1.Internal tension relieving technique assisted anterior cruciate ligament reconstruction to promote ligamentization of Achilles tendon grafts in small ear pigs in southern Yunnan province
Bohan XIONG ; Guoliang WANG ; Yang YU ; Wenqiang XUE ; Hong YU ; Jinrui LIU ; Zhaohui RUAN ; Yajuan LI ; Haolong LIU ; Kaiyan DONG ; Dan LONG ; Zhao CHEN
Chinese Journal of Tissue Engineering Research 2025;29(4):713-720
BACKGROUND:We have successfully established an animal model of small ear pig in southern Yunnan province with internal tension relieving technique combined with autologous Achilles tendon for anterior cruciate ligament reconstruction,and verified the stability and reliability of the model.However,whether internal tension relieving technique can promote the ligamentalization process of autologous Achilles tendon graft has not been studied. OBJECTIVE:To investigate the differences in the process of ligamentalization between conventional reconstruction and internal reduction reconstruction of the anterior cruciate ligament by gross view,histology and electron microscopy. METHODS:Thirty adult female small ear pigs in southern Yunnan province were selected.Anterior cruciate ligament reconstruction was performed on the left knee joint with the ipsilateral knee Achilles tendon(n=30 in the normal group),and anterior cruciate ligament reconstruction was performed on the right knee joint with the ipsilateral knee Achilles tendon combined with the internal relaxation and enhancement system(n=30 in the relaxation group).The autogenous right forelimb was used as the control group;the anterior cruciate ligament was exposed but not severed or surgically treated.At 12,24,and 48 weeks after surgery,10 animals were sacrificed,respectively.The left and right knee joint specimens were taken for gross morphological observation to evaluate the graft morphology.MAS score was used to evaluate the excellent and good rate of the ligament at each time point.Hematoxylin-eosin staining was used to evaluate the degree of ligament graft vascularization.Collagen fibers and nuclear morphology were observed,and nuclear morphology was scored.Ultrastructural remodeling was evaluated by scanning electron microscopy and transmission electron microscopy. RESULTS AND CONCLUSION:(1)The ligament healing shape of the relaxation group was better at various time points after surgery,and the excellent and good rate of MAS score was higher(P<0.05).Moreover,the relaxation group could obtain higher ligament vascularization score(P<0.05).(2)The arrangement of collagen bundles and fiber bundles in the two groups gradually tended to be orderly,and the transverse fiber connections between collagen gradually increased and thickened,suggesting that the strength and shape degree of the grafts were gradually improved,but the ligament remodeling in the relaxation group was always faster than that in the normal group at various time points after surgery.(3)The diameter,distribution density,and arrangement degree of collagen fibers in the relaxation group were better than those in the normal group at all time points,especially in the comparison of collagen fiber diameter between and within the relaxation group(P<0.05).
2.The Mechanisms of Quercetin in Improving Alzheimer’s Disease
Yu-Meng ZHANG ; Yu-Shan TIAN ; Jie LI ; Wen-Jun MU ; Chang-Feng YIN ; Huan CHEN ; Hong-Wei HOU
Progress in Biochemistry and Biophysics 2025;52(2):334-347
Alzheimer’s disease (AD) is a prevalent neurodegenerative condition characterized by progressive cognitive decline and memory loss. As the incidence of AD continues to rise annually, researchers have shown keen interest in the active components found in natural plants and their neuroprotective effects against AD. Quercetin, a flavonol widely present in fruits and vegetables, has multiple biological effects including anticancer, anti-inflammatory, and antioxidant. Oxidative stress plays a central role in the pathogenesis of AD, and the antioxidant properties of quercetin are essential for its neuroprotective function. Quercetin can modulate multiple signaling pathways related to AD, such as Nrf2-ARE, JNK, p38 MAPK, PON2, PI3K/Akt, and PKC, all of which are closely related to oxidative stress. Furthermore, quercetin is capable of inhibiting the aggregation of β‑amyloid protein (Aβ) and the phosphorylation of tau protein, as well as the activity of β‑secretase 1 and acetylcholinesterase, thus slowing down the progression of the disease.The review also provides insights into the pharmacokinetic properties of quercetin, including its absorption, metabolism, and excretion, as well as its bioavailability challenges and clinical applications. To improve the bioavailability and enhance the targeting of quercetin, the potential of quercetin nanomedicine delivery systems in the treatment of AD is also discussed. In summary, the multifaceted mechanisms of quercetin against AD provide a new perspective for drug development. However, translating these findings into clinical practice requires overcoming current limitations and ongoing research. In this way, its therapeutic potential in the treatment of AD can be fully utilized.
