1.Differences in deltamethrin resistance and kdr gene mutation in Culex tritaeniorhynchus population in and outside the Yellow Sea wetland
Xiao-er ZHANG ; Zhi-ming WU ; Ye TIAN ; Qian CUI ; Yu-qian JI ; Huan WANG ; Shu-juan YANG ; Yi-chao ZHAO ; Yu WANG ; Hua-yu YIN ; Yu DING ; Guo-jin YAN ; Min-sen ZHAO ; Shou-gang ZHANG ; Bing-dong SONG ; Hong-na CHEN ; Jian GAO ; Wei-fang YANG ; Yu-fu ZHANG ; Hui LIU ; Hong-liang CHU
Acta Parasitologica et Medica Entomologica Sinica 2026;33(2):101-107
Objective To gain insights into the biological characteristics of different populations of Culex tritaeniorhynchus within and around the Yellow Sea wetland from the perspective of the occurrence of resistance, we investigated the levels of resistance to deltamethrin and kdr gene mutation in the wetland and its peripheral areas. Methods Specimens were collected from Cx. tritaeniorhynchus populations at two monitoring sites in the Rare Bird National Nature Reserve and Tiaozi Ni Wetland Scenic Area, and also from two populations in Yancheng City and the Liuhe District of Nanjing, and the resistance of these mosquitoes to deltamethrin was determined using the CDC biotest bottle method. For each concentration of deltamethrin assessed, a random subset of exposed specimens was selected for amplification of the kdr gene fragment, followed by Sanger sequencing to identify and analyze resistance-associated mutations. Results The LC50 levels of deltamethrin among mosquitoes from the four populations in Luhe, Yancheng, the Rare Bird National Nature Reserve and the Tiaozi Ni Wetland Scenic Area were 2.048 5, 7.798 2, 3.473 3, and 17.695 5 mg/mL, respectively, with corresponding concentrations of deltamethrin ranging from 0.005 to 5.000,0.050 to 50.000,0.050 to 25.000 and 0.050 to 50.000 mg/mL, respectively. Furthermore, the ranges of the KT50 values were 11.76-107.43, 67.05-216.30,29.77-107.43 and 28.40-329.51 min; the 1-h knockdown rates were 34.58%-99.15%, 9.52%-43.80%, 55.09%-73.01%, and 10.09%-68.07%; and the 24-h mortality rates were 12.15%-67.52%,9.52%-79.56%,13.17%-82.21%, and 11.01%-78.99%, respectively. With respect to kdr gene mutation, we assayed a total of 63,70,59, and 57 mosquitoes for the four populations, for which we detected L1014F mutation frequencies of 14.29%, 35.00%, 20.34%, and 31.58%, respectively, with a majority of these mutations being heterozygous for resistance. In addition, five adult mosquitoes were identified has having synonymous mutations at site 1011[i. e. , AAT(asparagine)mutation to AAC(asparagine)]. Conclusions Our findings revealed the clear resistance of Cx. tritaeniorhynchus to deltamethrin in the Yancheng region of the Yellow Sea wetland, and the resistance phenotype and kdr frequency of Cx. tritaeniorhynchus in the wetland environment were comparable to those of Cx. tritaeniorhynchus in the wetland environment, thereby indicating that the resistance of different populations of Cx. tritaeniorhynchus was homogeneous under the pressure of different insecticide selection within and around the wetland. However, the underlying mechanisms need to be further studied.
