1.Prokaryotic expression of Echinococcus granulosus Polo-like kinase 2 and immunoprotective efficacy of its recombinant protein
Xue WANG ; Mingzhi YAN ; Wenjing QI ; Chuanchuan WU ; Guowu ZHANG ; An GENG ; Mengxiao TIAN ; Jun LI ; Wenbao ZHANG
Chinese Journal of Schistosomiasis Control 2026;38(2):184-193
Objective To prepare the recombinant Echinococcus granulosus Polo-like kinase 2 (rEgPLK2) protein and evaluate its immunoprotective efficacy against cystic echinococcosis, so as to provide insights into research and development of novel vaccines against echinococcosis. Methods The Polo-like kinase (PLK) protein sequences were retrieved from 12 species in the NCBI protein database, including E. granulosus and E. multilocularis. Multiple sequence alignment was performed using the Clustal Omega program, and structural visualization and homology analysis were conducted using the ESPript 3.2 program. The recombinant plasmid pET-30a-EgPLK2 was transformed into BL21(DE3) competent cells. Protein expression was induced with isopropyl-β-D-thiogalactoside (IPTG), and sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) was performed to characterize the expression and molecular weight of the rEgPLK2 protein. The purified rEgPLK2 protein was thoroughly emulsified with Freund’s complete adjuvant at a 1 : 1 volume ratio. Two New Zealand white rabbits were immunized with multipoint subcutaneous injection on the back at a dose of 300 μg per rabbit for primary immunization. For booster immunizations, the protein was emulsified with Freund’s incomplete adjuvant at a 1 : 1 volume ratio and administered on days 14, 28, and 42 after the primary immunization at a dose of 150 μg per rabbit. Serum was sampled from the rabbit ear vein on day 7 after the final immunization to yield anti-rEgPLK2 polyclonal antibodies. Antibody titer was determined by indirect enzyme-linked immunosorbent assay (ELISA), and antibody specificity was verified by Western blotting. The tissue localization of the EgPLK2 protein was detected in E. granulosus protoscoleces and adult worms using immunofluorescence assay (IFA). Eighteen 6- to 8-week-old female SPF-grade BALB/c mice were randomly divided into three groups, including the blank control group, rEgPLK2-ISA immunization group, and PBS-ISA adjuvant control group, of 6 mice each group. Mice in the rEgPLK2-ISA immunization group and PBSISA group received three primary immunizations via intramuscular injection, and animals in the rEgPLK2-ISA immunization group was inoculated with immunogens prepared by emulsifying rEgPLK2 protein with ISA 201 adjuvant at a 1 : 1 volume ratio (6 μg per mouse), while mice in the PBS-ISA adjuvant control group received an equal volume of PBS emulsified with ISA adjuvant at a 1 : 1 volume ratio. A fourth booster immunization was administered via intraperitoneal injection. Mice in the rEgPLK2-ISA immunization group received a booster immunization with 8 μg of rEgPLK2 protein per mouse, and animals in the PBS-ISA group received an equal volume of PBS, with immunizations given at 2-week intervals. Mice in the blank control group were given no treatment, and housed under standard conditions. Tail vein blood was collected from all mice 7 days after the final immunization, and levels of specific anti-rEgPLK2 IgG antibody and its subclasses (IgG1, IgG2a, IgG2b, IgG3) were measured by indirect ELISA. E. granulosus infection was modelled in mice through injection with 1 000 E. granulosus