3.Enzyme-directed Immobilization Strategies for Biosensor Applications
Xing-Bao WANG ; Yao-Hong MA ; Yun-Long XUE ; Xiao-Zhen HUANG ; Yue SHAO ; Yi YU ; Bing-Lian WANG ; Qing-Ai LIU ; Li-He ZHANG ; Wei-Li GONG
Progress in Biochemistry and Biophysics 2025;52(2):374-394
Immobilized enzyme-based enzyme electrode biosensors, characterized by high sensitivity and efficiency, strong specificity, and compact size, demonstrate broad application prospects in life science research, disease diagnosis and monitoring, etc. Immobilization of enzyme is a critical step in determining the performance (stability, sensitivity, and reproducibility) of the biosensors. Random immobilization (physical adsorption, covalent cross-linking, etc.) can easily bring about problems, such as decreased enzyme activity and relatively unstable immobilization. Whereas, directional immobilization utilizing amino acid residue mutation, affinity peptide fusion, or nucleotide-specific binding to restrict the orientation of the enzymes provides new possibilities to solve the problems caused by random immobilization. In this paper, the principles, advantages and disadvantages and the application progress of enzyme electrode biosensors of different directional immobilization strategies for enzyme molecular sensing elements by specific amino acids (lysine, histidine, cysteine, unnatural amino acid) with functional groups introduced based on site-specific mutation, affinity peptides (gold binding peptides, carbon binding peptides, carbohydrate binding domains) fused through genetic engineering, and specific binding between nucleotides and target enzymes (proteins) were reviewed, and the application fields, advantages and limitations of various immobilized enzyme interface characterization techniques were discussed, hoping to provide theoretical and technical guidance for the creation of high-performance enzyme sensing elements and the manufacture of enzyme electrode sensors.
4.Translational Research of Electromagnetic Fields on Diseases Related With Bone Remodeling: Review and Prospects
Peng SHANG ; Jun-Yu LIU ; Sheng-Hang WANG ; Jian-Cheng YANG ; Zhe-Yuan ZHANG ; An-Lin LI ; Hao ZHANG ; Yu-Hong ZENG
Progress in Biochemistry and Biophysics 2025;52(2):439-455
Electromagnetic fields can regulate the fundamental biological processes involved in bone remodeling. As a non-invasive physical therapy, electromagnetic fields with specific parameters have demonstrated therapeutic effects on bone remodeling diseases, such as fractures and osteoporosis. Electromagnetic fields can be generated by the movement of charged particles or induced by varying currents. Based on whether the strength and direction of the electric field change over time, electromagnetic fields can be classified into static and time-varying fields. The treatment of bone remodeling diseases with static magnetic fields primarily focuses on fractures, often using magnetic splints to immobilize the fracture site while studying the effects of static magnetic fields on bone healing. However, there has been relatively little research on the prevention and treatment of osteoporosis using static magnetic fields. Pulsed electromagnetic fields, a type of time-varying field, have been widely used in clinical studies for treating fractures, osteoporosis, and non-union. However, current clinical applications are limited to low-frequency, and research on the relationship between frequency and biological effects remains insufficient. We believe that different types of electromagnetic fields acting on bone can induce various “secondary physical quantities”, such as magnetism, force, electricity, acoustics, and thermal energy, which can stimulate bone cells either individually or simultaneously. Bone cells possess specific electromagnetic properties, and in a static magnetic field, the presence of a magnetic field gradient can exert a certain magnetism on the bone tissue, leading to observable effects. In a time-varying magnetic field, the charged particles within the bone experience varying Lorentz forces, causing vibrations and generating acoustic effects. Additionally, as the frequency of the time-varying field increases, induced currents or potentials can be generated within the bone, leading to electrical effects. When the frequency and power exceed a certain threshold, electromagnetic energy can be converted into thermal energy, producing thermal effects. In summary, external electromagnetic fields with different characteristics can generate multiple physical quantities within biological tissues, such as magnetic, electric, mechanical, acoustic, and thermal effects. These physical quantities may also interact and couple with each other, stimulating the biological tissues in a combined or composite manner, thereby producing biological effects. This understanding is key to elucidating the electromagnetic mechanisms of how electromagnetic fields influence biological tissues. In the study of electromagnetic fields for bone remodeling diseases, attention should be paid to the biological effects of bone remodeling under different electromagnetic wave characteristics. This includes exploring innovative electromagnetic source technologies applicable to bone remodeling, identifying safe and effective electromagnetic field parameters, and combining basic research with technological invention to develop scientifically grounded, advanced key technologies for innovative electromagnetic treatment devices targeting bone remodeling diseases. In conclusion, electromagnetic fields and multiple physical factors have the potential to prevent and treat bone remodeling diseases, and have significant application prospects.
