ObjectiveTo investigate the ameliorative effect of Wendantang combined with Danshenyin and Dushentang （WDD） on mice with ischemic heart disease （IHD） presenting phlegm-stasis syndrome based on the inflammatory phenotype and differentiation of circulating monocytes. MethodsA model of IHD with phlegm-stasis syndrome was established using left anterior descending coronary artery ligation supplemented with a high-fat diet. Eighty model mice were randomly assigned to the model group， WDD low-dose group （WDD-L）， WDD medium-dose group （WDD-M）， WDD high-dose group （WDD-H）， and atorvastatin calcium tablet group， with 16 mice in each group. An additional 16 C57BL/6J mice were designated as the sham-operation group. The WDD groups received intragastric administration at doses of 8.91， 17.81， 35.62 g·kg^-1， and the atorvastatin calcium tablet group received the corresponding drug at 1.3 mg·kg^-1， twice daily. The sham-operation and model groups were given the same volume of pure water by gavage each day. After 5 consecutive weeks of administration， the cardiac index was calculated. Cardiac function was assessed by echocardiography. Myocardial histopathology was examined by hematoxylin-eosin （HE） staining. Serum N-terminal pro-B-type natriuretic peptide （pro-BNP） content was measured by enzyme-linked immunosorbent assay （ELISA）. Hemorheological parameters were analyzed using an automated hemorheology analyzer. Serum levels of total cholesterol （TC）， triglycerides （TG）， low-density lipoprotein （LDL）， and high-density lipoprotein （HDL） were determined using an automated biochemical analyzer. Changes in circulating monocytes were detected by flow cytometry. Mouse bone marrow mononuclear cells were isolated in vitro and divided into blank group， model serum group， WDD-L drug-containing serum group， WDD-M drug-containing serum group， and WDD-H drug-containing serum group. CD36 expression and macrophage differentiation in each group were assessed by flow cytometry. The mechanism by which WDD mediates circulating monocyte differentiation was further explored using CD36 knockdown/overexpression RAW264.7 cell lines. ResultsCompared with the sham-operation group， the model group showed a significantly increased cardiac index （P0.01）， significantly decreased fractional shortening （FS） （P0.01）， and significantly increased left ventricular end-diastolic internal diameter （LVDD） and left ventricular end-systolic internal diameter （LVDS） （P0.01）. Cardiomyocytes exhibited marked deformation and necrosis with inflammatory cell infiltration. Serum pro-BNP levels were significantly elevated （P0.01）， and whole-blood viscosity （BV） at high， medium， and low shear rates was significantly increased （P0.01）. Compared with the model group， the WDD groups showed significantly reduced cardiac index （P0.05， P0.01）， significantly increased FS （P0.05， P0.01）， significantly decreased LVDD and LVDS （P0.01）， markedly improved cardiomyocyte morphology， significantly reduced inflammatory infiltration， significantly decreased serum pro-BNP levels （P0.01）， and significantly decreased BV at high， medium， and low shear rates （P0.01）， with the most pronounced improvement observed in the WDD-M group. Compared with the sham-operation group， TC， TG， and LDL levels were significantly increased in the model group （P0.05， P0.01）， while HDL levels were significantly decreased （P0.05）. After WDD-H treatment， TC， TG， and LDL levels were significantly reduced and HDL levels were significantly increased in mice （P0.05， P0.01）. Compared with the sham-operation group， classical monocytes in blood and bone marrow and intermediate monocytes in blood were significantly increased in the model group （P0.01）， whereas intermediate monocytes in bone marrow and non-classical monocytes in blood were significantly decreased （P0.01）. After WDD administration， all circulating monocyte subsets in blood and bone marrow were significantly alleviated （P0.05， P0.01）， with the WDD-M group showing the optimal effect. In vitro， compared with the blank group， CD36 expression on bone marrow monocytes and the proportion of differentiated macrophages were significantly increased in the model serum group （P0.01）， and CD36 expression was significantly upregulated on RAW264.7 cells （P0.01）. Compared with the model serum group， all drug-containing serum groups exhibited significantly reduced CD36 expression on bone marrow monocytes and significantly reduced macrophage differentiation （P0.01）. WDD downregulated CD36 expression in both CD36 knockdown and overexpression RAW264.7 cell lines （P0.05， P0.01）， with the strongest regulatory effect observed in the WDD-M drug-containing serum group. ConclusionWDD can significantly improve the manifestations of phlegm-stasis syndrome in IHD mice and reduce the proportion of classical circulating monocytes. Its mechanism may be related to the inhibition of CD36 expression on classical circulating monocytes.