2.Guideline for Adult Weight Management in China
Weiqing WANG ; Qin WAN ; Jianhua MA ; Guang WANG ; Yufan WANG ; Guixia WANG ; Yongquan SHI ; Tingjun YE ; Xiaoguang SHI ; Jian KUANG ; Bo FENG ; Xiuyan FENG ; Guang NING ; Yiming MU ; Hongyu KUANG ; Xiaoping XING ; Chunli PIAO ; Xingbo CHENG ; Zhifeng CHENG ; Yufang BI ; Yan BI ; Wenshan LYU ; Dalong ZHU ; Cuiyan ZHU ; Wei ZHU ; Fei HUA ; Fei XIANG ; Shuang YAN ; Zilin SUN ; Yadong SUN ; Liqin SUN ; Luying SUN ; Li YAN ; Yanbing LI ; Hong LI ; Shu LI ; Ling LI ; Yiming LI ; Chenzhong LI ; Hua YANG ; Jinkui YANG ; Ling YANG ; Ying YANG ; Tao YANG ; Xiao YANG ; Xinhua XIAO ; Dan WU ; Jinsong KUANG ; Lanjie HE ; Wei GU ; Jie SHEN ; Yongfeng SONG ; Qiao ZHANG ; Hong ZHANG ; Yuwei ZHANG ; Junqing ZHANG ; Xianfeng ZHANG ; Miao ZHANG ; Yifei ZHANG ; Yingli LU ; Hong CHEN ; Li CHEN ; Bing CHEN ; Shihong CHEN ; Guiyan CHEN ; Haibing CHEN ; Lei CHEN ; Yanyan CHEN ; Genben CHEN ; Yikun ZHOU ; Xianghai ZHOU ; Qiang ZHOU ; Jiaqiang ZHOU ; Hongting ZHENG ; Zhongyan SHAN ; Jiajun ZHAO ; Dong ZHAO ; Ji HU ; Jiang HU ; Xinguo HOU ; Bimin SHI ; Tianpei HONG ; Mingxia YUAN ; Weibo XIA ; Xuejiang GU ; Yong XU ; Shuguang PANG ; Tianshu GAO ; Zuhua GAO ; Xiaohui GUO ; Hongyi CAO ; Mingfeng CAO ; Xiaopei CAO ; Jing MA ; Bin LU ; Zhen LIANG ; Jun LIANG ; Min LONG ; Yongde PENG ; Jin LU ; Hongyun LU ; Yan LU ; Chunping ZENG ; Binhong WEN ; Xueyong LOU ; Qingbo GUAN ; Lin LIAO ; Xin LIAO ; Ping XIONG ; Yaoming XUE
Chinese Journal of Endocrinology and Metabolism 2025;41(11):891-907
Body weight abnormalities, including overweight, obesity, and underweight, have become a dual public health challenge in Chinese adults: overweight and obesity lead to a variety of chronic complications, while underweight increases the risks of malnutrition, sarcopenia, and organ dysfunction. To systematically address these issues, multidisciplinary experts in endocrinology, sports science, nutrition, and psychiatry from various regions have held multiple weight management seminars. Based on the latest epidemiological data and clinical evidence, they expanded the guideline to include assessment and intervention strategies for underweight, in addition to the core content of obesity management. This guideline outlines the etiological mechanisms, evaluation methods, and multidimensional management strategies for overweight and obesity, covering key areas such as diagnosis and assessment, medical nutrition therapy, exercise prescription, pharmacological intervention, and psychological support. It is intended to provide a scientific and standardized approach to weight management across the adult population, aiming to curb the rising prevalence of obesity, mitigate complications associated with abnormal body weight, and improve nutritional status and overall quality of life.