protoscoleces via intrahepatic portal vein in the rEgPLK2-ISA immunization group and PBS-ISA adjuvant control group 2 weeks after the last immunization. All mice were sacrificed and dissected. The number of cysts was counted in mouse livers, and the cyst reduction rate was calculated. Liver tissues were processed for paraffin sectioning and stained with hematoxylin and eosin (HE), and histopathological changes were examined under a light microscope. Results Sequence analysis revealed that EgPLK2 shared a high amino acid sequence homology with E. multilocularis PLK2 (EmPLK2) and contained the typical domains of the Polo-like kinase family, including the serine/threonine protein kinase catalytic domain (STKc) and Polo-box. The IPTG-induced rEgPLK2 protein was mainly expressed in the form of inclusion bodies, and the purified rEgPLK2 protein showed a relative molecular mass of approximately 70 kDa. The prepared rabbit anti-rEgPLK2 polyclonal antibody had a titer of 1 : 256 000, and Western blotting assay showed that this anti-body specifically recognized the rEgPLK2 protein with a relative molecular mass of approximately 70 kDa. Immunofluorescence assay showed that the EgPLK2 protein was localized in the excretory bladder and rostellum of E. granulosus protoscoleces, as well as the tegument, suckers, and inter-proglottid junctions of adult worms. Immunoprotective assay showed that the serum levels of specific anti-rEgPLK2 IgG, IgG1, IgG2a, and IgG2b antibodies were 2.92 ± 0.49, 0.33 ± 0.10, 0.31 (0.36), and 3.12 (1.73) in mice in the rEgPLK2-ISA immunization group, which were all significantly higher than those in the PBS-ISA adjuvant control group (0.14 ± 0.04, 0.07 ± 0.01, 0.12 ± 0.04, and 0.11 ± 0.04, respectively) (t = 19.28 and 8.46, Z = 3.75 and 4.15; all P values < 0.001); however, there was no significant difference in the serum anti-IgG3 antibody level between the rEgPLK2-ISA immunization group and the PBS-ISA adjuvant control group [0.07 (0.01) vs. 0.073 (0.07); Z = 0.69, P > 0.05)]. In the mouse model of E. granulosus infections, the area of hepatic lesions was reduced and the inflammatory infiltration was alleviated in the rEgPLK2-ISA immunization group than in the PBS-ISA adjuvant control group, and the number of hepatic cysts was higher in the PBS-ISA adjuvant control group than in the rEgPLK2-ISA immunization group [8.00 (2.00) vs. 1.00 (0.75); Z = −2.93, P < 0.01], with a cyst reduction rate of 80.40%. Indirect ELISA assay measured higher serum levels of specific anti-rEgPLK2 IgG (3.28 ± 0.48 vs. 0.11 ± 0.04; t = 15.86, P < 0.01), IgG1 (0.29 ± 0.02 vs. 0.09 ± 0.01; t = 15.67, P < 0.01), IgG2a [3.71 (1.09) vs. 0.08 (0.03); Z = 2.88, P < 0.01], and IgG2b antibodies [3.34 (1.01) vs. 0.08 (0.03); Z = 2.88, P < 0.01] in the rEgPLK2-ISA immunization group than in the PBS-ISA adjuvant control group, and there was no significant difference in the serum level of the specific anti-rEgPLK2 IgG3 antibody between the rEgPLK2-ISA immunization group and the PBS-ISA adjuvant control group (0.07 ± 0.01 vs. 0.07 ± 0.01; t = 1.29, P > 0.05). Conclusions The prokaryotic expression system has been successfully constructed for the EgPLK2 gene and the anti-rEgPLK2 polyclonal antibody has been obtained. The rEgPLK2 protein exhibits a high immunogenicity, and is effective to protect against E. granulosus infection, and inhibits cyst development, which is a promising candidate vaccine target against cystic echinococcosis.