ObjectiveTo investigate the ameliorative effect of Wendantang combined with Danshenyin and Dushentang （WDD） on mice with ischemic heart disease （IHD） presenting phlegm-stasis syndrome based on the inflammatory phenotype and differentiation of circulating monocytes. MethodsA model of IHD with phlegm-stasis syndrome was established using left anterior descending coronary artery ligation supplemented with a high-fat diet. Eighty model mice were randomly assigned to the model group， WDD low-dose group （WDD-L）， WDD medium-dose group （WDD-M）， WDD high-dose group （WDD-H）， and atorvastatin calcium tablet group， with 16 mice in each group. An additional 16 C57BL/6J mice were designated as the sham-operation group. The WDD groups received intragastric administration at doses of 8.91， 17.81， 35.62 g·kg^-1， and the atorvastatin calcium tablet group received the corresponding drug at 1.3 mg·kg^-1， twice daily. The sham-operation and model groups were given the same volume of pure water by gavage each day. After 5 consecutive weeks of administration， the cardiac index was calculated. Cardiac function was assessed by echocardiography. Myocardial histopathology was examined by hematoxylin-eosin （HE） staining. Serum N-terminal pro-B-type natriuretic peptide （pro-BNP） content was measured by enzyme-linked immunosorbent assay （ELISA）. Hemorheological parameters were analyzed using an automated hemorheology analyzer. Serum levels of total cholesterol （TC）， triglycerides （TG）， low-density lipoprotein （LDL）， and high-density lipoprotein （HDL） were determined using an automated biochemical analyzer. Changes in circulating monocytes were detected by flow cytometry. Mouse bone marrow mononuclear cells were isolated in vitro and divided into blank group， model serum group， WDD-L drug-containing serum group， WDD-M drug-containing serum group， and WDD-H drug-containing serum group. CD36 expression and macrophage differentiation in each group were assessed by flow cytometry. The mechanism by which WDD mediates circulating monocyte differentiation was further explored using CD36 knockdown/overexpression RAW264.7 cell lines. ResultsCompared with the sham-operation group， the model group showed a significantly increased cardiac index （P<0.01）， significantly decreased fractional shortening （FS） （P<0.01）， and significantly increased left ventricular end-diastolic internal diameter （LVDD） and left ventricular end-systolic internal diameter （LVDS） （P<0.01）. Cardiomyocytes exhibited marked deformation and necrosis with inflammatory cell infiltration. Serum pro-BNP levels were significantly elevated （P<0.01）， and whole-blood viscosity （BV） at high， medium， and low shear rates was significantly increased （P<0.01）. Compared with the model group， the WDD groups showed significantly reduced cardiac index （P<0.05， P<0.01）， significantly increased FS （P<0.05， P<0.01）， significantly decreased LVDD and LVDS （P<0.01）， markedly improved cardiomyocyte morphology， significantly reduced inflammatory infiltration， significantly decreased serum pro-BNP levels （P<0.01）， and significantly decreased BV at high， medium， and low shear rates （P<0.01）， with the most pronounced improvement observed in the WDD-M group. Compared with the sham-operation group， TC， TG， and LDL levels were significantly increased in the model group （P<0.05， P<0.01）， while HDL levels were significantly decreased （P<0.05）. After WDD-H treatment， TC， TG， and LDL levels were significantly reduced and HDL levels were significantly increased in mice （P<0.05， P<0.01）. Compared with the sham-operation group， classical monocytes in blood and bone marrow and intermediate monocytes in blood were significantly increased