3.Clinical trail of vericiguat combined with sacubitril valsartan sodium in the treatment of patients with heart failure with reduced ejection fraction
Miao-jun WANG ; Shi-ping XU ; Xiao-jin PAN ; Zhi-dong YE ; Yu-fang LIAN ; Jun QIU ; Shao-tang LU ; Sheng-jie ZHOU
The Chinese Journal of Clinical Pharmacology 2025;41(1):6-10
Objective To observe the clinical efficacy and safety of vericiguat tablets combined with sacubitril valsartan sodium(Sac/Val)tablets in the treatment of patients with heart failure with reduced ejection fraction(HFrEF).Methods The HFrEF patients were divided into control group and treatment group according to the cohort method.The control group was treated with Sac/Val tablets 200 mg per time,bid,orally.On the basis of control group,the treatment group was treated with vericiguat tablets 2.5 mg per time,qd,taken with meal.Two groups were treated for 3 months.The clinical efficacy,left ventricular ejection fraction(LVEF),left ventricular end-diastolic dimension(LVEDD)and end-systolic diameter(LVESD),levels of high sensitivity C-reactive protein(hs-CRP),interleukin-6(IL-6),nitric oxide(NO),N-terminal pro-brain natriuretic peptide(NT-proBNP),blood urea nitrogen(BUN)and serum creatinine(SCr),and safety were compared between the two groups.During follow-up,the heart failure rehospitalization rates and major adverse cardiovascular events were compared between the two groups.Results Treatment group was enrolled 53 patients,control group was enrolled 53 patients.After treatment,the total effective rates of treatment and control groups were 94.34%(50 cases/53 cases)and 81.13%(43 cases/53 cases)with statistical significant difference(P<0.05).After treatment,the LVEF of treatment and control groups were(48.02±5.20)%and(43.02±4.33)%,the LVEDDs were(52.85±6.30)and(55.63±6.88)mm,the LVESDs were(41.64±6.40)and(44.22±5.85)mm,the levels of hs-CRP were(10.22±2.63)and(14.60±2.98)mg L-1,the levels of IL-6 were(14.48±2.40)and(17.36±2.52)pg·mL-1,the levels of NO were(102.60±20.16)and(92.16±16.33)μmol·L-1,the levels of NT-proBNP were(898.74±102.20)and(1315.60±182.64)ng·L-1,the levels of BUN were(12.02±2.28)and(13.45±2.33)mmol·L-1,the levels of SCr were(82.22±5.89)and(85.64±6.03)μmol·L-1,the heart failure rehospitalization rates were 5.66%and 13.21%,respectively;the differences were statistical significant between two groups(all P<0.05).The adverse drug reactions of treatment group were hyperkalemia,hypotension,renal dysfunction,dizziness and headache,while those in control group were renal dysfunction,hyperkalemia,and hypotension.The major adverse cardiovascular events of treatment group were angina pectoris and acute myocardial infarction,while those in control group were angina pectoris,acute myocardial infarction and atrial fibrillation.The incidences of total adverse drug reactions in treatment and control groups were 13.21%and 7.55%,the incidences of major adverse cardiovascular events were 5.66%and 13.21%,respectively,without statistically significant differences(all P>0.05).Conclusion Vericiguat tablets combined with Sac/Val tablets have a definitive clinical efficacy in the treatment of HFrEF patients,which can improve cardiac and endothelial function,reduce inflammatory response and readmission times,without increasing the incidences of adverse drug reactions.
