Molecular Dynamics Simulation Research on Fe Atom Precipitation Behaviour of Cu-Fe Alloys during the Rapid Solidification Processes.

To explore the crystalline arrangement of the alloy and the processes involving iron (Fe) precipitation, we employed molecular dynamics simulation with a cooling rate of 2 × 1010 for Cu100-XFeX (where X represents 1%, 3%, 5%, and 10%) alloy. The results reveal that when the Fe content was 1%, Fe atoms consistently remained uniformly distributed as the temperature of the alloy decreased. Further, there was no Fe atom aggregation phenomenon. The crystal structure was identified as an FCC-based Cu crystal, and Fe atoms existed in the matrix in solid solution form. When the Fe content was 3%, Fe atoms tended to aggregate with the decreasing temperature of the alloy. Moreover, the proportion of BCC crystal structure exhibited no obvious changes, and the crystal structure remained FCC-based Cu crystal. When the Fe content was between 5% and 10%, the Fe atoms exhibited obvious aggregation with the decreasing temperature of the alloy. At the same time, the aggregation phenomenon was found to be more significant with a higher Fe content. Fe atom precipitation behaviour can be delineated into three distinct stages. The initial stage involves the gradual accumulation of Fe clusters, characterised by a progressively stable cluster size. This phenomenon arises due to the interplay between atomic attraction and the thermal motion of Fe-Fe atoms. In the second stage, small Fe clusters undergo amalgamation and growth. This growth is facilitated by non-diffusive local structural rearrangements of atoms within the alloy. The third and final stage represents a phase of equilibrium where both the size and quantity of Fe clusters remain essentially constant following the crystallisation of the alloy.

Coupling effect of key factors on ecosystem services in border areas: a study of the Pu'er region, Southwestern China.

The coupling effects created by transboundary and local factors on ecosystem services are often difficult to determine. This poses great challenges for ecosystem protection and management in border areas. To decrease uncertainty, it is crucial to quantify and spatialize the impact multiple factors have on ecosystem services within different scenarios. In this study, we identified key transboundary and local factors from a set of 15 sorted factors related to four main ecosystem services. We employed a Bayesian Network-Geographic Information System (BN-GIS) model to simulate 90 scenarios with multiple factors combinations, quantifying and spatializing the coupling effects on the main ecosystem services. These simulations were conducted in the Pu'er region, which is situated alongside three countries, and serves as a representative border area in southwest China. The results showed that: (1) The coupling effects of multiple factors yield significant variations when combined in different scenarios. Managers can optimize ecosystem services by strategically regulating factors within specific areas through the acquisition of various probabilistic distributions and combinations of key factors in positive coupling effect scenarios. The outcome is a positive coupling effect. (2) Among the four main ecosystem services in the Pu'er region, food availability and biodiversity were affected by key transboundary and local factors. This suggests that the coupling of transboundary and local factors is more likely to have a significant impact on these two ecosystem services. Of the 45 combination scenarios on food availability, the majority exhibit a negative coupling effect. In contrast, among the 45 combination scenarios on biodiversity, most scenarios have a positive coupling effect. This indicates that food availability is at a higher risk of being influenced by the coupling effects of multiple factors, while biodiversity faces a lower risk. (3) Transboundary pests & diseases, application of pesticides, fertilizer & filming , population density, and land use were the key factors affecting food availability. Bio-invasion, the normalized differential vegetation index, precipitation, and the landscape contagion index were the key factors affecting biodiversity. In this case, focusing on preventing transboundary factors such as transboundary pests & disease and bio-invasion should be the goal. (4) Attention should also be paid to the conditions under which these transboundary factors combine with local factors. In the areas where these negative coupling effects occur, enhanced monitoring of both transboundary and local factors is essential to prevent adverse effects.

Identification of Multi-Dimensional Relative Poverty and Governance Path at the Village Scale in an Alpine-Gorge Region: A Case Study in Nujiang, China.