in the model group （P<0.01）， whereas intermediate monocytes in bone marrow and non-classical monocytes in blood were significantly decreased （P<0.01）. After WDD administration， all circulating monocyte subsets in blood and bone marrow were significantly alleviated （P<0.05， P<0.01）， with the WDD-M group showing the optimal effect. In vitro， compared with the blank group， CD36 expression on bone marrow monocytes and the proportion of differentiated macrophages were significantly increased in the model serum group （P<0.01）， and CD36 expression was significantly upregulated on RAW264.7 cells （P<0.01）. Compared with the model serum group， all drug-containing serum groups exhibited significantly reduced CD36 expression on bone marrow monocytes and significantly reduced macrophage differentiation （P<0.01）. WDD downregulated CD36 expression in both CD36 knockdown and overexpression RAW264.7 cell lines （P<0.05， P<0.01）， with the strongest regulatory effect observed in the WDD-M drug-containing serum group. ConclusionWDD can significantly improve the manifestations of phlegm-stasis syndrome in IHD mice and reduce the proportion of classical circulating monocytes. Its mechanism may be related to the inhibition of CD36 expression on classical circulating monocytes.

Objective: o analyze the epidemic characteristics of five sexually transmitted diseases (STDs), including syphilis, gonorrhea, condyloma acuminatum, genital herpes and genital Chlamydia trachomatis infection in Yangzhou City, Jiangsu Province from 2019 to 2023, so as to provide the reference for the prevention and control strategies of STDs. Methods: Data of the onset time and diagnostic types of STDs cases in Yangzhou City from 2019 to 2023 were collected from the Infectious Disease Surveillance System of Chinese Disease Prevention and Control Information System. The temporal, regional and population characteristics of five types of STDs was analyzed using the descriptive epidemiological method. Results: A total of 10 895 cases of STDs were reported in Yangzhou City from 2019 to 2023, with an average annual reported incidence rate of 47.83/105. The average annual reported incidence rates of syphilis, gonorrhea, condyloma acuminatum, genital herpes and genital Chlamydia trachomatis infections were 41.11/105, 2.83/105, 2.59/105, 0.43/105 and 0.85/105, respectively. The reported incidence rate of STDs showed a decreasing trend from 2019 to 2023 (P<0.05), with an average annual growth rate of -3.44%. The reported incidence rates of syphilis and gonorrhea showed a decreasing trend (both P<0.05), with average annual growth rates of -4.26% and -6.47%, respectively. The reported incidence rate of genital Chlamydia trachomatis infection showed an increasing trend (P<0.05), with an average annual growth rate of 22.32%. Baoying County, Guangling District and Hanjiang District had the top three reported incidence rates of STDs, at 56.61/105, 55.61/105 and 46.50/105, respectively. The average annual reported incidence rate of STDs among males was higher than that among females (53.19/105 vs. 42.54/105, P<0.05). The STD cases were primarily people aged 50 years and above, with 6 641 cases accounting for 60.95%. The occupations of STD cases were mainly farmers, housekeepers and unemployed, with 4 670 and 3 273 cases accounting for 42.86% and 30.04%, respectively. Conclusions The overall reported incidence of STDs in Yangzhou City from 2019 to 2023 showed a downward trend, while the reported incidence of genital Chlamydia trachomatis infection showed an upward trend. The individuals aged 50 years and above, farmers, housekeepers and the unemployed were identified as high-risk groups for STDs.