4.The Expression Characteristics,Clinical Relevance and Tumor Inhibition of KCNN3 in Gastric Adenocarcinoma
Zi-Qing ZHAN ; Jia-Bei JIN ; Yu-Xuan LI ; Jia-Xin SHI ; Meng YE ; Xiao-Feng JIN
Chinese Journal of Biochemistry and Molecular Biology 2025;41(4):560-575,中插1-中插4
Potassium-calcium activates channel subfamily N member 3(KCNN3/SK3/KCa2.3)is in-volved in regulating cellular calcium signaling,muscle contraction and neurotransmitter release.Dysregu-lation of the KCNN3 channel is associated with the development of various tumors.We use bioinformatics analysis to identify whether KCNN3 regulates the occurrence and development of stomach adenocarcinoma(STAD)as a prognostic target.By analyzing the Human Protein Atlas(HPA)database and The Cancer Genome Atlas(TCGA)database,we found that the protein and mRNA levels of KCNN3 were dramatic-ally reduced in STAD,and TCGA database showed that KCNN3 significantly correlated with the prognosis and clinical features of STAD.In addition,we found that high expression of KCNN3 in STAD reduced the IC50 of several drugs in STAD cells,suggesting that high expression of KCNN3 correlated with the drug sensitivity of STAD.To investigate the underlying biological mechanism,we identified a potential KCNN3 interaction factor,tumor necrosis factor receptor superfamily member 7(CD27/TNFRSF7),which is expressed at low levels in STAD.RT-qPCR and Western blotting confirmed that KCNN3 and CD27 positively correlated with each other at protein and mRNA levels,and co-immunoprecipitation and immunofluorescence experiments confirmed that the two proteins interact and colocalize in the cytoplasm.Moreover,we confirmed the inhibitory effect of KCNN3 on the proliferation,migration and invasion of hu-man STAD cells in vitro and in vivo through subcutaneous tumorigenesis and cellular experiments.Fur-thermore,GO/KEGG enrichment analysis showed that KCNN3 was enriched in signaling pathways regula-ting the immune response and calcium or metal ion transport.Lastly,we verified through cell co-culture,RT-qPCR and CCK8 assays that high expression of KCNN3 can promote the increase of T cell activating factor and the killing effect of T cells on STAD cells.Therefore,our results suggest that KCNN3 is a po-tential inhibitory factor affecting the occurrence and progression of STAD.
5.Selection of exosomal microRNA biomarkers for brucellosis diagnosis and construction of a potential miRNA-mRNA regulation network
Jin ZHAO ; Zhi-qiang CHEN ; Bing-Li WANG ; Shu-ling LI ; Xiao-yu ZHU ; Jin-tong JIA ; Ye-zi LIU ; Zhi-wei LI
Chinese Journal of Zoonoses 2025;41(3):269-277
This study was aimed at exploring novel auxiliary diagnostic biomarkers for brucellosis and their potential miR-NA-mRNA regulatory networks.High-throughput sequencing was used to compare miRNA expression differences in serum ex-osomes between patients with brucellosis and healthy controls.Subsequently,RT-qPCR was used to validate the expression of significantly upregulated exosomal miRNAs.The diagnostic value of these miRNAs was assessed with ROC curves,and bioin-formatics analyses were performed to investigate the potential roles of the miRNAs in brucellosis infection.The ROC curve a-nalysis indicated that the area under the curve for exosomal hsa-miR-11400(P<0.05),hsa-miR-199a-5p(P<0.05),and hsa-miR-148a-5p(P<0.05)was 0.79,0.81,and 0.74,respectively.A total of 465 differentially expressed miRNAs and their tar-get genes were predicted,including 25 immune-related target genes,most of which were closely associated with cancer-related proteoglycans,NF-kappa B signaling pathways,and IL-17 signaling pathways.The constructed differentially expressed gene network indicated that the immune genes PLXNA2,IL17RA,PRKCA,CD22,ACVR1B,and CBL might be regulated by hsa-miR-199a-5p and hsa-miR-148a-5p.These findings suggest that exosomal miRNAs might serve as auxiliary diagnostic indicators for brucellosis.Our exosomal miRNA-mRNA regulatory network provides new insights into the pathogenesis and treatment of brucellosis.
