1.Changing resistance profiles of Haemophilus influenzae and Moraxella catarrhalis isolates in hospitals across China:results from the CHINET Antimicrobial Resistance Surveillance Program,2015-2021
Hui FAN ; Chunhong SHAO ; Jia WANG ; Yang YANG ; Fupin HU ; Demei ZHU ; Yunsheng CHEN ; Qing MENG ; Hong ZHANG ; Chun WANG ; Fang DONG ; Wenqi SONG ; Kaizhen WEN ; Yirong ZHANG ; Chuanqing WANG ; Pan FU ; Chao ZHUO ; Danhong SU ; Jiangwei KE ; Shuping ZHOU ; Hua ZHANG ; Fangfang HU ; Mei KANG ; Chao HE ; Hua YU ; Xiangning HUANG ; Yingchun XU ; Xiaojiang ZHANG ; Wenen LIU ; Yanming LI ; Lei ZHU ; Jinhua MENG ; Shifu WANG ; Bin SHAN ; Yan DU ; Wei JIA ; Gang LI ; Jiao FENG ; Ping GONG ; Miao SONG ; Lianhua WEI ; Xin WANG ; Ruizhong WANG ; Hua FANG ; Sufang GUO ; Yanyan WANG ; Dawen GUO ; Jinying ZHAO ; Lixia ZHANG ; Juan MA ; Han SHEN ; Wanqing ZHOU ; Ruyi GUO ; Yan ZHU ; Jinsong WU ; Yuemei LU ; Yuxing NI ; Jingrong SUN ; Xiaobo MA ; Yanqing ZHENG ; Yunsong YU ; Jie LIN ; Ziyong SUN ; Zhongju CHEN ; Zhidong HU ; Jin LI ; Fengbo ZHANG ; Ping JI ; Yunjian HU ; Xiaoman AI ; Jinju DUAN ; Jianbang KANG ; Xuefei HU ; Xuesong XU ; Chao YAN ; Yi LI ; Shanmei WANG ; Hongqin GU ; Yuanhong XU ; Ying HUANG ; Yunzhuo CHU ; Sufei TIAN ; Jihong LI ; Bixia YU ; Cunshan KOU ; Jilu SHEN ; Wenhui HUANG ; Xiuli YANG ; Likang ZHU ; Lin JIANG ; Wen HE ; Chunlei YUE
Chinese Journal of Infection and Chemotherapy 2025;25(1):30-38
Objective To investigate the distribution and antimicrobial resistance profiles of clinically isolated Haemophilus influenzae and Moraxella catarrhalis in hospitals across China from 2015 to 2021,and provide evidence for rational use of antimicrobial agents.Methods Data of H.influenzae and M.catarrhalis strains isolated from 2015 to 2021 in CHINET program were collected for analysis,and antimicrobial susceptibility testing was performed by disc diffusion method or automated systems according to the uniform protocol of CHINET.The results were interpreted according to the CLSI breakpoints in 2022.Beta-lactamases was detected by using nitrocefin disk.Results From 2015 to 2021,a total of 43 642 strains of Haemophilus species were isolated,accounting for 2.91%of the total clinical isolates and 4.07%of Gram-negative bacteria in CHINET program.Among the 40 437 strains of H.influenzae,66.89%were isolated from children and 33.11%were isolated from adults.More than 90%of the H.influenzae strains were isolated from respiratory tract specimens.The prevalence of β-lactamase was 53.79%in H.influenzae strains.The H.influenzae strains isolated from children showed higher resistance rate than the strains isolated from adults.Overall,779 strains of H.influenzae did not produce β-lactamase but were resistant to ampicillin(BLNAR).Beta-lactamase-producing strains showed significantly higher resistance rates to these antimicrobial agents than the β-lactamase-nonproducing strains.Of the 16 191 M.catarrhalis strains,80.06%were isolated from children and 19.94%isolated from adults.M.catarrhalis strains were mostly susceptible to both amoxicillin-clavulanic acid and cefuroxime,evidenced by resistance rate lower than 2.0%.Conclusions The emergence of antibiotic-resistant H.influenzae due to β-lactamase production poses a challenge for clinical anti-infective treatment.Therefore,it is very important to implement antibiotic resistance surveillance for H.influenzae and guide rational antibiotic use.All local clinical microbiology laboratories should actively improve antibiotic susceptibility testing and strengthen antibiotic resistance surveillance for H.influenzae.