2.Comparison of short-term outcomes and 5-year overall survival between robotic and laparoscopic gastrectomy for gastric cancer
Li ZHANG ; Mingzhi CAI ; Bin LI ; Gang MA ; Xuejing ZHENG ; Ye TIAN ; Xuejun WANG ; Yong LIU ; Han LIANG
Chinese Journal of General Surgery 2025;40(8):601-606
Objective:To compare the short-term clinical outcomes of robotic gastrectomy (RG) and laparoscopic gastrectomy (LG) in treating gastric cancer, as well as the overall 5-year's survival rate.Methods:In this retrospective cohort study, 874 patients undergoing minimally invasive gastrectomy were recruited from Jan 2016 to Jan 2020 (LG: n=719; RG: n=155). A one-to-one propensity score matching analysis was applied to minimize the selection bias due to confounding factors, yielding 150 patients in each of the RG and LG groups. After matching, the short-term outcomes and 5-year overall survival were compared in the two groups. Results:The propensity score matching cohort analysis showed a similar 5-year overall survival between RG and LG groups ( P=0.235). Concerning the short-term outcomes, the RG compared to LG resulted in lower blood loss ( P=0.011), lower postoperative complications ( P=0.001), less postoperative pain ( P=0.014), earlier initiation of soft diet ( P=0.010), shorter hospital stay ( P=0.011), but higher hospitalization expenses ( P=0.004). Conclusions:RG had a similar overall survival outcome compared to LG while offering better safety and efficacy in terms of less blood loss, lower surgery complications, faster recovery, and less postoperative pain. Higher hospital expenses were the main disadvantage of RG that could limit its application.
3.Artificial intelligence-assisted compressed sensing cardiac MR cine imaging for assessing biventricular function and left ventricular myocardial strain
Mingzhi LI ; Xiqing WU ; Qin LI ; Wei CAO ; Yanni YU
Chinese Journal of Interventional Imaging and Therapy 2025;22(7):481-485
Objective To explore the value of artificial intelligence-assisted compressed sensing(ACS)-MR cine imaging(Cine)for assessing biventricular function and left ventricular myocardial strain compared with conventional cardiac Cine and united compressed sensing(uCS)-Cine.Methods A total of 30 subjects who underwent conventional Cine,uCS-Cine and ACS-Cine were prospectively enrolled.Based on a 5-point scale,subjective scoring of image quality was performed and compared among 3 sequences.Biventricular function parameters and myocardial strain parameters of the left ventricle,including left ventricular end-diastolic volume(LVEDV),left ventricular end-systolic volume(LVESV),left ventricular ejection fraction(LVEF),left ventricular end-diastolic mass(LVEDM),right ventricular end-diastolic volume(RVEDV),right ventricular end-systolic volume(RVESV),right ventricular ejection fraction(RVEF),left ventricular global radial strain(LVGRS),left ventricular global circumferential strain(LVGCS)and left ventricular global longitudinal strain(LVGLS)were measured and compared among sequences.Results The subjective image quality scores of all 3 sequences were≥3,of ACS-Cine and conventional Cine were not significantly different(adjusted P=0.306)but both slightly higher than that of uCS-Cine(both adjusted P<0.05).LVEDV,LVEF and LVEDM based on ACS-Cine and uCS-Cine were not significantly different(all adjusted P>0.05),but all lower than those of conventional Cine(all adjusted P<0.05).No significant difference of LVESV was found between each two sequences(all adjusted P>0.05).RVEDV based on ACS-Cine was lower than that based on conventional Cine,RVESV based on ACS-Cine was higher than that based on uCS-Cine,and RVEF based on ACS-Cine was lower than that based on uCS-Cine and conventional Cine(all adjusted P<0.05),while no significant difference of right ventricular functional parameters was observed between uCS-Cine and conventional Cine(all adjusted P>0.05).Both ACS-Cine and uCS-Cine had lower LVGRS and LVGCS than conventional Cine(all adjusted P<0.05),with no significant difference was found between uCS-Cine and ACS-Cine(both adjusted P>0.05).No significant difference of LVGLS was observed among 3 sequences(P>0.05).Conclusion ACS-Cine could be used as appropriate supplement to conventional Cine for clinical assessment of biventricular function and left ventricular myocardial strain.