6.Effect of rosavin on hepatocellular steatosis and its underlying mechanism
Shen WANG ; Jin-hui CAI ; Lin ZHENG ; Yan ZHANG ; Kai-qing ZENG ; Qi-en XU ; Yan-min FENG ; Xiao-xia YE
Chinese Pharmacological Bulletin 2025;41(3):466-474
Aim To investigate the effects of rosavin on hepatocellular steatosis and its mechanism of action.Methods AML-12 and HepG2 cells were induced to undergo hepatocellular steatosis by free fatty acids(FFA),and the optimal inducing concentration was determined by oil red O staining and CCK-8 assay.The cell activity was detected by CCK-8 assay after ro-savin treatment,and the lipid droplet accumulation was observed by oil red O staining.The levels of triglycer-ide(TG),total cholesterol(TC),glutamic oxalacetic transaminase(AST),glutamic pyruvic transaminase(ALT),superoxide dismutase(SOD),glutathione per-oxidase(GSH-Px),and malondialdehyde(MDA)were detected by kits.The potential targets of rosavin in non-alcoholic fatty liver disease(NAFLD)were ana-lyzedby network pharmacology and molecular docking,and the expression of core candidate targets before and after the rosavin intervention was detected by real-time fluorescence quantitative PCR.Results Hepatocyte steatosis was induced by FFA,and the intervention of rosavin(25,50 μmol·L-1)reduced the number of intracellular lipid droplets in hepatocytes in a dose-de-pendent manner,also lowered the cellular levels of TG,TC,AST,ALT,elevated the levels of SOD and GSH-Px,and reduced the levels of MDA.Network pharma-cological analysis and molecular docking yielded five core candidate targets:NOS3,MAPK14,PPARG,TNF-α,and IGF-1,and real-time fluorescence quantitative PCR showed that the action of loxavir significantly re-duced the gene expression of TNF-α and PPARG in hepatocytes after FFA induction.Conclusions Rosa-vin can attenuate the inflammatory response,oxidative stress level,and lipid accumulation in hepatocytes by modulating TNF-α and PPARG,thereby ameliorating FFA-induced hepatocellular steatosis.
7.Guideline for Adult Weight Management in China
Weiqing WANG ; Qin WAN ; Jianhua MA ; Guang WANG ; Yufan WANG ; Guixia WANG ; Yongquan SHI ; Tingjun YE ; Xiaoguang SHI ; Jian KUANG ; Bo FENG ; Xiuyan FENG ; Guang NING ; Yiming MU ; Hongyu KUANG ; Xiaoping XING ; Chunli PIAO ; Xingbo CHENG ; Zhifeng CHENG ; Yufang BI ; Yan BI ; Wenshan LYU ; Dalong ZHU ; Cuiyan ZHU ; Wei ZHU ; Fei HUA ; Fei XIANG ; Shuang YAN ; Zilin SUN ; Yadong SUN ; Liqin SUN ; Luying SUN ; Li YAN ; Yanbing LI ; Hong LI ; Shu LI ; Ling LI ; Yiming LI ; Chenzhong LI ; Hua YANG ; Jinkui YANG ; Ling YANG ; Ying YANG ; Tao YANG ; Xiao YANG ; Xinhua XIAO ; Dan WU ; Jinsong KUANG ; Lanjie HE ; Wei GU ; Jie SHEN ; Yongfeng SONG ; Qiao ZHANG ; Hong ZHANG ; Yuwei ZHANG ; Junqing ZHANG ; Xianfeng ZHANG ; Miao ZHANG ; Yifei ZHANG ; Yingli LU ; Hong CHEN ; Li CHEN ; Bing CHEN ; Shihong CHEN ; Guiyan CHEN ; Haibing CHEN ; Lei CHEN ; Yanyan CHEN ; Genben CHEN ; Yikun ZHOU ; Xianghai ZHOU ; Qiang ZHOU ; Jiaqiang ZHOU ; Hongting ZHENG ; Zhongyan SHAN ; Jiajun ZHAO ; Dong ZHAO ; Ji HU ; Jiang HU ; Xinguo HOU ; Bimin SHI ; Tianpei HONG ; Mingxia YUAN ; Weibo XIA ; Xuejiang GU ; Yong XU ; Shuguang PANG ; Tianshu GAO ; Zuhua GAO ; Xiaohui GUO ; Hongyi CAO ; Mingfeng CAO ; Xiaopei CAO ; Jing MA ; Bin LU ; Zhen LIANG ; Jun LIANG ; Min LONG ; Yongde PENG ; Jin LU ; Hongyun LU ; Yan LU ; Chunping ZENG ; Binhong WEN ; Xueyong LOU ; Qingbo GUAN ; Lin LIAO ; Xin LIAO ; Ping XIONG ; Yaoming XUE
Chinese Journal of Endocrinology and Metabolism 2025;41(11):891-907