2.Heterologous Expression,Purification and Enzymatic Characterization of Xylitol Dehydrogenase from the Thermophilic Fungus Talaromyces emersonii
Er MENG ; Cong QU ; Ke YI ; Hui-Min LI ; Xin-Yi DUAN ; Zhe-Yuan ZHANG ; Shao-Long HE ; Yu-Tao LUO ; Lei WU ; Dong-Yi ZHANG ; Chang-Jun LIU
Chinese Journal of Biochemistry and Molecular Biology 2025;41(7):1007-1018
The xylitol dehydrogenase(XDH)is a crucial enzyme involved in the xylose utilization in pentose-catabolizing yeasts and fungi.In addition to producing xylulose,XDH can also be employed to develop a biosensor for monitoring xylitol concentration.In this study,the gene encoding the thermophilic fungus Talaromyces emersonii XDH(TeXDH)was heterologously expressed in Escherichia coli BL21(DE3)at 16 ℃ in the soluble form.Recombinant TeXDH with high purity was purified by using a Ni-NTA affinity column.Size-exclusion chromatography and SDS-PAGE analysis demonstrated that the puri-fied recombinant TeXDH exists as a native trimer with a molecular mass of approximately 116 kD,and is composed of three identical subunits,each with a molecular weight of around 39 kD.The TeXDH strictly preferred NAD+as a coenzyme to NADP+.The optimal temperature and pH of the TeXDH were 40 ℃and 10.0,respectively.After EDTA treatment,the enzyme activity of TeXDH decreased to 43.26%of the initial enzyme activity,while the divalent metal ions Mg2+or Ca2+could recover the enzyme activity of TeXDH,reaching 103.32%and 110.69%of the initial enzyme activity,respectively,making them the optimal divalent metal ion cofactors for TeXDH enzyme.However,the divalent metal ions of Mn2+,Ni2+,Cu2+,Zn2+,Co2+,and Cd2+significantly inhibited the activity of TeXDH.ICP-MS and molecular doc-king studies revealed that 1 mol/L of TeXDH bound 2 mol/L Zn2+ions and 1 mol/L Mg2+ion.Further-more,TeXDH exhibited a high specificity for xylitol,laying the foundation for the development of future xylitol biosensors.
3.Interpretation of WHO Consolidated Guidelines on Tuberculosis. Module 4: Treatment-Tuberculosis Care and Support
Amin DUAN ; Xin GUAN ; Guichun DU ; Yu LIU
Chinese Journal of Modern Nursing 2025;31(26):3501-3506
Tuberculosis is a highly infectious disease that poses a significant threat to public health, particularly in resource-limited regions where its incidence remains high. In 2022, the World Health Organization (WHO) released the WHO Consolidated Guidelines on Tuberculosis. Module 4: Treatment- Tuberculosis Care and Support, aimed at improving the quality of care and treatment for tuberculosis patients. This guideline outlines the multifaceted challenges faced by tuberculosis patients during treatment and offers evidence-based intervention strategies. It highlights key areas such as psychological support, nutritional management, and social care. This paper provides an interpretation of the main contents of the guideline to offer evidence-based practice guidance for healthcare providers, and to support clinical staff in delivering targeted patient care interventions.