Absolute poverty has historically been solved in China, and the focus on poor areas has shifted to addressing relative poverty. To realize the organic combination of the rural revitalization strategy and relative poverty governance, multi-dimensional relative poverty identification and governance path research at the village scale in an alpine-gorge region is required. For this study, the Nujiang Lisu Autonomous Prefecture's research area in a typical alpine-gorge was chosen. This paper constructed an evaluation index system for the rural regional system based on location conditions, ecological environment, productive resources, economic base, and public service, based on the theory of multi-dimensional regional poverty and the human-land relationship. The level of poverty, types of poverty, and spatial distribution characteristics of 255 administrative villages were systematically analyzed, and poverty governance paths were proposed. The results show that: (1) There were 215 multi-dimensional relative poverty villages in Nujiang Prefecture, accounting for 84.31% of the total. The relatively poor villages with poverty grades I and II, which are classified as mild poverty, account for 77.21% of all poor villages; this demonstrated that the relatively poor villages in Nujiang Prefecture had a high potential for poverty alleviation. (2) There are 19 different types of constraints in poor villages. Grades III and IV poor villages were mostly found in high-altitude areas. The economic foundation was very weak, the infrastructure was imperfect, the land use type was relatively single, and traffic conditions were relatively backward. (3) The priority model accounted for 16.67% of relative poverty governance, the steady improvement accounted for 28.79%, and key support accounted for 54.54%. Relative poverty governance paths for various counties have been proposed, including rural revitalization priority demonstration, ecological environment governance, eco-tourism, modern agriculture + mountain agroforestry, and improved people's livelihood and well-being. The findings provided scientific support and direction for future research on the mode and course of relative poverty governance in poor villages in the alpine-gorge area, as well as the rural revitalization strategy's implementation.

High-quality reconstruction of China's natural streamflow.

Reconstruction of natural streamflow is fundamental to the sustainable management of water resources. In China, previous reconstructions from sparse and poor-quality gauge measurements have led to large biases in simulation of the interannual and seasonal variability of natural flows. Here we use a well-trained and tested land surface model coupled to a routing model with flow direction correction to reconstruct the first high-quality gauge-based natural streamflow dataset for China, covering all its 330 catchments during the period from 1961 to 2018. A stronger positive linear relationship holds between upstream routing cells and drainage areas, after flow direction correction to 330 catchments. We also introduce a parameter-uncertainty analysis framework including sensitivity analysis, optimization, and regionalization, which further minimizes biases between modeled and inferred natural streamflow from natural or near-natural gauges. The resulting behavior of the natural hydrological system is represented properly by the model which achieves high skill metric values of the monthly streamflow, with about 83% of the 330 catchments having Nash-Sutcliffe efficiency coefficient (NSE) > 0.7, and about 56% of the 330 catchments having Kling-Gupta efficiency coefficient (KGE) > 0.7. The proposed construction scheme has important implications for similar simulation studies in other regions, and the developed low bias long-term national datasets by statistical postprocessing should be useful in supporting river management activities in China.

Review on Preparation Technology and Properties of Refractory High Entropy Alloys.

Refractory high entropy alloys have broad application prospects due to their excellent comprehensive properties in high temperature environments, and they have been widely implemented in many complex working conditions. According to the latest research reports, the preparation technology of bulk and coating refractory high entropy alloys are summarized, and the advantages and disadvantages of each preparation technology are analyzed. In addition, the properties of refractory high entropy alloys, such as mechanical properties, wear resistance, corrosion resistance, oxidation resistance, and radiation resistance are reviewed. The existing scientific problems of refractory high entropy alloys, at present, are put forward, which provide reference for the development and application of refractory high entropy alloys in the future, especially for plasma-facing materials in nuclear fusion reactors.

Diversity of porcine reproductive and respiratory syndrome virus in Shandong, China.

Porcine reproductive and respiratory syndrome virus (PRRSV) is one of the most economically significant pathogens in swine industry of China. To study infection and genetic variation of PRRSV, 637 tissue samples were collected from diseased pigs in Shandong, and then subjected to detection of PRRSV. The nsp2 and ORF5 genes were sequenced for investigation of variations and phylogenetic analysis. The results showed that positive rate of PRRSV was 9.58% in the collected samples. Phylogenetic analysis of GP5 showed that these strains were clustered into two lineages (1 and 8) indicating different genotypes of PRRSV were circulating in Shandong province. Meanwhile, sequence analysis Of nsp2 showed that the PRRSV strains with 30 amino acids deletions were dominant. Moreover, novel pattern of recombination/deletion and insertion in nsp2 was observed in these strains, indicating that novel PRRSV strains with different patterns of deletions or insertions in nsp2 are emerging in China. All the results suggested that continuous surveillance of PRRSV in China is warranted. Keywords: PRRSV; GP5; nsp2; genetic analysis; Shandong.