5.Effect of high-definition transcranial direct current stimulation combined with upper limb robot on upper limb dysfunction after ischemic stroke
Xiaojun WANG ; Hani WANG ; Hong YU ; Yuanmei LI ; Yuda ZHOU
Chinese Journal of Rehabilitation Theory and Practice 2025;31(2):218-224
ObjectiveTo investigate the effect of high-definition transcranial direct current stimulation (HD-tDCS) combined with upper limb robot on upper limb dysfunction in patients with ischemic stroke. MethodsFrom January, 2023 to March, 2024, 56 inpatients with upper limb dysfunction after ischemic stroke were selected from Zhejiang Rehabilitation Medical Center, and divided into control group (n = 28) and experimental group (n = 28) randomly. All the patients received comprehensive treatment and upper limb robot training, while the control group received sham HD-tDCS and the experimental group received HD-tDCS, for four weeks. They were assessed with Fugl-Meyer Assessment-Upper Extremities (FMA-UE), Wolf Motor Function Test (WMFT) and modified Barthel Index (MBI) before and after treatment. The cortical amplitude, cortical latency and central motor conduction time (CMCT) of transcranial magnetic stimulation motor-evoked potential (MEP) were recorded, and a correlation analysis was conducted. ResultsThe scores of FMA-UE, WMFT and MBI, and MEP cortical amplitude, cortical latency and CMCT improved in both groups after treatment (t > 3.177, P < 0.01), and they were better in the experimental group than in the control group (t > 3.610, P < 0.01). The scores of FMA-UE and WMFT negatively correlated with MEP cortical latency and CMCT, and positively correlated with MEP cortical amplitude (|r| > 0.448, P < 0.001). ConclusionHD-tDCS is effective on upper limb motor function and activities of daily living for patients with ischemic stroke, and can improve corticospinal motor conduction.
6.EGCG Promotes Aβ Clearance of Microglia Through Blockage of the HDAC6-PI3K/AKT/mTOR Signalling Axis Followed by Autophagy Activation
Yu LIN ; Kaiwen HUANG ; Honghai HONG ; Dan ZHU ; Yousheng MO ; Dongli LI ; Shuhuan FANG
Journal of Sun Yat-sen University(Medical Sciences) 2025;46(3):486-497
ObjectiveTo clarify whether epigallocatechin gallate (EGCG) is involved in the clearance of amyloid β-protein (Aβ) and autophagy induction by microglia, so as to explore the potential mechanisms of EGCG in the prevention and treatment of Alzheimer's disease (AD). MethodsSix-month-old APP/PS1 mice were randomly divided into model and EGCG groups, with some additional wild type (WT) mice as the control group, each group consisting of 15 mice. The EGCG group received continuous gavage administration[5 mg/(kg·d)] for 8 weeks, followed by the open field test and Y-maze to assess the learning and memory abilities of the mice. Thioflavin-S staining was used to evaluate the content and distribution of amyloid β-protein (Aβ)in the brain parenchyma of the mice, and immunofluorescence was employed to detect the expression levels of Aβ1-42, glial fibrillary acidic protein (GFAP), and ionized calcium-binding adapter molecule 1 (Iba1) in the hippocampal tissue of the mice. Additionally, N9 mouse microglial cells were induced with 20 µmol/L Aβ1-42, and the cell viability was measured after treatment with different concentrations of EGCG (5 µmol/L, 10 µmol/L, 20 µmol/L). Western blotting was used to detect the levels of Aβ1-42, low density lipoprotein receptor-related protein 1(LRP1), receptor for advanced glycation endproducts (RAGE), amyloid precursor protein (APP), insulin degrading enzyme (IDE), neprilysin (NEP), microtubule associated protein 1 hydrogen chain 3(LC3)-Ⅱ/LC3-Ⅰ, phosphatidylinositol 3-hydroxy kinase(PI3K), p-PI3K, protein kinase B (AKT), p-AKT, mammalian target of rapamycin (mTOR), p-mTOR, and histone deacetylase 6(HDAC6). Finally, through the co-culture of microglial cells and neuronal SH-SY5Y cells, cell viability and Caspase-3 levels were measured to verify the protective effect of EGCG-mediated Aβ clearance on neurons. ResultsEGCG increased the activity time and frequency of APP/PS1 mice in the central area of the open field (P<0.05), and enhanced the percentage of