With the rapid development of sequencing technologies, the detection of alternative polyadenylation (APA) in mammals has become more precise. APA precisely regulates gene expression by altering the length and position of the poly(A) tail, and is involved in various biological processes such as disease occurrence and embryonic development. The research on APA in mammals mainly focuses on the following aspects:(1) identifying APA based on transcriptome data and elucidating their characteristics; (2) investigating the relationship between APA and gene expression regulation to reveal its important role in life regulation;(3) exploring the intrinsic connections between APA and disease occurrence, embryonic development, differentiation, and other life processes to provide new perspectives and methods for disease diagnosis and treatment, as well as uncovering embryonic development regulatory mechanisms. In this review, the classification, mechanisms and functions of APA were elaborated in detail and the methods for APA identifying and APA data resources based on various transcriptome data were systematically summarized. Moreover, we epitomized and provided an outlook on research on APA, emphasizing the role of sequencing technologies in driving studies on APA in mammals. In the future, with the further development of sequencing technology, the regulatory mechanisms of APA in mammals will become clearer.

ObjectiveTo investigate the mechanism of liver injury induced by tripterygium glycosides tablets （TG） and the molecular mechanism of compound glycyrrhizin tablets （CG） in alleviating the abnormalities of cholesterol metabolism caused by TG via cholesterol metabolism. MethodsAccording to the body weights， male Sprague-Dawley （SD） rats were randomly grouped as follows： control （pure water）， low-dose TG （TG-L， 189.0 mg·kg^-1·d^-1）， high-dose TG （TG-H， 472.5 mg·kg^-1·d^-1）， TG-L+CG （189.0 mg·kg^-1·d^-1 TG + 20.25 mg·kg^-1·d^-1 CG）， and TG-H+CG （472.5 mg·kg^-1·d^-1 TG + 20.25 mg·kg^-1·d^-1 CG）， with 6 rats in each group. Rats were administrated with corresponding drugs once daily for 3 weeks. At the end of the last administration， the mRNA and protein levels of liver X receptor-alpha （LXR-α）， low-density lipoprotein receptor （LDLR）， adenosine triphosphate-binding cassette transporter A1 （ABCA1）， adenosine triphosphate-binding cassette transporter G1 （ABCG1）， 3-hydroxy-3-methylglutaryl coenzyme A reductase （HMGCR）， cholesterol 7α-hydroxylase （CYP7A1）， cholesterol 12α-hydroxylase （CYP8B1）， and sterol 27-hydroxylase （CYP27A1） in the liver tissue were determined by Real-time PCR and Western blotting， respectively. The level of 3-hydroxy-3-methylglutaryl coenzyme A reductase （HMG-CoAR）， a regulatory enzyme of cholesterol synthesis， was measured by enzyme-linked immunosorbent assay （ELISA）. HepG2 cells were used to observe the effect of TG on the cell proliferation in vitro. Specifically， HepG2 cells were grouped as follows： Low-dose TG （TG-l， 15 mg·L^-1）， medium-dose TG （TG-m， 45 mg·L^-1）， high-dose TG （TG-h， 135 mg·L^-1）， fenofibrate （FB， 10 μmol·L^-1）， CG extract， TG-h+FB （135 mg·L^-1 TG + 10 μmol·L^-1 FB）， TG-m+FB （45 mg·L^-1 TG + 10 μmol·L^-1 FB）， TG-l+FB （15 mg·L^-1 TG + 10 μmol·L^-1 FB）， TG-h+CG （135 mg·L^-1 TG + 60 μmol·L^-1 CG）， TG-m+CG （45 mg·L^-1 TG + 60 μmol·L^-1 CG）， and TG-l+CG （15 mg·L^-1 TG + 60 μmol·L^-1 CG）. The mRNA and protein levels of LXR-α， ABCG1， LDLR， CYP7A1， CYP8B1， and CYP27A1 in HepG2 cells were determined by Real-time PCR and Western blotting， respectively. ResultsThe rat experiment showed that compared with the control group， the TG-H group showed down-regulated mRNA levels of CYP7A1， CYP8B1， and CYP27A1 in the liver tissue （P<0.05， P<0.01）， which