OBJECTIVE To understand the drug resistance,serotypes,virulence-associated genes and epidemiologi-cal characteristics of group B Streptococcus(GBS)isolated from puerpera in this area so as to provide bases for prevention of mother-to-infant infections.METHODS Totally 67 strains of GBS were isolated from obstetrics out-patient department of The First Affiliated Hospital of Nanchang University from Jan.2023 to Dec.2023.The spe-cies of the strains were identified by VITEK MS,the drug susceptibility testing was carried out by disc diffu-sion method.Multilocus sequencing types,capsular types,virulence genes and drug resistance genes were analyzed by means of whole genome sequencing technique.RESULTS The 67 strains of GBS were sensitive to penicillin,vancomycin,ceftriaxone and linezolid;the drug resistance rates to erythromycin and clindamycin were 76.12％and 55.22％,respectively.All strains fell into 7 serotypes,with serotype V predominant;21 sequence types were in-volved,with ST529 most prevalent;8 clonal complexes(CCs)were involved,with CC12 most common.Totally 17 types of drug resistance genes were identified,and the carrying rate of macrolide resistance gene ErmB was highest.Among all the virulence genes except for the adhesion genes fbsA and fbsB,the carrying rates of 18 genes involving in invasion,adhesion,and immune evasion-associated virulence genes were more than 86.57％;67.16％of the strains co-expressed both PI-1 and PI-2a pilus islands.CONCLUSIONS The drug resistance rate of the GBS strains isolated from the puerpera is high,and the strains carry multiple drug resistance genes and viru-lence genes and present with molecular clonal diversity.The serotype V/ST529 is the predominant clone,for which the prevention and control should be strengthened.

OBJECTIVE To understand the drug resistance,serotypes,virulence-associated genes and epidemiologi-cal characteristics of group B Streptococcus(GBS)isolated from puerpera in this area so as to provide bases for prevention of mother-to-infant infections.METHODS Totally 67 strains of GBS were isolated from obstetrics out-patient department of The First Affiliated Hospital of Nanchang University from Jan.2023 to Dec.2023.The spe-cies of the strains were identified by VITEK MS,the drug susceptibility testing was carried out by disc diffu-sion method.Multilocus sequencing types,capsular types,virulence genes and drug resistance genes were analyzed by means of whole genome sequencing technique.RESULTS The 67 strains of GBS were sensitive to penicillin,vancomycin,ceftriaxone and linezolid;the drug resistance rates to erythromycin and clindamycin were 76.12％and 55.22％,respectively.All strains fell into 7 serotypes,with serotype V predominant;21 sequence types were in-volved,with ST529 most prevalent;8 clonal complexes(CCs)were involved,with CC12 most common.Totally 17 types of drug resistance genes were identified,and the carrying rate of macrolide resistance gene ErmB was highest.Among all the virulence genes except for the adhesion genes fbsA and fbsB,the carrying rates of 18 genes involving in invasion,adhesion,and immune evasion-associated virulence genes were more than 86.57％;67.16％of the strains co-expressed both PI-1 and PI-2a pilus islands.CONCLUSIONS The drug resistance rate of the GBS strains isolated from the puerpera is high,and the strains carry multiple drug resistance genes and viru-lence genes and present with molecular clonal diversity.The serotype V/ST529 is the predominant clone,for which the prevention and control should be strengthened.

【Objective】 To evaluate the effect of Arntl on T cell development and T cell-mediated anti-viral immunity. 【Methods】 Arntl^F/FCD4cre⁺(KO) in mice was constructed to delete Arntl gene specifically in T cells. We examined the percentage and number of T cell subsets in the thymus and spleen by flow cytometry (FCM). At day 8 after lymphocytic choriomeningitis virus (LCMV) infection, the proportions of T cell subsets, virus-specific CD8⁺ T cells and IFN-γ secreting T cells were analyzed. The viral load in the spleen was measured using qPCR. Naive CD4⁺ T cells (CD4⁺CD25^-CD44^-CD62L⁺) were sorted by flow cytometry to perform T helper cell differentiation in vitro. 【Results】 The percentage and number of T cells in the thymus and spleen of KO mice showed no significant change compared with those in the control group (Arntl^F/FCD4cre^- mice, WT) (P>0.05). Acute LCMV infection did not cause observable changes in effector T cell proportion in the spleen of KO mice compared to that in WT mice (P>0.05), but KO mice showed a higher proportion of IFN-γ secreting T cells (P<0.05) and better virus clearance (P<0.05). In addition, naive CD4⁺ T cells from KO mice were more prone to differentiate into Th1 cells in vitro (P<0.05). 【Conclusion】 Arntl deletion in T cells does not affect T cell development, but enhances their ability to defend against viral infection by promoting Th1 cell differentiation and response.

Objective To explore the effect of collagen membrane combined with recombinant human bone morphogenetic protein-2(rhBMP-2) on periodontal tissue regeneration and repair in periodontal defect models of rats.Methods Eighteen male healthy Wistar rats,which were made experimental periodontal bone defects in the inferior incisors,were randomly divided into three groups:control group,collagen membrane group(Co),collagen membrane and rhBMP-2 group(Co/rhBMP-2).Two rats from each group were sacrificed at 4,6,8 weeks after operation.The mandibles were removed,and examined under light microscope.Results In Co/rhBMP-2 group: 4 weeks after operation,a large amount of bone formed in the defects;6 weeks later,new bone filled in the defects;8 weeks later,alveolar bone emerged,newly-formed periodontal ligament and cementum localized at the root edges,no gingival epithelium was observed.In Co group:4 weeks after operation,new bone formed at the edge of the defects;6 weeks later,a larger amount of bone and periost were observed;8 weeks later,a small amount of periodontal ligament and cementum localized at the root edges.In control group: 4 weeks after operation,there was a small amount of newly-formed bone at the edge of the defects;6 weeks later,collagen fibers were found at the edge of defects;8 weeks later,a small amount of periodontal tissue reached its original height and gingival epithelium proliferated obviously.Conclusion Collagen membrane combined with rhBMP-2 which has not only conductive effect but also effect of osteoinduction,can prevent the long-epithelium growing,maintain the growth gap,and promote periodontal tissue to regenerate.