alternation in the Y-maze test (P<0.01); EGCG reduced Aβ deposition in the hippocampal tissue of APP/PS1 mice and increased the number of microglia; in vitro experiments showed that EGCG improved the survival rate of Aβ-induced N9 cells (P<0.01), upregulated RAGE activity (P<0.05), and promoted the internalization and phagocytosis of Aβ (P<0.01). ECGC activated microglial autophagy by downregulating the level of HDAC6 (P<0.05), inhibiting the phosphorylation of PI3K, AKT, mTOR (P<0.001), and increasing the LC3-Ⅱ/LC3-I ratio (P<0.001); EGCG improved the survival rate of SH-SY5Y cells (P<0.05) and reduced the activity of Caspase-3 (P<0.01) by clearing Aβ1-42 through microglia, and had a protective effect on neurons. ConclusionEGCG activates microglial autophagy to clear Aβ by targeting and inhibiting the HDAC6-PI3K/AKT/mTOR axis.
7.Danggui Shaoyaosan Combined with Yinchenhaotang Regulates Lipid Metabolism to Ameliorate Type 2 Diabetes Mellitus Complicated with Metabolic Dysfunction-associated Steatotic Liver Disease
Yilin XU ; Liu LI ; Junju ZOU ; Hong LI ; Rong YU
Chinese Journal of Experimental Traditional Medical Formulae 2025;31(15):38-47
ObjectiveTo explore the regulatory effect and mechanism of Danggui Shaoyaosan combined with Yinchenhaotang on lipid metabolism in the mouse model of type 2 diabetes mellitus (T2DM) complicated with metabolic dysfunction-associated steatotic liver disease (MASLD) based on network pharmacology and animal experiments. MethodsTwenty-four MKR transgenic diabetic mice were randomly allocated into 4 groups: Model, low-dose (12.6 g·kg-1) Chinese medicine (concentrated decoction of Danggui Shaoyaosan combined with Yinchenhaotang), high-dose (25.2 g·kg-1) Chinese medicine, and Western medicine (metformin, 0.065 g·kg-1). Six FVB mice were used as the normal group. All groups were treated for 6 consecutive weeks. The mice in the drug treatment groups were administrated with corresponding agents by gavage, and those in the normal group and model group received the same volume of distilled water. Fasting blood glucose, body weight, liver weight, glucose tolerance, liver function indicators, blood lipid levels, and pathological changes in the liver were evaluated for each group. Network pharmacology was employed to analyze the targets and pathways of Danggui Shaoyaosan combined with Yinchenhaotang in the treatment of T2DM complicated with MASLD. Molecular biological techniques were used to verify the enriched key targets. ResultsCompared with the model group, each treatment group showed reduced fasting blood glucose, body weight, aspartate aminotransferase (AST), alanine aminotransferase (ALT), and liver weight (P<0.01). The high-dose Chinese medicine group was superior to the low-dose group in reducing low-density lipoprotein (LDL), increasing high-density lipoprotein (HDL), and recovering glucose tolerance (AUC) and ALT (P<0.05), with the effect similar to that of the Western medicine group. Morphologically, Chinese medicine groups showed reduced lipid accumulation and alleviated pathological damage in the liver tissue, with the high-dose group demonstrating more significant changes. Network pharmacology results showed that Danggui Shaoyaosan combined with Yinchenhaotang may exert therapeutic effects through multiple targets such as fatty acid synthase (FAS), acetyl-CoA carboxylase (ACC), B-cell lymphoma-2 (Bcl-2), MYC oncogene (MYC), and interleukin-1β (IL-1β). Western blot showed that compared with the model group, the treatment groups demonstrated down-regulated protein levels of FAS and ACC (P<0.01) and up-regulated protein levels of peroxisome proliferator-activated receptor γ coactivator-1α (PGC-1α) and UCP1 (P<0.01). Compared with the low-dose Chinese medicine group, the high-dose Chinese medicine group exhibited down-regulated protein levels of FAS and ACC and up-regulated protein levels of PGC-1α and UCP1 (P<0.05). ConclusionDanggui Shaoyaosan combined with Yinchenhaotang has the effect of ameliorating T2DM complicated with MASLD and can improve the liver lipid metabolism by up-regulating the protein levels of Fas and ACC and down-regulating the protein levels of PGC-1α and UCP1.