Molecular Dynamics Research on the Impact of Vacancies on Cu Precipitation in BCC-Fe.

The molecular dynamics (MD) simulation method was used to explore the impact of vacancy concentration (0 at%, 0.1 at% and 0.2 at%) on the diffusion and precipitation rate of Cu atoms in the Fe-3.5Cu alloy and the growth of Cu precipitation during the aging process of the alloy. The mechanism of the influence of Cu precipitation relative to the tensile properties of Fe-3.5Cu alloy was investigated. The results showed that the presence of vacancies will promote the diffusion and precipitation of Cu atoms in the Fe-3.5Cu alloy, but the diffusion and precipitation rate of Cu atoms does not always increase with the increase in vacancies. In the alloy containing 0.2 at% vacancies, the diffusion and precipitation rate of Cu atoms is lower than that in the alloy containing 0.1 at% vacancies. During the aging process, when the alloy contains no vacancies, no Cu precipitates will be produced. In the alloy containing 0.1 at% vacancies, the size of the Cu precipitates produced is larger than the size of the Cu precipitates produced in the alloy containing 0.2 at% vacancies, but the number of precipitates is less than that in the alloy with 0.2 at% vacancies. During the tensile process, the Cu precipitates will promote early occurrence of phase transition of the internal crystal structure in the Fe-3.5Cu alloy system, and lead to the generation of vacancy defects in the system, thus weakening the yield strength and strain hardening strength of the alloy.

Genetic characterization, mechanisms and dissemination risk of antibiotic resistance of multidrug-resistant Rothia nasimurium.

Rothia nasimurium is part of the commensal flora of humans and other animals and has recently received increasing attention for its multidrug-resistance (MDR) and pathogenicity. Currently, no systematic reports characterize the genetics, mechanisms, and dissemination risks of antibiotic resistance in MDR R. nasimurium. Here, we present the first report outlining a MDR strain of R. nasimurium, E1706032a, isolated from ducks exhibiting clinical sickness. Phylogenetic analysis indicates that E1706032a mostly likely originated in the commensal bacteria of Amazona aestiva in Florida. E1706032a is resistant to beta-lactams, aminoglycosides, macrolides, sulfonamides, fluoroquinolones, rifamycins, tetracyclines, lincosamides and chloramphenicol. Genetic sequences related to drug resistance were detected, including resistance genes (aac(6')-Ib, ant(3″)-Ia, sul1, dfrA7, erm(X)), efflux pumps (tetZ, qacEΔ1, cmx, phosphate ABC transporter ATP-binding protein), and resistance-related proteins (hydrolase of the metallo-beta-lactamase (MBLs), mycinamicin resistance protein (myrA), DNA-directed RNA polymerase subunit beta (rpoB) variants, etc). E1706032a carries an IS481-like element, IS5564 and IS6-like elements, and IS6100 along with several novel transposases of the IS3 family. E1706032a also carries the class 1 integron gene IntI1, which is downstream adjacent to the gene cassettes aac(6')-Ib, tetZ, dfrA27, ant(3″)-Ia, qacEΔ1, sul1, cmx and upstream adjacent to gene tnpA of IS6100. Genetic analysis suggests that E1706032a carries wide antibiotic resistance and dissemination potential through movable elements and thus has the potential to cause difficult-to-treat infections in animals and humans. The dissemination of E1706032a from parrots in Florida to ducks in eastern China indicates a cross-regional public health infection risk that should be evaluated for risk of global spreading.

Recombinant Lactobacillus acidophilus expressing S1 and S2 domains of porcine epidemic diarrhea virus could improve the humoral and mucosal immune levels in mice and sows inoculated orally.