4.Clinical application of an artificial intelligence system in predicting benign or malignant pulmonary nodules and pathological subtypes
Zhuowen YANG ; Zhizhong ZHENG ; Bin LI ; Yiming HUI ; Mingzhi LIN ; Jiying DANG ; Suiyang LI ; Chunjiao ZHANG ; Long YANG ; Liang SI ; Tieniu SONG ; Yuqi MENG
Chinese Journal of Clinical Thoracic and Cardiovascular Surgery 2025;32(08):1086-1095
Objective To evaluate the predictive ability and clinical application value of artificial intelligence (AI) systems in the benign and malignant differentiation and pathological type of pulmonary nodules, and to summarize clinical application experience. Methods A retrospective analysis was conducted on the clinical data of patients with pulmonary nodules admitted to the Department of Thoracic Surgery, Second Hospital of Lanzhou University, from February 2016 to February 2025. Firstly, pulmonary nodules were divided into benign and non-benign groups, and the discriminative abilities of AI systems and clinicians were compared. Subsequently, lung nodules reported as precursor glandular lesions (PGL), microinvasive adenocarcinoma (MIA), and invasive adenocarcinoma (IAC) in postoperative pathological results were analyzed, comparing the efficacy of AI systems and clinicians in predicting the pathological type of pulmonary nodules. Results In the analysis of benign/non-benign pulmonary nodules, clinical data from a total of 638 patients with pulmonary nodules were included, of which there were 257 males (10 patients and 1 patient of double and triple primary lesions, respectively) and 381 females (18 patients and 1 patient of double and triple primary lesions, respectively), with a median age of 55.0 (47.0, 61.0) years. Different lesions in the same patient were analyzed as independent samples. Univariate analysis of the two groups of variables showed that, except for nodule location, the differences in the remaining variables were statistically significant (P<0.05). Multivariate logistic regression analysis showed that age, nodule type (subsolid pulmonary nodule), average density, spicule sign, and vascular convergence sign were independent influencing factors for non-benign pulmonary nodules, among which age, nodule type (subsolid pulmonary nodule), spicule sign, and vascular convergence sign were positively correlated with non-benign pulmonary nodules, while average density was negatively correlated with the occurrence of non-benign pulmonary nodules. The area under the receiver operating characteristic curve (AUC) of the malignancy risk value given by the AI system in predicting non-benign pulmonary nodules was 0.811, slightly lower than the 0.898 predicted by clinicians. In the PGL/MIA/IAC analysis, clinical data from a total of 411 patients with pulmonary nodules were included, of which there were 149 males (8 patients of double primary lesions) and 262 females (17 patients of double primary lesions), with a median age of 56.0 (50.0, 61.0) years. Different lesions in the same patient were analyzed as independent samples. Univariate analysis results showed that, except for gender, nodule location, and vascular convergence sign, the differences in the remaining variables among the three groups of PGL, MIA, and IAC patients were statistically significant (P<0.05). Multinomial multivariate logistic regression analysis showed that the differences between the parameters in the PGL group and the MIA group were not statistically significant (P>0.05), and the maximum diameter and average density of the nodules were statistically different between the PGL and IAC groups (P<0.05), and were positively correlated with the occurrence of IAC as independent risk factors. The average AUC value, accuracy, recall rate, and F1 score of the AI system in predicting lung nodule pathological type were 0.807, 74.3%, 73.2%, and 68.5%, respectively, all better than the clinical physicians’ prediction of lung nodule pathological type indicators (0.782, 70.9%, 66.2%, and 63.7% respectively). The AUC value of the AI system in predicting IAC was 0.853, and the sensitivity, specificity, and optimal cutoff value were 0.643, 0.943, and 50.0%, respectively. Conclusion This AI system has demonstrated high clinical value in predicting the benign and malignant nature and pathological type of lung nodules, especially in predicting lung nodule pathological type, its ability has surpassed that of clinical physicians. With the optimization of algorithms and the adequate integration of multimodal data, it can better assist clinical physicians in formulating individualized diagnostic and treatment plans for patients with lung nodules.
5.Effects of psychological stress on inflammatory bowel disease via affecting the microbiota-gut-brain axis.