8.Fast Object Perception in The Subcortical Pathway: a Commentary on Wang et al.’s Paper in Human Brain Mapping (2023)
Hao-Yun MA ; Yu-Yin WEI ; Li-Ping HU
Progress in Biochemistry and Biophysics 2025;52(7):1904-1908
The subcortical visual pathway is generally thought to be involved in dangerous information processing, such as fear processing and defensive behavior. A recent study, published in Human Brain Mapping, shows a new function of the subcortical pathway involved in the fast processing of non-emotional object perception. Rapid object processing is a critical function of visual system. Topological perception theory proposes that the initial perception of objects begins with the extraction of topological property (TP). However, the mechanism of rapid TP processing remains unclear. The researchers investigated the subcortical mechanism of TP processing with transcranial magnetic stimulation (TMS). They find that a subcortical magnocellular pathway is responsible for the early processing of TP, and this subcortical processing of TP accelerates object recognition. Based on their findings, we propose a novel training approach called subcortical magnocellular pathway training (SMPT), aimed at improving the efficiency of the subcortical M pathway to restore visual and attentional functions in disorders associated with subcortical pathway dysfunction.
9.Prediction of suitable habitats of Phlebotomus chinensis in Gansu Province based on the Biomod2 ensemble model
Dawei YU ; Yandong HOU ; Aiwei HE ; Yu FENG ; Guobing YANG ; Chengming YANG ; Hong LIANG ; Hailiang ZHANG ; Fan LI
Chinese Journal of Schistosomiasis Control 2025;37(3):276-283
Objective To investigate the suitable habitats of Phlebotomus chinensis in Gansu Province, so as provide insights into effective management of mountain-type zoonotic visceral leishmaniasis (MT-ZVL). Methods The geographical coordinates of locations where MT-ZVL cases were reported were retrieved in Gansu Province from 2015 to 2023, and data pertaining to 26 environmental variables were captured, including 19 climatic variables (annual mean temperature, mean diurnal range, isothermality, temperature seasonality, maximum temperature of the warmest month, minimum temperature of the coldest month, temperature annual range, mean temperature of the wettest quarter, mean temperature of the driest quarter, mean temperature of the warmest quarter, mean temperature of the coldest quarter, annual precipitation, precipitation of the wettest month, precipitation of the driest month, precipitation seasonality, precipitation of the wettest quarter, precipitation of the driest quarter, precipitation of the warmest quarter, and precipitation of the coldest quarter), five geographical variables (elevation, annual normalized difference vegetation index, vegetation type, landform type and land use type), and two population and economic variables (population distribution and gross domestic product). Twelve species distribution models were built using the biomod2 package in R project, including surface range envelope (SRE) model, generalized linear model (GLM), generalized additive model (GAM), multivariate adaptive regression splines (MARS) model, generalized boosted model (GBM), classification tree analysis (CTA) model, flexible discriminant analysis (FDA) model, maximum entropy (MaxEnt) model, optimized maximum entropy (MAXNET) model, artificial neural network (ANN) model, random forest (RF) model, and extreme gradient boosting (XGBOOST) model. The performance of 12 models was evaluated using the area under the receiver operating characteristic curve (AUC), true skill statistics (TSS), and Kappa coefficient, and single models with high performance was selected to build the optimal ensemble models. Factors affecting the survival of Ph. chinensis were identified based on climatic, geographical, population and economic variables. In addition, the suitable distribution areas of Ph. chinensis were predicted in Gansu Province under shared socioeconomic pathway 126 (SSP126), SSP370 and SSP585 scenarios based on climatic data during the period from 1991 to 2020, from 