Body weight abnormalities, including overweight, obesity, and underweight, have become a dual public health challenge in Chinese adults: overweight and obesity lead to a variety of chronic complications, while underweight increases the risks of malnutrition, sarcopenia, and organ dysfunction. To systematically address these issues, multidisciplinary experts in endocrinology, sports science, nutrition, and psychiatry from various regions have held multiple weight management seminars. Based on the latest epidemiological data and clinical evidence, they expanded the guideline to include assessment and intervention strategies for underweight, in addition to the core content of obesity management. This guideline outlines the etiological mechanisms, evaluation methods, and multidimensional management strategies for overweight and obesity, covering key areas such as diagnosis and assessment, medical nutrition therapy, exercise prescription, pharmacological intervention, and psychological support. It is intended to provide a scientific and standardized approach to weight management across the adult population, aiming to curb the rising prevalence of obesity, mitigate complications associated with abnormal body weight, and improve nutritional status and overall quality of life.
8.The Expression Characteristics,Clinical Relevance and Tumor Inhibition of KCNN3 in Gastric Adenocarcinoma
Zi-Qing ZHAN ; Jia-Bei JIN ; Yu-Xuan LI ; Jia-Xin SHI ; Meng YE ; Xiao-Feng JIN
Chinese Journal of Biochemistry and Molecular Biology 2025;41(4):560-575,中插1-中插4
Potassium-calcium activates channel subfamily N member 3(KCNN3/SK3/KCa2.3)is in-volved in regulating cellular calcium signaling,muscle contraction and neurotransmitter release.Dysregu-lation of the KCNN3 channel is associated with the development of various tumors.We use bioinformatics analysis to identify whether KCNN3 regulates the occurrence and development of stomach adenocarcinoma(STAD)as a prognostic target.By analyzing the Human Protein Atlas(HPA)database and The Cancer Genome Atlas(TCGA)database,we found that the protein and mRNA levels of KCNN3 were dramatic-ally reduced in STAD,and TCGA database showed that KCNN3 significantly correlated with the prognosis and clinical features of STAD.In addition,we found that high expression of KCNN3 in STAD reduced the IC50 of several drugs in STAD cells,suggesting that high expression of KCNN3 correlated with the drug sensitivity of STAD.To investigate the underlying biological mechanism,we identified a potential KCNN3 interaction factor,tumor necrosis factor receptor superfamily member 7(CD27/TNFRSF7),which is expressed at low levels in STAD.RT-qPCR and Western blotting confirmed that KCNN3 and CD27 positively correlated with each other at protein and mRNA levels,and co-immunoprecipitation and immunofluorescence experiments confirmed that the two proteins interact and colocalize in the cytoplasm.Moreover,we confirmed the inhibitory effect of KCNN3 on the proliferation,migration and invasion of hu-man STAD cells in vitro and in vivo through subcutaneous tumorigenesis and cellular experiments.Fur-thermore,GO/KEGG enrichment analysis showed that KCNN3 was enriched in signaling pathways regula-ting the immune response and calcium or metal ion transport.Lastly,we verified through cell co-culture,RT-qPCR and CCK8 assays that high expression of KCNN3 can promote the increase of T cell activating factor and the killing effect of T cells on STAD cells.Therefore,our results suggest that KCNN3 is a po-tential inhibitory factor affecting the occurrence and progression of STAD.