Porcine epidemic diarrhea (PED) is a highly contagious intestinal infectious disease caused by porcine epidemic diarrhea virus (PEDV), which is characterized by a high mortality rate in piglets. Since 2012, a remarkable growth in PED outbreaks occurred in many pig farms in China, landing a heavy blow on the pig industry. In order to develop a new effective vaccine for the current PEDV, oral vaccines were generated by transferring eukaryotic expression recombinant plasmids carrying the S1 and S2 (antigenic sites of the S protein) epitopes of PEDV into a swine-origin Lactobacillus acidophilus (L. acidophilus). After oral immunization of the BALB/c mice, higher levels of anti-PEDV specific IgG and SIgA antibodies and cellular immune responses were detected in mice orally administered with the recombinant L. acidophilus-S1 compared to the L. acidophilus-S2. Furthermore, L. acidophilus-S1 was used to inoculate the pregnant sows orally and the results showed that the recombinant L. acidophilus-S1 could elicit a specific systemic and mucosal immune response. In summary, our study demonstrated that oral immunization with L. acidophilus-S1 could improve the humoral and mucosal immune levels in sows and would be a promising candidate vaccine against PEDV infection in piglets.

A porcine alveolar macrophage cell line stably expressing CD163 demonstrates virus replication and cytokine secretion characteristics similar to primary alveolar macrophages following PRRSV infection.

The in vitro investigation of cytokine secretion induced by porcine reproductive and respiratory syndrome virus (PRRSV) requires porcine alveolar macrophages (PAMs) and their interaction with immunocytes. However, immortalized monoclonal PAMs (mPAMs) are non-permissive for PRRSV infection. The porcine CD163 receptor isolated from primary PAMs (pPAMs) confers susceptibility to PRRSV infection; thus, this approach could be used to establish a novel cell line to facilitate the exploration of PRRSV infection kinetics. Here, we amplified the coding region of the CD163 gene from pPAMs and integrated it into an mPAM line using a lentivirus expression system. After verification, the monoclonal PAM cell line stably expressing CD163 (mPAM-CD163-GFP) was infected with either the highly pathogenic PRRSV strain JXA1 or the classical PRRSV strain SD1, which produced high infectious titers of progeny virus reaching > 109 copies/mL or a 50 % tissue culture infective dose of 105.5 over at least 100 cell generations. We also investigated cytokine and Toll-like receptor expression in infected mPAM-CD163-GFP cells and pPAMs. The mPAM-CD163-GFP cell line showed similar patterns of viral replication and cytokine secretion compared with pPAMs, so it may be extremely useful for replacing primary cells for in vitro investigations of the mechanisms of cytokine secretion and interactions between PRRSV-infected PAMs and immunocytes.

Adjuvant effects of L. acidophilus LW1 on immune responses to the foot-and-mouth disease virus DNA vaccine in mice.

The adjuvant effects of Lactobacillus acidophilus on DNA vaccination are not fully understood. It has been hypothesized that swine-derived Lactobacillus acidophilus SW1 (LASW1) could function as an immune adjuvant to enhance antigen-specific immune responses after foot-and-mouth disease (FMD) DNA vaccination in mice. To evaluate the effect of oral LASW1 on the immune response to a DNA vaccine (pRC/CMV-vp1) harboring FMD VP1 gene, anti-FMDV antibody and its isotypes, T-cell proliferation, and cytokine detection were investigated. The results showed that LASW1 was able to enhance FMDV-specific antibody levels and FMDV-neutralizing antibodies. After a booster vaccine, the anti-FMDV antibody titers and FMDV-neutralizing antibodies levels induced by pRC/CMV-vp1 were higher in mice treated with LSAW1 than in the group immunized with pRC/CMV-vp1 alone (the control). Using T-cell proliferation, the stimulation index of the LASW1 group was significantly higher in response to ConA and 146S antigen (P<0.05) than in the control group. Importantly, higher concentrations of IFN-γ and IFN-γ-producing cells were also observed in splenocytes isolated from the experimental LASW1 mice, indicating that INF-γ secretion is important to the immune response to LASW1. The results indicate that LASW1 is a promising immune adjuvant in DNA vaccination against FMD when administrated orally.

China's transboundary waters: new paradigms for water and ecological security through applied ecology.