2041 to 2060 (2050s), and from 2081 to 2100 (2090s) . Results A total of 11 species distribution models were successfully built for prediction of potential distribution areas of Ph. chinensis in Gansu Province, and the RF model had the highest predictive accuracy (AUC = 0.998). The ensemble model built based on the RF model, XGBOOST model, GLM, and MARS model had an increased predictive accuracy (AUC = 0.999) relative to single models. Among the 26 environmental factors, precipitation of the wettest quarter (12.00%), maximum temperature of the warmest month (11.58%), and annual normalized difference vegetation index (11.29%) had the greatest contributions to suitable habitats distribution of Ph. sinensis. Under the climatic conditions from 1991 to 2020, the potential suitable habitat area for Ph. chinensis in Gansu Province was approximately 5.80 × 104 km2, of which the highly suitable area was 1.42 × 104 km2, and primarily concentrated in the southernmost region of Gansu Province. By the 2050s, the unsuitable and lowly suitable areas for Ph. chinensis in Gansu Province had decreased by varying degrees compared to that of 1991 to 2020 period, while the moderately and highly suitable areas exhibited expansion and migration. By the 2090s, under the SSP126 scenario, the suitable habitat area for Ph. chinensis increased significantly, and under the SSP585 scenario, the highly suitable areas transformed into extremely suitable areas, also showing substantial growth. Future global warming is conducive to the survival and reproduction of Ph. chinensis. From the 2050s to the 2090s, the highly suitable areas for Ph. chinensis in Gansu Province will be projected to expand northward. Under the SSP126 scenario, the suitable habitat area for Ph. chinensis in Gansu Province is expected to increase by 194.75% and 204.79% in the 2050s and 2090s, respectively, compared to that of the 1991 to 2020 period. Under the SSP370 scenario, the moderately and highly suitable areas will be projected to increase by 164.40% and 209.03% in the 2050s and 2090s, respectively, while under the SSP585 scenario, they are expected to increase by 195.98% and 211.66%, respectively. Conclusions The distribution of potential suitable habitats of Ph. sinensis gradually shifts with climatic changes. Intensified surveillance and management of Ph. sinensis is recommended in central and eastern parts of Gansu Province to support early warning of MT-ZVL.
10.Preliminary study on the biological characteristics of heat shock cognate protein 20 of Schistosoma japonicum
Xingang YU ; Kaijian YUAN ; Yilong LI ; Xuanru MU ; Hui XU ; Qiaoyu LI ; Wenjing ZENG ; Zhiqiang FU ; Yang HONG
Chinese Journal of Schistosomiasis Control 2025;37(3):294-303
Objective To clone and express the heat shock cognate protein 20 (SjHsc20) of Schistosoma japonicum, and to preliminarily investigate its biological characteristics. Methods The target fragment of the SjHsc20 gene was amplified using PCR assay and cloned into the pET-28a(+) expression plasmid to generate the recombinant expression vector pET-28a(+)-SjH-sc20, which was then transformed into Escherichia coli BL21 (DE3) competent cells. The recombinant SjHsc20 (rSjHsc20) protein was induced with isopropyl β-D-thiogalactopyranoside (IPTG) and purified, and the expression of the rSjHsc20 protein was checked with sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). The immunogenicity of the rSjHsc20 protein was detected using Western blotting, and the transcriptional levels of SjHsc20 were quantified in S. japonicum worms at different developmental stages and in male and female adult worms using real-time quantitative PCR (RT-qPCR) assay. Thirty female BALB/c mice at ages 6 to 8 weeks were divided into three groups, including the rSjHsc20 immunization group, the PBS control group, and the ISA 206 adjuvant group, of 10 mice in each group. Mice in the rSjHsc20 immunization group were subcutaneously immunized with 20 μg rSjHsc20 on days 1, 15 and 31, and animals in the PBS control group were subcutaneously injected with the same volume of PBS on days 1, 15 and 31, while mice in the ISA 206 