Yuhan CHEN ; Xiaofen CHEN ; Suqin LIN ; Shengjun HUANG ; Lijuan LI ; Mingzhi HONG ; Jianzhou LI ; Lili MA ; Juan MA
Chinese Medical Journal 2025;138(6):664-677
Inflammatory bowel disease (IBD) is an idiopathic intestinal inflammatory condition with chronic and relapsing manifestations and is characterized by a disturbance in the interplay between the intestinal microbiota, the gut, and the brain. The microbiota-gut-brain axis involves interactions among the nervous system, the neuroendocrine system, the gut microbiota, and the host immune system. Increasing published data indicate that psychological stress exacerbates the severity of IBD due to its negative effects on the microbiota-gut-brain axis, including alterations in the stress response of the hypothalamic-pituitary-adrenal (HPA) axis, the balance between the sympathetic nervous system and vagus nerves, the homeostasis of the intestinal flora and metabolites, and normal intestinal immunity and permeability. Although the current evidence is insufficient, psychotropic agents, psychotherapies, and interventions targeting the microbiota-gut-brain axis show the potential to improve symptoms and quality of life in IBD patients. Therefore, further studies that translate recent findings into therapeutic approaches that improve both physical and psychological well-being are needed.
Humans
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Inflammatory Bowel Diseases/metabolism*
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Stress, Psychological/microbiology*
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Gastrointestinal Microbiome/physiology*
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Brain/metabolism*
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Hypothalamo-Hypophyseal System
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Pituitary-Adrenal System
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Animals
6.Clinical research design and challenges of multi-conjugate vaccine and polyvalent vaccine
Hongyan LIU ; Weiwei HAN ; Mingzhi GAN ; Fengcai ZHU ; Jingxin LI
Chinese Journal of Epidemiology 2025;46(7):1304-1310
Multi-conjugate vaccine and polyvalent vaccine can reduce the number of vaccinations, improve vaccination efficiency, and provide wider protection against diseases, and can not only brings convenience to recipients but also reduce healthcare costs, making it a key focus in modern vaccine development. However, even if the components of the vaccine are derived from already approved monovalent vaccines, it must still be considered as a new vaccine and undergo randomized controlled clinical trials to evaluate their safety and efficacy in humans. Due to the inclusion of multiple antigens, clinical evaluation must consider the potential interactions between or among the components, as well as the impacts of adjuvants, preservatives, and other ingredients on the vaccines' safety and efficacy. These factors introduce certain specific challenges in the clinical evaluation of multi-conjugate vaccine and polyvalent vaccine. This article summarizes the key elements and methods of clinical study design for multi-conjugate vaccine and polyvalent vaccine in terms of safety, immunogenicity, and protective efficacy, and discuss the problems and challenges exisitng in vaccine clinical evaluation to provide reference for the standardization of clinical study design of multi-conjugate vaccine and polyvalent vaccine.
7.Multivariate analysis of cognitive dysfunction in maintenance hemodialysis patients
Yafei BAI ; Ruman CHEN ; Mingzhi XU ; Na AN ; Chunli WANG ; Xin ZENG ; Jifeng LI ; Qian WEI ; Hong LI
Chinese Journal of Nephrology 2025;41(1):49-53
This study was a single-center cross-sectional investigation aimed at identifying risk factors for cognitive dysfunction in patients undergoing maintenance hemodialysis (MHD), with the goal of providing a basis for improving patient prognosis. Patients receiving MHD in the Blood Purification Center of Hainan Provincial People's Hospital from June 1 to June 30, 2023, were enrolled. Cognitive function was assessed using the Mini-Mental State Examination (MMSE), and potential risk factors for cognitive impairment were analyzed by using Logistic regression. A total of 278 patients were included, 69 patients (24.8%) of whom had cognitive impairment. Multivariate Logistic regression analysis indicated that the history of cerebrovascular disease ( OR=3.109, 95% CI 1.310-7.378, P=0.010), old age ( OR=1.077, 95% CI 1.040-1.115, P<0.001), low dialysis frequency ( OR=0.270, 95% CI 0.120-0.606, P=0.001), low academic qualification (using college/university as the control group: primary school group OR=26.960, 95% CI 7.519-96.673, P<0.001; Junior high school/technical secondary school group OR=4.264, 95% CI 1.330-13.650, P=0.015; High school group OR=9.554, 95% CI 2.861-31.904, P<0.001), high β2-microglobulin ( OR=1.609, 95% CI 1.044-2.480, P=0.031) and high C-reactive protein/albumin ( OR=2.672, 95% CI 1.226-5.826, P=0.013) were independent risk factors for cognitive impairment in MHD patients.