China is Asia's most important upstream riparian country, sharing 110 rivers and lakes with 18 downstream countries. Consequently, China's management of transboundary water resources must consider both environmental and geopolitical risks.The major threats to and conflicts over international rivers in China revolve around biotic homogenisation due to the installation of transport links, water allocation, water pollution, alteration of natural flow patterns and disruption of fisheries due to the installation of hydropower dams, and droughts and floods exacerbated by climate change. Because these problems have an international component, they fall under China's Peaceful Rise strategy, mandating that transboundary conflicts be resolved amicably as part of the overarching goal of increasing regional economic growth with as little conflict as possible.Science-backed policy is more likely to result in long term, mutually agreeable solutions; the results of applied ecological research have already resulted in a number of mitigation measures, including setting operational thresholds to reduce the downstream impact of dams, designating protected areas along key river stretches where dams cannot be installed (one dam in a critical location has been cancelled), and the installation of terrestrial protected-area networks.Synthesis and applications. Applied ecology will continue to play an important role in the diagnosis and resolution of environmental threats to China's transboundary waters. More importantly, applied ecology can inform the development of a transboundary environmental compensation mechanism and regional consultative mechanisms that support informed, cooperative decision-making for China and its riparian neighbours.

Immunogenicity of two FMDV nonameric peptides encapsulated in liposomes in mice and the protective efficacy in guinea pigs.

It has been predicted that nonameric peptides I (VP1(26-34), RRQHTDVSF), II (VP1(157-165), RTLPTSFNY) and III (VP1(45-53), KEQVNVLDL) from the VP1 capsid protein of the foot-and-mouth disease virus (FMDV) are T cell epitopes. To investigate whether these peptides have immunological activity, BALB/c mice were immunized with peptide I, II or III conjugated with immunostimulating complexes (ISCOMs). A cytotoxic T lymphocyte assay was used to evaluate the cytotoxic activity induced by peptides along with by measuring peptide-specific T-cell proliferation and CD8(+) T lymphocyte numbers in whole blood and interferon (IFN)-γ production in peripheral blood mononuclear cells induced by peptides. To further identify the protective efficacy of peptides, an FMDV challenge assay was done in guinea pigs. Peptides I and II stimulated significant increases in T-cell proliferation, CD8(+) T lymphocytes, and IFN-γ secretion and cytotoxic activity compared to controls. The FMDV challenge assay indicated peptides I and II can protect over 60% of animals from virus attack. The results demonstrate that peptides I and II encapsulated in liposomes should be CTL epitopes of FMDV and can protect animals from virus attack to some extent.

The influence of interpreters' professional background and experience on the interpretation of multimodality imaging of pulmonary lesions using 18F-3'-deoxy-fluorothymidine and 18F-fluorodeoxyglucose PET/CT.

OBJECTIVE: Based on the results of a recently accomplished multicenter clinical trial for the incremental value of a dual-tracer (18F-FDG and 18F-FLT), dual-modality (PET and CT) imaging in the differential diagnosis of pulmonary lesions, we investigate some issues that might affect the image interpretation and result reporting. METHODS: The images were read in two separate sessions. Firstly the images were read and reported by physician(s) of the imaging center on completion of each PET/CT scanning. By the end of MCCT, all images collected during the trial were re-read by a collective of readers in an isolated, blinded, and independent way. RESULTS: One hundred sixty two patients successfully passed the data verification and entered into the final analysis. The primary reporting result showed adding 18F-FDG image information did not change the clinical performance much in sensitivity, specifity and accuracy, but the ratio between SUVFLT and SUVFDG did help the differentiation efficacy among the three subgroups of patients. The collective reviewing result showed the diagnostic achievement varied with reading strategies. ANOVA indicated significant differences among (18)F-FDG, (18)F-FLT in SUV (F = 14.239, p = 0.004). CT had almost the same diagnostic performance as 18F-FLT. When the 18F-FDG, 18F-FLT and CT images read in pair, both diagnostic sensitivity and specificity improved. The best diagnostic figures were obtained in full-modality strategy, when dual-tracer PET worked in combination with CT. CONCLUSIONS: With certain experience and training both radiologists and nuclear physicians are qualified to read and to achieve the similar diagnostic accuracy in PET/CT study. Making full use of modality combination and selecting right criteria seems more practical than professional back ground and personal experience in the new hybrid imaging technology, at least when novel tracer or application is concerned.