were up-regulated by the application of CG （P<0.05， P<0.01）， and the TG-H+CG group showed up-regulated mRNA level of LDLR （P<0.01）. Compared with the control group， the TG-L and TG-H groups showed down-regulated protein levels of LDLR， CYP7A1， and CYP8B1 in the liver tissue （P<0.05， P<0.01）. In addition， the protein levels of ABCG1 and LXR-α were down-regulated in the TG-H and TG-L groups， respectively （P<0.05）. Compared with TG alone， TG+CG up-regulated the protein levels of ABCG1 and LDLR （P<0.05， P<0.01）， and the protein levels of CYP7A1 and CYP8B1 in the TG-H+CG group were up-regulated （P<0.05， P<0.01）. The cell experiment showed that compared with the control group， the TG-h group presented up-regulated mRNA level of LXR-α （P<0.01）， and the TG-m and TG-h groups showcased down-regulated mRNA levels of LDLR and CYP7A1 （P<0.01） and up-regulated mRNA level of CYP27A1 （P<0.01） in HepG2 cells. The combination of CG with TG restored the above changes （P<0.01）. Western blotting results showed that compared with the control group， the TG-m and TG-h groups showed down-regulated protein levels of LXR-α， ABCG1， LDLR， CYP7A1， CYP8B1， and CYP27A1 in HepG2 cells （P<0.01）. Compared with the TG-h group， the TG-h+CG group showed up-regulated protein level of LDLR （P<0.05）. Compared with the TG-m group， the TG-m+CG group showcased up-regulated protein levels of LDLR， ABCG1， CYP7A1， and CYP27A1 （P<0.05， P<0.01）. ConclusionThe administration of TG at 189.0， 472.5 mg·kg^-1 for 3 weeks could modulate the signaling pathways associated with cholesterol efflux， endocytosis， and cholesterol biotransformation in hepatocytes， leading to the accumulation of cholesterol and subsequent liver injury in rats. CG could ameliorate the liver injury induced by lipid metabolism disorders caused by TG by up-regulating the expression of LXR-α， LDLR， ABCG1， CYP7A1， CYP8B1， and CYP27A1 to promote cholesterol biotransformation.

Background/Aims: Treatment indications for patients with chronic hepatitis B (CHB) remain contentious, particularly for patients with mild alanine aminotransferase (ALT) elevation. We aimed to evaluate treatment effects in this patient population. Methods: This rollover study extended a placebo-controlled trial that enrolled non-cirrhotic patients with CHB and ALT levels below two times the upper limit of normal. Following 3 years of randomized intervention with either tenofovir disoproxil fumarate (TDF) or placebo, participants were rolled over to open-label TDF for 3 years. Liver biopsies were performed before and after the treatment to evaluate histopathological changes. Virological, biochemical, and serological outcomes were also assessed (NCT02463019). Results: Of 146 enrolled patients (median age 47 years, 80.8% male), 123 completed the study with paired biopsies. Overall, the Ishak fibrosis score decreased in 74 (60.2%), remained unchanged in 32 (26.0%), and increased in 17 (13.8%) patients (p<0.0001). The Knodell necroinflammation score decreased in 58 (47.2%), remained unchanged in 29 (23.6%), and increased in 36 (29.3%) patients (p=0.0038). The proportion of patients with an Ishak score ≥ 3 significantly decreased from 26.8% (n=33) to 9.8% (n=12) (p=0.0002). Histological improvements were more pronounced in patients switching from placebo. Virological and biochemical outcomes also improved in placebo switchers and remained stable in patients who continued TDF. However, serum HBsAg levels did not change and no patient cleared HBsAg. Conclusions In CHB patients with minimally raised ALT, favorable histopathological, biochemical, and virological outcomes were observed following 3-year TDF treatment, for both treatment-naïve patients and those already on therapy.