8.Cytological origin of intimal hyperplasia in autologous arteriovenous fistula
Yafei BAI ; Ruman CHEN ; Mingjiao PAN ; Mingzhi XU ; Na AN ; Chunli WANG ; Hong LI
Chinese Journal of Nephrology 2025;41(5):389-393
Autogenous arteriovenous fistula (AVF), compared to other vascular access routes, offers the advantages of stable blood flow, fewer complications, and a longer service life, making it the primary type of vascular access and the first choice for hemodialysis patients. The failure rate of AVF maturation is as high as 20% to 60%, primarily due to intimal hyperplasia following AVF surgery. Currently, the origin, function, and differentiation status of neointimal cells are not well understood, and most knowledge about neointimal cells was inferred from arterial neointima in non-AVF systems. Understanding the source of neointimal cells in AVF is crucial for experimental design and effectively providing strategies to reduce intimal hyperplasia. This article reviews the situation of venous intimal hyperplasia in patients with stage 5 chronic kidney disease, the relationship between changes in venous vessel wall and neointimal cells after AVF surgery, and the effects of outer membrane fibroblasts, local smooth muscle cells, and circulating bone marrow progenitor cells on AVF intimal hyperplasia. It is hoped that this will provide a reference for the treatment of intimal hyperplasia and experimental research.
9.Clinical study on the combination of Jianpi Bushen Jiedu Prescription with 5-fluorouracil-based chemotherapy and targeted therapy for the treatment of advanced colorectal cancer
Yuying HUANG ; Juan CHEN ; Tao GONG ; Miao MA ; Yanhua ZHAO ; Zihan LIN ; Haina DU ; Xiaokang TIAN ; Mingzhi FANG ; Min LI
International Journal of Traditional Chinese Medicine 2025;47(8):1059-1065
Objective:To observe the clinical efficacy and safety of Jianpi Bushen Jiedu Prescription combined with 5-fluorouracil (5-FU)-based chemotherapy and targeted therapy for the treatment of advanced colorectal cancer patients with liver and kidney yin deficiency combined with spleen deficiency pattern.Methods:A randomized controlled trial was conducted. A total of 72 hospitalized patients with advanced colorectal cancer treated at the Department of Oncology, Nanjing Hospital of Traditional Chinese Medicine Affiliated to Nanjing University of Chinese Medicine from October 2022 to January 2024 were enrolled as study subjects. Using a random number table method, they were allocated into two groups, with 36 patients in each group. The control group received the mFOLFOX6/FOLFIRI combined with bevacizumab regimen, while the treatment group was administered additional oral Jianpi Bushen Jiedu Prescription on the basis of the control group. Two weeks was a cycle in both groups, with a total of 6 cycles of treatment. Serum levels of carcinoembryonic antigen (CEA), carbohydrate antigen 199 (CA199), and carbohydrate antigen 724 (CA724) were detected using electrochemiluminescence; the Karnofsky Performance Status (KPS) scale was utilized to evaluate patients' functional status; vital signs were continuously monitored, and adverse reactions were recorded. The short-term efficacy and TCM syndrome efficacy of patients were evaluated.Results:The treatment group demonstrated higher objective response rate (ORR) [31.25% (10/32) vs. 21.88% (7/32), χ2=0.72] and disease control rate (DCR) [84.38% (27/32) vs. 71.88% (23/32), χ2=1.46] compared to the control group, without statistical significance ( P>0.05). Post-treatment levels of CEA [4.09 (3.31,8.57) μg/L vs. 10.07 (4.55,22.35) μg/L, Z=-2.10] and CA72-4 [4.54 (2.04,10.99) mU/L vs. 9.48 (4.34,18.95) mU/L, Z=-2.52] in the treatment group were significantly lower than those in the control group ( P<0.05). The total effective rate of TCM syndrome was significantly higher in the treatment group [78.13% (25/32)] compared with the control group [50.00% (16/32)], with statistical