Simple, rapid and reliable preparation of [¹¹C]-(+)-α-DTBZ of high quality for routine applications.

[¹¹C]-(+)-α-DTBZ has been used as a marker of dopaminergic terminal densities in human striatum and expressed in islet beta cells in the pancreas. We aimed to establish a fully automated and simple procedure for the synthesis of [¹¹C]-(+)-α-DTBZ for routine applications. [¹¹C]-(+)-α-DTBZ was synthesized from a 9-hydroxy precursor in acetone and potassium hydroxide with [¹¹C]-methyl triflate and was purified by solid phase extraction using a Vac tC-18 cartridge. Radiochemical yields based on [¹¹C]-methyl triflate (corrected for decay) were 82.3% ± 3.6%, with a specific radioactivity of 60 GBq/µmol. Time elapsed was less than 20 min from end of bombardment to release of the product for quality control.

Cadmium removal from wastewater by sponge iron sphere prepared by hydrogen reduction.

A new type of sponge iron sphere (NSIS) with 1-5 mm diameter, made of concentrated iron powder and possessed high activity and intension, was prepared by mini-pellet sintering integrated with H2 direct reduction. Static state experiment has been carried on to investigate the Cd(2+) removal efficiency from wastewater by the NSIS and to explore the Cd(2+) removal reaction kinetics. It was suggested that initial pH value and Cd(2+) original concentration had significant influence on Cd(2+) removal percentage. Cd(2+) removal percentage decreased significantly with the increasing of Cd(2+)original concentration whether the original pH value be adjusted to 3.0 or without adjustment. The results showed that the Cd(2+) removal process followed the first order reaction because the reaction order was from 0.803 to 0.996. The apparent reaction rate constant between Cd(2+) and NSIS was from 0.0025 to 0.1000 (mg·L(-1))(1-n)·min(-1). Compared with SIS reduced by charcoal reduction, NSIS deoxided by hydrogen possessed higher activity, and could remove the same quantity of Cd(2+) within a shorter period of time.

Cadmium removal from wastewater by sponge iron sphere prepared by charcoal direct reduction.

Sponge iron sphere (SIS), made of concentrated iron powder and possessed high activity and intension, was prepared through the process of palletizing, roasting and direct reduction by charcoal. The sponge iron sphere could remove most of Cd(2+) from wastewater. The results showed the Cd(2+) removal followed the first order reaction. Initial pH value played an important role in Cd(2+) removal. With original initial pH, Cd(2+) removal decreased to the minimum and then increased slightly with the rising of original concentration. The removal rate constant was -0.1263 and -0.0711 h(-1), respectively, under the Cd(2+) concentration of 50 and 200 mg/L. When the initial pH was adjusted to 3.0, the removal rate constant could increase to -9.896 and -4.351 h(-1), respectively. The removal percentage almost reached to 100% when Cd(2+) concentration was below 100 mg/L. While Cd(2+) concentration was above 100 mg/L, Cd(2+) removal percentage decreased slightly. In dynamic experiments, the column filled with sponge iron sphere exhibited favorable permeability. There was no sphere pulverization and conglutination between spheres. In contrast to the static state experiments, the Cd(2+) removal percentage in dynamic state experiment was lower, and the removal Cd(2+) quantity was 1.749 mg/g.

[Analyzing secondary structure of beta2 microglobulin in Escherichia coli with circular dichroism spectrum].

OBJECTIVE: In order to study the structure and function of beta2 microglobulin (beta2 m). METHODS: We sub-cloned the mature peptide of beta2 m into the p2X plasmid and transformed them to Escherichia coli TB1. The recombinant bacterium was induced to be expressed and the expressed fusion protein was detected by SDS-PAGE and western blot. After purifying and cleaving with Factor Xa, we separated the monomer protein beta2 m from MBP. Finally, we determined the secondary structure of the beta2 m protein by circular dichroism (CD) spectrum. RESULTS: MBP-beta2 m was 52.1 kDa, and the monomer protein beta2 m was 10.6 kDa. The alpha-helix, beta-sheet, turn, and random coil of the fusion protein showed 0, 45, 8 and 45 amino acids, respectively, detected by CD estimation. CONCLUSION: The beta2 m protein had correct secondary structure and could be used for further research of peptide binding in vitro.

