less than 3 kDa MW organic matter and had less effect on more than 3 kDa organic matter. Thus, PAC cannot reduce membrane fouling.

[Effect of ozone/coagulation pretreatment on membrane fouling reduction].

In order to investigate the effect of ozone and coagulation pretreatments on organic matter and MF membrane filtration, pretreated Huangpu River surface water was filtrated by MF membrane. The results showed that there were the optimal dosages of ozone and coagulant made maximum membrane flux. The result of membrane fouling reduction by coagulation was better than that by ozone, which was relative to character of organic matter removed by two pretreatment processes. Organics in Huangpu River water mostly concentrates in relative molecule mass (Mr) ranging 3 x 10(3)-5 x 10(3). Research on the chemical cleaning of the fouled membrane indicated that fouling organic substance concentrated about Mr 4.5 x 10(3). Removals of Mr 3 x 10(3) organic matter are higher than Mr 5 x 10(3) organic matter by ozone oxidation. Coagulation process can remove 5 x 10(3) high relative molecular mass organic matter effectively. Removal of these organics fouled membrane by coagulation was better than that by ozone, thereby to effectively reduce membrane fouling.

[Effect of preozonation on microfiltration for Huangpu River].

This study investigated the effect of preozonation on organic matter and microfiltration membrane filtration, Huangpu River surface water ozonated was filtrated by MF membrane. The results show that highest rejection efficiency of DOC and UVr by ozone are 10% and 71% respectively during 0.5-3.0 mg/L ozone dosage. With increasing of ozone concentration, organic substances of 2 x 10(3)-7 x 10(3) reduce gradually, while organic matter of which less than 0.5 x 10(3) change slightly. Ozone oxidizes more hydrophobic fraction to hydrophilic one and only few to inorganic matter. Changes of organic matter composition affect membrane filtration resistance, thereby improve membrane flux. There is the optimal dosage with ozone of 1.5 mg/L made membrane flux maximum in the range of 0.5-3.0 mg/L ozone dosage. The reason is change of organic matter composition which made membrane filtration resistance minimum in the ozone dosage of 1.5 mg/L.

The feature-based modeling of standard tooth in a dental prosthetic database.

This paper presents a feature-based approach that creates standard teeth models in database to provide the topological construction of the model for dental CAD. The approach arises from the basic idea that every tooth has its individual features and can be implemented in three steps. In the first step, the features on teeth are defined according to the oral anatomy. In the second step, Nurbs surfaces are applied so that the forms of standard teeth can be represented via establishing the topological relationship of features. Here, these feature-based surfaces have the capability of being local controlled that guarantees the accuracy of dental design. In the last step, feature curves are presented to describe the topological construction of dental ridges and grooves. Through these curves, the occlusal surface can be changed globally, simplifying dental design. It is finished with the establishment of standard database composed of 28 standard models constructed by feature-based surfaces and feature curves.