significance ( χ2=5.50, P=0.019). Post-treatment KPS scores in the treatment group [80.0 (80.0, 80.0) vs. 70.0 (62.5, 80.0), Z=-2.76] were significantly higher compared with the control group ( P<0.01). During the treatment period, the treatment group showed statistical significance compared with the control group in the incidence of hemoglobin decrease ( χ2=4.66), leukopenia decrease ( χ2=4.27), and peripheral neuropathy ( χ2=3.93), with statistical significance ( P<0.05). Conclusion:The addition of Jianpi Bushen Jiedu Prescription to 5-FU-based chemotherapy combined with targeted therapy demonstrates significant clinical benefits in advanced colorectal cancer patients, including reducing tumor marker levels, alleviating clinical symptoms, improving quality of life, and mitigating treatment-related toxicities, with a good safety.
10.Prokaryotic expression, purification and immunogenicity of SARS-CoV-2 omicron variant nucleocapsid protein.
Zewen TU ; Quansheng WANG ; Shiguo LIU ; Haosen LIU ; Chunyan ZENG ; Juanjuan XIE ; Mingzhi LI ; Jingcai LI ; Min WANG ; Shiqi WENG ; Lumei KANG ; Lingbao KONG
Chinese Journal of Cellular and Molecular Immunology 2025;41(8):735-743
Objective The study aims to investigate the immunological functions of the nucleocapsid (N) protein of the novel coronavirus Omicron (BA.1, BA.2) and evaluate the differences among different N proteins of mutant strains in immunogenicity. Methods By aligning sequences, the mutation sites of the Omicron (BA.1, BA.2) N protein relative to prototype strain of the novel coronavirus (Wuhan-Hu-1) were determined. The pET-28a-N-Wuhan-Hu-1 plasmid was used as template to construct pET-28a-BA.1/BA.2-N through single point mutation or homologous recombination. The three kinds of N protein were expressed in prokaryotic system, purified through Ni-NTA affinity chromatography, and then immunized into mice. The titer and reactivity of the polyclonal antibody, as well as the expression level of IL-1β and IFN-γ in mouse spleen cells, were detected using indirect ELISA and Western blot assay. Results The constructed prokaryotic expression plasmids were successfully used to express the Wuhan-Hu-1 N, BA.1 N, and BA.2 N proteins in E.coli BL21(DE3) at 37 DegreesCelsius for 4 hours. The indirect ELISA test showed that the titers of polyclonal antibody prepared by three N proteins were all 1:51 200. All three N proteins can increase the expression of IFN-γ and IL-1β cytokines, but the effect of Omicron N protein in activing two cytokines was more obvious than that of Wuhan-Hu-1 N protein. Conclusion The study obtained three new coronavirus N proteins and polyclonal antibodies, and confirmed that mutations in the amino acid sites of the N protein can affect its immunogenicity. This provides a basis for developing rapid diagnostic methods targeting N protein of different novel coronavirus variants.
Animals
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Mice
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SARS-CoV-2/genetics*
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Coronavirus Nucleocapsid Proteins/immunology*
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Nucleocapsid Proteins/isolation & purification*
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COVID-19/immunology*
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Antibodies, Viral/immunology*
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Mice, Inbred BALB C
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Interferon-gamma/metabolism*
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Interleukin-1beta/metabolism*
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Female
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Escherichia coli/metabolism*
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Mutation
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Humans

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