Background/Aims: We investigated the clinical practice patterns of Korean endoscopists for the endoscopic resection of colorectal polyps. Methods: From September to November 2021, an online survey was conducted regarding the preferred resection methods for colorectal polyps, and responses were compared with the international guidelines. Results: Among 246 respondents, those with <4 years, 4–9 years, and ≥10 years of experiencein colonoscopy practices accounted for 25.6%, 34.1%, and 40.2% of endoscopists, respectively. The most preferred resection methods for non-pedunculated lesions were cold forceps polypectomy for ≤3 mm lesions (81.7%), cold snare polypectomy for 4–5 mm (61.0%) and 6–9 mm (43.5%) lesions, hot endoscopic mucosal resection (EMR) for 10–19 mm lesions (72.0%), precut EMR for 20–25 mm lesions (22.0%), and endoscopic submucosal dissection (ESD) for ≥26 mm lesions (29.3%). Hot EMR was favored for pedunculated lesions with a head size <20 mm and stalk size <10 mm (75.6%) and for those with a head size ≥20 mm or stalk size ≥10 mm (58.5%). For suspected superficial and deep submucosal lesions measuring 10–19 mm and ≥20 mm, ESD (26.0% and 38.6%) and surgery (36.6% and 46.3%) were preferred, respectively. The adherence rate to the guidelines ranged from 11.2% to 96.9%, depending on the size, shape, and histology of the lesions. Conclusions Adherence to the guidelines for endoscopic resection techniques varied depend-ing on the characteristics of colorectal polyps. Thus, an individualized approach is required to increase adherence to the guidelines.

In view of the few studies on the influence of Armillaria spp. infection on the content of the chemical components in different parts of Polyporus umbellatus sclerotia, this study determined the biomass of P. umbellatus sclerotia and the contents of ergosterol, polyporusterone A, polyporusterone B and polysaccharide in the separated cavity wall of the sclerotia and the uninfected part of the sclerotia in different harvesting years under the conditions of A. gallica and A. mellea infection respectively. According to the difference of content and dynamic changes of the polysaccharide and the steroid substances, the superior Armillaria sp. was screened to obtain the best harvest years of P. umbellatus. Using HPLC and UV-VIS spectrophotometry methods, the contents of ergosterol, polyporusterone A, polyporusterone B and polysaccharide in P. umbellatus sclerotia infected by the two Armillaria spp. in different years were determined. In addition, the differentially expressed genes related to P. umbellatus polysaccharide synthesis were screened according to the transcriptomic data of different parts of P. umbellatus after A. mellea infection. With the increase of years, the biomass of sclerotia infected by different Armillaria spp. had significant differences, and there were significant differences in the four components of sclerotia. The four components of the separated cavity wall of the sclerotia were significantly higher than those of the uninfected part. The best harvest time was the third year after cultivation. Transcriptomic analysis showed that the infection of Armillaria spp. could significantly promote polysaccharide synthesis, which provided a basis for polysaccharide content determination at the molecular level. The study clarified the influence of different Armillaria spp. infection on the accumulation of chemical components of P. umbellatus sclerotia, laying a foundation for exploring the symbiosis mechanism and provided a scientific clue for screening superior Armillaria sp. and guiding the artificial cultivation of P. umbellatus sclerotia.