Immune responses generated by Lactobacillus as a carrier in DNA immunization against foot-and-mouth disease virus.

To exploit Lactobacillus acidophilus as a carrier in DNA immunization against foot-and-mouth disease virus (FMDV), a recombinant eukaryotic expression plasmid (pRc/CMV2-VP1-Rep. 8014) harboring pRc/CMV2 vector, the FMDV VP1 gene, and a replication origin from Lactobacillus plantarum ATCC 8014 strain was constructed. To detect the VP1 protein, pRc/CMV2-VP1-Rep. 8014 was expressed in PK 15 cells and transfected into a L. acidophilus SW1 strain (L. acidophilus SFMD-1). To evaluate the immunization effect of L. acidophilus SFMD-1, anti-FMDV VP1 antibody, T-cell proliferation, antigen-specific delayed-type hypersensitivity (DTH), and tissue distribution were investigated using intramuscular, intraperitoneal, intranasal, and oral administration delivery routes. The results showed that L. acidophilus SFMD-1 was able to elicit a detectable antibody level on day 21. The VP1 antibody levels induced by L. acidophilus SFMD-1 and commercial inactivated FMDV vaccine rose rapidly to 0.84 and 0.70, respectively, by day 42, then sustained a high level by day 49. The route of administration had an impact on the magnitude of the systemic antigen-specific IgG responses, with intramuscularly applied L. acidophilus SFMD-1 generating the greatest FMDV VP1 antibody response, followed by intraperitoneal, intranasal, and oral administration delivery routes. Using the T-cell proliferation assay, the stimulation index of a group immunized with L. acidophilus SFMD-1 reached 2.78 versus 5.08 in a group immunized with pRc/CMV2-VP1-Rep. 8014 plasmid. Mice immunized with L. acidophilus SFMD-1 were able to induce T-cell-mediated antigen-specific DTH. In addition, the VP1 gene was detected in the muscle, kidney, spleen, and heart, but not in the liver. The results demonstrate clearly that Lactobacillus as a carrier is a promising approach of DNA vaccination, and is a potentially guard against FMDV.

Reconstruction of a swine SLA-I protein complex and determination of binding nonameric peptides derived from the foot-and-mouth disease virus.

No experimental system to date is available to identify viral T-cell epitopes in swine. In order to reconstruct the system for identification of short antigenic peptides, the swine SLA-2 gene was linked to the beta(2)m gene via (G4S)3, a linker encoding a 15-amino acid glycine-rich sequence (G4S)3, using splicing overlap extension-PCR (SOE-PCR). The maltose binding protein (MBP)-SLA-2-(G4S)3-beta(2)m fusion protein was expressed and purified in a pMAL-p2X/Escherichia coli TB1 system. The purified MBP-SLA-2-(G4S)3-beta(2)m protein was cleaved by factor Xa protease, and further purified by DEAE-Sepharose chromatography. The conformation of the SLA-2-(G4S)3-beta(2)m protein was determined by circular dichroism (CD) spectrum. In addition, the refolded SLA-2-(G4S)3-beta(2)m protein was used to bind three nonameric peptides derived from the foot-and-mouth disease virus (FMDV) O subtype VP1. The SLA-2-(G4S)3-beta(2)m-associated peptides were detected by mass spectrometry. The molecular weights and amino acid sequences of the peptides were confirmed by primary and secondary spectra, respectively. The results indicate that the SLA-2-(G4S)3-beta(2)m was 41.6kDa, and its alpha-helix, beta-sheet, turn, and random coil by CD estimation were 78 aa, 149 aa, 67 aa, and 93 aa, respectively. SLA-2-(G4S)3-beta(2)m protein was able to bind the nonameric peptides derived from the FMDV VP1 region: 26-34 (RRQHTDVSF) and 157-165 (RTLPTSFNY). The experimental system demonstrated that the reconstructed SLA-2-(G4S)3-beta(2)m protein complex can be used to identify nonameric peptides, including T-cell epitopes in swine.