4.Analysis of clinical features and prognosis in pediatric malignant solid tumors of head and neck in single-center
Peiyi YANG ; Chao DUAN ; Shengcai WANG ; Mei JIN ; Dawei ZHANG ; Libing FU ; Tong YU ; Zhikai LIU ; Xiaoli MA ; Xin NI ; Yan SU
Journal of Capital Medical University 2025;46(3):545-552
Objective To summarize the clinical features and prognosis of children suffered from malignant solid tumors of head and neck.Methods The clinical data of children with primary malignant solid tumors located in the head and neck was retrospectively analyzed from January 2007 to December 2021 in the Department of Oncology,Beijing Children's Hospital,Capital Medical University,and the clinical features,prognostic factors were summarized.Results A total of 234 children with malignant solid tumors of head and neck were included,with a male to female ratio of 1∶0.7,aged from 3 months to 17 years and 6 months(median age 51 months).173 cases(73.9%)were treated with local painless masses.Other symptoms included snoring and facial paralysis.The proportion of rhabdomyosarcoma(RMS)was the highest(145 cases,62.0%),followed by neuroblastoma(NB)(25 cases,10.7%),Ewing sarcoma(19 cases,8.1%),etc.A total of 47 cases(20.1%)had distant metastasis.The patients received surgery,chemotherapy and radiotherapy under the mode of multidisciplinary treatment(MDT).The 3-year and 5-year overall survival(OS)were 80.8%and 75.8%,respectively,and the 3-year and 5-year progression free survival(PFS)were 64.0%and 58.9%,respectively.Tumor survivors had abnormal appearance or facial motor function(49 cases,41.2%),developmental problems or abnormal tooth loss(18 cases,15.1%),and other long-term complications that may be related to the tumor or treatment.Conclusion There are various pathologic types of pediatric head and neck malignant solid tumors,RMS and NB are the most common.Local painless mass was the most common complaint.Distant metastasis is an independent risk factor for the prognosis of head and neck malignant solid tumors.Under the MDT model,the prognosis of malignant solid tumors of the head and neck in our center was generally good.In the treatment of the tumors,the side effects and sequelae should be controlled as small as possible under the premise of long-term survival.
5.Resveratrol protects against oxidative stress damage during sperm cryopreservation by mediating the NRF2 signaling pathway
Lei XIN ; Yutong ZHANG ; Liting LIU ; Jing TAN ; Jingjing ZHANG ; Zongliu DUAN ; Yang GAO ; Jun YANG ; Biao YU ; Qunshan SHEN ; Xiaojin HE
Chinese Journal of Reproduction and Contraception 2025;45(10):1038-1046
Objective:To investigate the protective effects of resveratrol (RSV) on human sperm cryopreservation and explore its underlying protective mechanisms.Methods:A total of 165 normal fresh semen samples were collected from the Reproductive Medicine Center, Department of Obstetrics and Gynecology and Human Sperm Bank of the First Affiliated Hospital of Anhui Medical University between December 2022 and December 2024. Among them, 65 samples were used to obtain semen parameters before and after conventional freezing. Each sample of the other 104 samples was mixed at a 2∶1 volume ratio with cryoprotectant containing 0, 10 -?, 10 -?, or 10 -? mol/L RSV, followed by cryopreservation in liquid nitrogen for 24 h. Post-thaw assessments included routine sperm parameters, sperm DNA fragmentation index (DFI) evaluated by sperm chromatin dispersion assay, reactive oxygen species (ROS) levels measured via flow cytometry, RSV and nuclear factor erythroid 2-related factor 2 (NRF2) interactions examined by molecular docking and cellular thermal shift assay (CETSA), NRF2 protein contents analyzed by immunofluorescence and Western blotting, mRNA levels of NRF2 and downstream antioxidant proteins Heme Oxygenase-1 (HO-1) and NAD(P)H: quinone oxidoreductase 1 (NQO1) quantified by qRT-PCR and effects of NRF2 inhibitor ML385 on sperm parameters. Results:Compared with fresh samples, conventional cryopreservation significantly reduced sperm motility (all P<0.001). The addition of 10 -? mol/L RSV significantly improved the percentage of forward motile sperm after freezing (26.98%±8.98% vs. 19.61%±8.03%, P<0.001) while reducing DFI (9.84%±3.81% vs. 15.06%±4.22%, P<0.001) and ROS levels ( P<0.001) compared with the post-freezing group without the addition of RSV. Both molecular docking analysis and CETSA confirmed that RSV interacted with NRF2. Notably, sperm cryopreserved with 10 -? mol/L RSV exhibited significantly higher contents of NRF2 and its downstream effectors HO-1 and NQO1 compared with the post-freezing group without the addition of RSV (all P<0.001). This protective effect was markedly attenuated by co-treatment with the NRF2 inhibitor ML385, as evidenced by a significant decline in sperm motility ( P<0.001). Conclusion:RSV exerts cryoprotective effects likely through NRF2-mediated antioxidant pathways, reducing oxidative stress and enhancing post-thaw sperm quality.