9.Selection of exosomal microRNA biomarkers for brucellosis diagnosis and construction of a potential miRNA-mRNA regulation network
Jin ZHAO ; Zhi-qiang CHEN ; Bing-Li WANG ; Shu-ling LI ; Xiao-yu ZHU ; Jin-tong JIA ; Ye-zi LIU ; Zhi-wei LI
Chinese Journal of Zoonoses 2025;41(3):269-277
This study was aimed at exploring novel auxiliary diagnostic biomarkers for brucellosis and their potential miR-NA-mRNA regulatory networks.High-throughput sequencing was used to compare miRNA expression differences in serum ex-osomes between patients with brucellosis and healthy controls.Subsequently,RT-qPCR was used to validate the expression of significantly upregulated exosomal miRNAs.The diagnostic value of these miRNAs was assessed with ROC curves,and bioin-formatics analyses were performed to investigate the potential roles of the miRNAs in brucellosis infection.The ROC curve a-nalysis indicated that the area under the curve for exosomal hsa-miR-11400(P<0.05),hsa-miR-199a-5p(P<0.05),and hsa-miR-148a-5p(P<0.05)was 0.79,0.81,and 0.74,respectively.A total of 465 differentially expressed miRNAs and their tar-get genes were predicted,including 25 immune-related target genes,most of which were closely associated with cancer-related proteoglycans,NF-kappa B signaling pathways,and IL-17 signaling pathways.The constructed differentially expressed gene network indicated that the immune genes PLXNA2,IL17RA,PRKCA,CD22,ACVR1B,and CBL might be regulated by hsa-miR-199a-5p and hsa-miR-148a-5p.These findings suggest that exosomal miRNAs might serve as auxiliary diagnostic indicators for brucellosis.Our exosomal miRNA-mRNA regulatory network provides new insights into the pathogenesis and treatment of brucellosis.
10.Isolation,identification,and biological characterization of enterotoxigenic Escherichia coli from a South China tiger
Jing-ru XU ; Zhi-hao ZHU ; Yu-qi LI ; Si-si FAN ; Ya-li KANG ; Yu-bin ZHUO ; Ling-shan HUANG ; Shu-qi QIU ; XUE-YUXI ; Xiao-ping WU ; Yu-ting LIAO ; Wei-ye LIN ; Xiao-ziyi XIAO ; Xue-jin LI ; Teng-teng CHEN ; Xi-pan LIN ; Kai-xiong LIN ; Ke-wei FAN
Chinese Journal of Zoonoses 2025;41(6):567-573
This study was aimed at identifying the pathogenic bacteria responsible for the death of a young tiger at the Fujian Meihua Mountain South China Tiger Breeding Research Institute.Tissue samples from the lungs,liver,and intestines of the deceased tiger were collected,and the bacteria were cultured inasterile environment.The bacterial strains were characterized according to their morphological and molecular biological properties,including assessment of virulence genes and antibiotic resistance genes,mouse lethality tests,and antibiotic susceptibility evaluations.A predominant bacterial strain isolated from the liver of the deceased tiger was identified as enterotoxigenic Escherichia coli(ETEC)strain Tiger22513F.Phylogenetic analysis of the 16S rRNA gene revealed that the Tiger22513F strain exhibited close genetic similarity to the reference strain ETEC(MF919609.1),with 99.9%nucleotide similarity,and resided on the same evolutionary branch.The Tiger22513F strain contained 11 antibiotic resistance genes(tetA,sul1,sul3,cmlA,floR,blaTEM,blaSHV,blaCMY-2,qnrA,qnrS,and qnrD)along with five virulence genes(VT1,fyuA,tsh,iucD,and ST).Mouse lethality tests indicated significant pathogenicity toward mice,affecting primarily the lungs,liver,and intestines.Antibiotic susceptibility testing demonstrated that this strain exhibited resistance to various classes of beta-lactam antibiotics,as well as quinolones and aminoglycosides.This investigation successfully isolated a multi-drug resistant enterotoxigenic Escherichia coli strain with pronounced pathogenicity from the liver of a deceased tiger;thus providing valuable scientific insights for clinical diagnosis,as well as prevention and control measures,against ETEC infections in South China tigers.


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