adjuvant group were subcutaneously immunized with the same volume of ISA 206 adjuvant on days 1, 15 and 31, respectively. All mice in each group were infected with (40 ± 2) S. japonicum cercariae via the abdomen 14 day following the last immunization. Levels of serum specific IgG and its subtypes IgG1 and IgG2 antibodies against rSjHsc20, and the serum titers of anti-rSjHsc20 antibody were detected in mice using indirect enzyme-linked immunosorbent assay (ELISA). All mice were sacrifice 42 days post-infection, and S. japonicum worms were collected from the hepatic portal vein and counted. The eggs per gram (EPG), worm burden reductions and egg burden reductions were estimated to evaluate the protective efficacy of the rSjHsc20 protein. Results The SjHsc20 gene had an open reading frame (ORF) with 756 bp in length and encoded 252 amino acids, and the rSjHsc20 protein had a relative molecular mass of approximately 29 kDa. The rSjHsc20 protein was recognized by the serum of mice infected with S. japonicum and the serum of mice immunized with the rSjHsc20 protein, indicating that rSjHsc20 had a good immunogenicity. There was a significant difference in the transcriptional levels of the SjHsc20 gene among the 7-day (1.001 4 ± 0.065 7), 12-day (2.268 3 ± 0.129 2), 21-day (1.378 5 ± 0.160 4), 28-day (1.196 4 ± 0.244 0), 35-day (1.646 3 ± 0.226 1), 42-day worms of S. japonicum (1.758 0 ± 0.611 1) (F = 38.45, P < 0.000 1), and the transcriptional level of the SjHsc20 gene was higher in the 12-day worms than in worms at other developmental stages (all P values < 0.000 1). The serum levels of anti-rSjHsc20 IgG antibody were 0.106 6 ± 0.010 7, 0.108 3 ± 0.010 4, and 0.553 2 ± 0.069 1 in the PBS control group, ISA 206 adjuvant group, and rSjHsc20 immunization group following the last immunization, respectively, and the serum levels of IgG1 antibody were 0.137 3 ± 0.054 0, 0.181 1 ± 0.096 8, and 1.765 8 ± 0.221 1, while the levels of IgG2a antibody were 0.280 3 ± 0.197 6, 0.274 0 ± 0.146 3, and 1.560 4 ± 0.106 0, respectively. There were significant differences in the serum levels of anti-rSjHsc20 IgG (F = 397.70, P < 0.000 1), IgG1 (F = 401.00, P < 0.000 1) and IgG2a antibodies (F = 229.70, P < 0.000 1) among the three groups, and the serum levels of anti-rSjHsc20 IgG, IgG1 and IgG2a antibodies were higher in the rSjHsc20 immunization group than in the PBS control group and the ISA 206 adjuvant group (all P values < 0.000 1). There was a significant difference in the IgG1/IgG2a ratio among the rSjHsc20 immunization group (1.177 2 ± 0.143 6), the PBS control group (0.428 4 ± 0.199 8) and the ISA 206 adjuvant group (0.559 9 ± 0.181 1) (F = 43.97, P < 0.000 1), and the IgG1/IgG2a ratio was > 1 in the rSjHsc20 immunization group, which was higher than in the PBS control group and the ISA 206 adjuvant group (both P values < 0.000 1). The titers of serum anti-rSjHsc20 antibody were all above 1∶16 384 in the rSjHsc20 immunization group following immunizations on days 1, 15 and 31, indicating that the rSjHsc20 protein had a strong immunogenicity. The mean worm burdens were (16.60±5.75), (15.80±5.58) worms per mouse and (14.40±5.75) worms per mouse in the PBS control group, the ISA 206 adjuvant group and the rSjHsc20 immunization group 42 days post-infection with S. japonicum cercariae (F = 0.50, P > 0.05), and the EPG were 68 370 ± 22 690, 67 972 ± 19 502, and 41 075 ± 13 251 in the PBS control group, the ISA 206 adjuvant group and the rSjHsc20 immunization group (F = 4.55, P < 0.05), with lower EPG in the PBS control group and the ISA 206 adjuvant group than in the rSjHsc20 immunization group (both P values < 0.05). Immunization with the rSjHsc20 protein resulted in a worm burden reduction of 13.25% and an egg burden reduction of 39.92% relative to the PBS control group. Conclusions SjHsc20 is successfully cloned and expressed, and the rSjHsc20 protein induces partial immunoprotective effects in mice, which provides a basis for deciphering the biological functions of SjHsc20 and assessing the potential of SjH-sc20 as a vaccine candidate.

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