6.Study on the Effects and Mechanism of Different Solvent Extracts from Jujing Pills in Improving Retinal Injury in Aging Mice with Kidney Yang Deficiency
Lei YUAN ; Hongqua YU ; Lingxin HUANG ; Xin LI ; Xiaoning HUANG ; Shulan SU ; Sheng GUO ; Jinao DUAN ; Yue ZHU
World Science and Technology-Modernization of Traditional Chinese Medicine 2025;27(11):3224-3239
Objective Evaluate the effects of different solvent extracts from Jujing Pills on improving retinal damage in kidney Yang deficiency aging mice and explore the underlying mechanism.Methods A composite modeling method of subcutaneous injection of D-galactose and hind limb injection of hydrocortisone was used to establish a kidney Yang deficiency type aging mouse model,and various solvent extract of Jujing Pills were given for intervention treatment.The improvement effect of different solvent extracts of Jujing Pills on aging mice with kidney Yang deficiency was evaluated by observing physical signs,measuring serum oxidative stress marker levels,and cyclic nucleotide levels.Optical coherence tomography(OCT)was used to detect the condition of the mouse retina,HE staining was used to detect the degree of retinal cell damage,TUNEL staining was used to detect retinal cell apoptosis,assay kit was used to detect oxidative stress factor expression,enzyme-linked immunosorbent assay was used to detect the expression of ciliary neurotrophic factor(CNTF),brain-derived neurotrophic factor(BDNF),and nerve growth factor(NGF)in the mouse eyeball,and Western blotting(WB)was used to quantitatively analyze the expression levels of apoptosis and neurotrophic pathway related proteins in the mouse retina tissue.Results Compared with the control group,the model group mice showed slow weight gain,reduced activity,decreased expression of antioxidant factors such as superoxide dismutase(SOD)and glutathione(GSH)in serum(P<0.01),and decreased cAMP/cGMP ratio(P<0.01).Different solvent extracts of Jujing Pills significantly increased the expression of antioxidant factors such as SOD and GSH(P<0.05),reduced the production of oxidative product malondialdehyde(MDA)(P<0.01),and increased the cAMP/cGMP ratio(P<0.01);Significantly increased the retinal thickness of model mice(P<0.01),improved retinal damage and inhibited retinal cell apoptosis(P<0.01),and significantly downregulated the ratio expression levels of Cleaved Caspase-3 and Caspase-3(P<0.01);The expression of CNTF,BDNF,and NGF was upregulated by water extracted medicinal residue alcohol extract,water extracted alcohol sediment,and total extract(P<0.01).The phosphorylation levels of CREB and ERK in the eyeball were significantly upregulated by water extracted medicinal residue alcohol extract and total extract(P<0.05).Conclusion Different solvent extracts of Jujing Pills can exert different pharmacological effects on improving retinal damage in aging mice with kidney yang deficiency model.Its mechanism of action is related to improving retinal apoptosis caused by oxidative stress and increasing the expression of nutritional factors.
