Spotted fever group Rickettsia(SFGR)are gram-negative,obligate intracellular pathogens that cause spotted fever rickettsiosis,a zoonotic disease.SFGR invade host cells through the expression of outer membrane proteins and Anaplasma-derived proteins.Then they use virulence factors,including phospholipases and cell surface antigens,to evade or suppress host immune de-fenses,thereby facilitating host colonization and intercellular dissemination,and exerting pathogenic effects.This review summarizes current research progress in various SFGR virulence factors,to further elucidate the pathogenic mechanisms of spotted fever rickettsio-sis,and provide a reference for the prevention and treatment of this disease.

Objective : To investigate whole genome information of a newly isolatedBifidobacterium animalissubsp. lactic B4 strain from healthy human feces was analyzed and its probiotic properties. Methods : The antimicrobial resistance, hemolytic, gastric acid tolerance and biochemical characteristics of B. animalis B4 were evaluated byin vitroexperiments, and its whole genome was sequentially sequenced and functional annotation was performed by next and three-generation sequencing technology. Results: Whole genome sequencing of B. animalis B4 showed that its genome size was 1 944 146 bp, with GC content of 60.49%, no plasmid, and a total of 1 642 genes. The results ofin vitroanalysis showed that the B. animalis B4 had good probiotic properties, including non-hemolytic and stomach acid resistance. At the same time, the genome results showed that the B. animalis B4 strain did not have toxin and disease-related genes, drug resistance genes were few and the transmission ability was not high, so it had high safety. Gene annotation of KEGG, COG and GO showed that it contained many biological active enzymes, such as β-galactosidase, L-lactate dehydrogenase and other probiotic genes. Conclusion The B. animalis B4 has good probiotic properties, showing excellent safety at the genetic level, with a probiotic gene sequence.

Spotted fever group Rickettsia(SFGR)are gram-negative,obligate intracellular pathogens that cause spotted fever rickettsiosis,a zoonotic disease.SFGR invade host cells through the expression of outer membrane proteins and Anaplasma-derived proteins.Then they use virulence factors,including phospholipases and cell surface antigens,to evade or suppress host immune de-fenses,thereby facilitating host colonization and intercellular dissemination,and exerting pathogenic effects.This review summarizes current research progress in various SFGR virulence factors,to further elucidate the pathogenic mechanisms of spotted fever rickettsio-sis,and provide a reference for the prevention and treatment of this disease.

Objective: Balb/c mice infected with respiratory syncytial virus(RSV) were used to investigate the metabolic changes in cecal luminal content. Methods: A total of 13 female Balb/c mice were randomly divided into Case group(n=7) and control(Ctrl) group(n=6). Animals in Case group were infected with RSV by using intranasal method, while mice in Ctrl group were treated with DMEM medium. Mice were anesthetized with intraperitoneal administration of 10% chloral hydrate and the cecal luminal contents were harvested under sterile conditions. Metabolite concentrations were measured by UPLC-QTOF/MS system. Univariate and multivariate statistical analysis were used to identify differential metabolites between Case and Ctrl groups. Results: The overall base peak chromatogram between Case and Ctrl groups had a clear disparity, and PCA and OPLS-DA analysis showed obviously discrepancy based overall metabolomic profile. L-serine, 2-ketobutyric acid, Oleic acid and Chenodeoxycholic acid glycine conjugate were enriched in Case group, whereas L-methionine, L-tyrosine and Nicotinic acid were depleted. Pathway analysis showed lysine degradation, Cysteine and methionine metabolism were enriched. Conclusion Lung injury induced by RSV infection may cause the endogenous metabolism disorder of cecal contents.