Yunnan Province borders with Myanmar, Vietnam, and Laos, the China-Myanmar border area is the key area for prevention of re-establishment from imported malaria after the disease was eliminated in China. Since the malaria elimination action plan was launched in Yunnan Province in 2011, 129 counties (cities, districts) were classified into three categories according to malaria incidence and transmission risk, and different technical strategies and measures were implemented with adaptations to local circumstances. A total of 68 malaria consultation service stations were established on the Chinese side of the China-Myanmar border and 80 malaria prevention and control stations were established on the Myanmar side by Yunnan Province in 2014. Then, the “Three Lines of Defense” strategy was implemented for malaria elimination in the China-Myanmar border area in Yunnan Province during the period from 2015 to 2018, and this strategy was further refined and adjusted to the “3 + 1” strategy for prevention of re-establishment from imported malaria in 2019. Through decades of multifaceted efforts, the malaria elimination goal was achieved in Yunnan Province in June 2021. However, the number of imported malaria cases appeared a tendency towards a rise in Yunnan Province in 2023 and 2024, due to changes in the situation in Myanmar and the gradual resumption of international travel and border crossings following the adjustment of the COVID-19 prevention and control policy in China. The joint malaria prevention and control cooperation between China and Myanmar was initiated with the pilot project for joint malaria prevention and control in the China-Myanmar border area in 2005, and this project was progressed into the joint malaria and dengue fever prevention and control project in parts of the Greater Mekong Subregion border areas in 2010. The threat of overseas malaria epidemics to border areas in Yunnan Province was effectively reduced through implementation of coordination meetings with Myanmar health departments, establishment of efficient information exchange mechanisms, establishment of overseas surveillance sentinel sites, technical training, provision of material supports, joint propagation activities and joint responses to malaria epidemics. This project was incorporated into the Five-Year Plan of Action on Lancang-Mekong Cooperation (2018—2022) in China in 2018, with 5 liaison offices and 20 liaison workstations established in Myanmar, Laos, Vietnam, Cambodia, and Thailand, and 21 cross-border malaria surveillance sites assigned in border areas of Myanmar, Laos and Vietnam, and a long-term malaria prevention and control cooperation mechanisms was established through meetings, training, propagation, and joint investigations. Currently, Yunnan Province is poised to engage in more extensive and in-depth cooperation with neighboring countries, including malaria diagnosis and treatment techniques, drug and vaccine research and development, talent cultivation, information sharing, cross-border human health services, and health promotion, under the guidance of the Five-Year Plan of Action on Lancang-Mekong Cooperation (2023—2027).

ObjectiveThis study leverages structural data from antigen-antibody complexes of the influenza A virus neuraminidase (NA) protein to investigate the spatial recognition relationship between the antigenic epitopes and antibody paratopes. MethodsStructural data on NA protein antigen-antibody complexes were comprehensively collected from the SAbDab database, and processed to obtain the amino acid sequences and spatial distribution information on antigenic epitopes and corresponding antibody paratopes. Statistical analysis was conducted on the antibody sequences, frequency of use of genes, amino acid preferences, and the lengths of complementarity determining regions (CDR). Epitope hotspots for antibody binding were analyzed, and the spatial structural similarity of antibody paratopes was calculated and subjected to clustering, which allowed for a comprehensively exploration of the spatial recognition relationship between antigenic epitopes and antibodies. The specificity of antibodies targeting different antigenic epitope clusters was further validated through bio-layer interferometry (BLI) experiments. ResultsThe collected data revealed that the antigen-antibody complex structure data of influenza A virus NA protein in SAbDab database were mainly from H3N2, H7N9 and H1N1 subtypes. The hotspot regions of antigen epitopes were primarily located around the catalytic active site. The antibodies used for structural analysis were primarily derived from human and murine sources. Among murine antibodies, the most frequently used V-J gene combination was IGHV1-12*01/IGHJ2*01, while for human antibodies, the most common combination was IGHV1-69*01/IGHJ6*01. There were significant differences in the lengths and usage preferences of heavy chain CDR amino acids between antibodies that bind within the catalytic active site and those that bind to regions outside the catalytic active site. The results revealed that structurally similar antibodies could recognize the same epitopes, indicating a specific spatial recognition between antibody and antigen epitopes. Structural overlap in the binding regions was observed for antibodies with similar paratope structures, and the competitive binding of these antibodies to the epitope was confirmed through BLI experiments. ConclusionThe antigen epitopes of NA protein mainly ditributed around the catalytic active site and its surrounding loops. Spatial complementarity and electrostatic interactions play crucial roles in the recognition and binding of antibodies to antigenic epitopes in the catalytic region. There existed a spatial recognition relationship between antigens and antibodies that was independent of the uniqueness of antibody sequences, which means that antibodies with different sequences could potentially form similar local spatial structures and recognize the same epitopes.