7.Changing resistance profiles of Haemophilus influenzae and Moraxella catarrhalis isolates in hospitals across China:results from the CHINET Antimicrobial Resistance Surveillance Program,2015-2021
Hui FAN ; Chunhong SHAO ; Jia WANG ; Yang YANG ; Fupin HU ; Demei ZHU ; Yunsheng CHEN ; Qing MENG ; Hong ZHANG ; Chun WANG ; Fang DONG ; Wenqi SONG ; Kaizhen WEN ; Yirong ZHANG ; Chuanqing WANG ; Pan FU ; Chao ZHUO ; Danhong SU ; Jiangwei KE ; Shuping ZHOU ; Hua ZHANG ; Fangfang HU ; Mei KANG ; Chao HE ; Hua YU ; Xiangning HUANG ; Yingchun XU ; Xiaojiang ZHANG ; Wenen LIU ; Yanming LI ; Lei ZHU ; Jinhua MENG ; Shifu WANG ; Bin SHAN ; Yan DU ; Wei JIA ; Gang LI ; Jiao FENG ; Ping GONG ; Miao SONG ; Lianhua WEI ; Xin WANG ; Ruizhong WANG ; Hua FANG ; Sufang GUO ; Yanyan WANG ; Dawen GUO ; Jinying ZHAO ; Lixia ZHANG ; Juan MA ; Han SHEN ; Wanqing ZHOU ; Ruyi GUO ; Yan ZHU ; Jinsong WU ; Yuemei LU ; Yuxing NI ; Jingrong SUN ; Xiaobo MA ; Yanqing ZHENG ; Yunsong YU ; Jie LIN ; Ziyong SUN ; Zhongju CHEN ; Zhidong HU ; Jin LI ; Fengbo ZHANG ; Ping JI ; Yunjian HU ; Xiaoman AI ; Jinju DUAN ; Jianbang KANG ; Xuefei HU ; Xuesong XU ; Chao YAN ; Yi LI ; Shanmei WANG ; Hongqin GU ; Yuanhong XU ; Ying HUANG ; Yunzhuo CHU ; Sufei TIAN ; Jihong LI ; Bixia YU ; Cunshan KOU ; Jilu SHEN ; Wenhui HUANG ; Xiuli YANG ; Likang ZHU ; Lin JIANG ; Wen HE ; Chunlei YUE
Chinese Journal of Infection and Chemotherapy 2025;25(1):30-38
Objective To investigate the distribution and antimicrobial resistance profiles of clinically isolated Haemophilus influenzae and Moraxella catarrhalis in hospitals across China from 2015 to 2021,and provide evidence for rational use of antimicrobial agents.Methods Data of H.influenzae and M.catarrhalis strains isolated from 2015 to 2021 in CHINET program were collected for analysis,and antimicrobial susceptibility testing was performed by disc diffusion method or automated systems according to the uniform protocol of CHINET.The results were interpreted according to the CLSI breakpoints in 2022.Beta-lactamases was detected by using nitrocefin disk.Results From 2015 to 2021,a total of 43 642 strains of Haemophilus species were isolated,accounting for 2.91%of the total clinical isolates and 4.07%of Gram-negative bacteria in CHINET program.Among the 40 437 strains of H.influenzae,66.89%were isolated from children and 33.11%were isolated from adults.More than 90%of the H.influenzae strains were isolated from respiratory tract specimens.The prevalence of β-lactamase was 53.79%in H.influenzae strains.The H.influenzae strains isolated from children showed higher resistance rate than the strains isolated from adults.Overall,779 strains of H.influenzae did not produce β-lactamase but were resistant to ampicillin(BLNAR).Beta-lactamase-producing strains showed significantly higher resistance rates to these antimicrobial agents than the β-lactamase-nonproducing strains.Of the 16 191 M.catarrhalis strains,80.06%were isolated from children and 19.94%isolated from adults.M.catarrhalis strains were mostly susceptible to both amoxicillin-clavulanic acid and cefuroxime,evidenced by resistance rate lower than 2.0%.Conclusions The emergence of antibiotic-resistant H.influenzae due to β-lactamase production poses a challenge for clinical anti-infective treatment.Therefore,it is very important to implement antibiotic resistance surveillance for H.influenzae and guide rational antibiotic use.All local clinical microbiology laboratories should actively improve antibiotic susceptibility testing and strengthen antibiotic resistance surveillance for H.influenzae.
8.Heterologous Expression,Purification and Enzymatic Characterization of Xylitol Dehydrogenase from the Thermophilic Fungus Talaromyces emersonii
Er MENG ; Cong QU ; Ke YI ; Hui-Min LI ; Xin-Yi DUAN ; Zhe-Yuan ZHANG ; Shao-Long HE ; Yu-Tao LUO ; Lei WU ; Dong-Yi ZHANG ; Chang-Jun LIU
Chinese Journal of Biochemistry and Molecular Biology 2025;41(7):1007-1018
The xylitol dehydrogenase(XDH)is a crucial enzyme involved in the xylose utilization in pentose-catabolizing yeasts and fungi.In addition to producing xylulose,XDH can also be employed to develop a biosensor for monitoring xylitol concentration.In this study,the gene encoding the thermophilic fungus Talaromyces emersonii XDH(TeXDH)was heterologously expressed in Escherichia coli BL21(DE3)at 16 ℃ in the soluble form.Recombinant TeXDH with high purity was purified by using a Ni-NTA affinity column.Size-exclusion chromatography and SDS-PAGE analysis demonstrated that the puri-fied recombinant TeXDH exists as a native trimer with a molecular mass of approximately 116 kD,and is composed of three identical subunits,each with a molecular weight of around 39 kD.The TeXDH strictly preferred NAD+as a coenzyme to NADP+.The optimal temperature and pH of the TeXDH were 40 ℃and 10.0,respectively.After EDTA treatment,the enzyme activity of TeXDH decreased to 43.26%of the initial enzyme activity,while the divalent metal ions Mg2+or Ca2+could recover the enzyme activity of TeXDH,reaching 103.32%and 110.69%of the initial enzyme activity,respectively,making them the optimal divalent metal ion cofactors for TeXDH enzyme.However,the divalent metal ions of Mn2+,Ni2+,Cu2+,Zn2+,Co2+,and Cd2+significantly inhibited the activity of TeXDH.ICP-MS and molecular doc-king studies revealed that 1 mol/L of TeXDH bound 2 mol/L Zn2+ions and 1 mol/L Mg2+ion.Further-more,TeXDH exhibited a high specificity for xylitol,laying the foundation for the development of future xylitol biosensors.
9.Complete genomic sequence analysis of the G6P1bovine rotavirus BLL strain
Jin-hua ZHANG ; Xia-fei LIU ; Jun-jie YU ; Jia-xin FAN ; Ming-yue WANG ; Guang-ping XIONG ; Yi-peng WANG ; Dan-di LI ; Xiao-man SUN ; Li-li PANG ; Zhao-jun DUAN
Chinese Journal of Zoonoses 2025;41(1):8-14
Bovine rotavirus(BRV)is an important pathogen causing diarrhea in calves.To understand the genomic charac-teristics and genetic variations in bovine rotavirus,and to further enrich data on the biological characteristics of rotavirus,we aimed to amplify 11 gene segments of the isolated and cultured G6P[1]bovine rotavirus BLL strain,perform whole genome se-quencing,and analyze the molecular characteristics.MEGA7.0 and DNAMAN software were used for homology and typing a-nalysis,and the whole genome phylogenetic tree was constructed to analyze genetic evolution relationships.The complete geno-type of the BLL strain was G6-P[1]-I2-R2-C2-M2-A3-N2-T6-E2-H3.Phylogenetic analysis of the VP7 and VP4 genes of the BLL strain showed that the VP7 gene had the highest homology with RVA/Cow-wt/HB01/China/2021,and the VP4 gene of the BLL strain was in the same branch as RVA/Human-tc/ISR/Ro8059/1995.From the sequence alignment of VP8*amino acids,the sialic acid domain of the BLL strain was found to be similar to that in other P[1]strains,but different from those in other types of strains,except for residue 189,which was the same as that in Ro8059 but different from that in other strains.The results suggested that the BLL strain might potentially infect humans.Therefore,continued monitoring and study of the biological characteristics of this strain are necessary to provide more information and evidence supporting further research on the cross-species transmission of group A rotavirus in China.
10.Study on the correlation between H3N2 subtype influenza virus F195Y mutation and inadaptability in chicken embryos
Shunwu HUANG ; Jinyu DUAN ; Shiyu QI ; Hui LIU ; Ying SUN ; Weihua WU ; Xin WANG ; Yu′e HAO ; Shumei ZOU ; Dayan WANG ; Shisong FANG
Chinese Journal of Experimental and Clinical Virology 2025;39(2):175-181
Objective:This study aimed to explore the molecular mechanisms of the maladaptation of H3N2 influenza virus in chicken embryos, provide a theoretical basis for the restoration of H3N2 influenza vaccine production in chicken embryos.Methods:Samples of respiratory secretions from patients with influenza-like symptoms (Influenza-like Illness, ILI) caused by H3N2 influenza virus were inoculated into chicken embryos and Madin-Darby Canine Kidney cells (MDCK), respectively. After isolating the virus, hemagglutination experiments were conducted to detect hemagglutination titers and hemagglutination inhibition experiments were used to compare antigenic differences; further, whole-genome sequencing of H3N2 influenza virus was performed using second-generation high-throughput gene sequencing (Next Generation High-Throughput Gene Sequencing, NGS), and key amino acid sites of mutations were identified through sequence alignment; combined with sialic acid receptor binding experiments, the differences in the binding of wild-type and mutant receptor binding sites (RBS) to sialic acid receptors were compared; finally, molecular docking and molecular dynamics simulation method were used to explore the specific molecular mechanisms of how mutation sites affect the differences in the affinity of the RBS pocket for sialic acid receptors.Results:The hemagglutination assay result indicated that both chicken embryos and MDCK cells could isolate the influenza virus, and the hemagglutination inhibition test showed that no antigenic differences were produced in the isolated strains. NGS analysis revealed that the H3N2 virus underwent an F195Y mutation in the (RBS) region of the hemagglutinin (HA) protein after adaptation through chicken embryo passages. Receptor-binding experiments demonstrated that the F195Y mutation enhanced the virus′s binding ability to α2, 3-linked sialic acid glycan (Neu5Acα2-3Galβ1-4GlcNAcβ-PAA, 3′SLN), while the mutation did not affect the affinity of the RBS pocket for α2, 6-linked sialic acid glycan (Neu5Acα2-6Galβ1-4GlcNAcβ-PAA, 6′SLN). Molecular docking and molecular dynamics simulation result indicate that the F195Y mutation, by replacing a hydrophobic amino acid with a hydrophilic one, leads to a significant decrease in the structure of the RBS pocket, enhancing the binding stability of the H3N2 influenza virus with α2, 3-sln. This is specifically manifested by an increase in binding time and an increase in the number of hydrogen bonds at the RBS site with the receptor. Furthermore, the F195Y mutation does not alter the binding of the virus to other receptors.Conclusions:The F195Y mutation in the RBS pocket of H3N2 influenza virus is a key site affecting the viral chicken embryo inadaptability.

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