ABSTRACT
Our studies tried to demonstrate Eha (Et haemolysin activator) could regulate the resistance of the bacterium against acidification to survive in the macrophage and explain its underlying molecular mechanism.When the bacteria infected the macrophages at time intervals,intracellular survival rate in bafilomycin-treated macrophages was higher than that with untreated cells,and the rate of wild type ET 13 was higher than that of its eha mutant,respectively (P＜0.05).The survival rate of the wild type was higher than that of the mutant under acid treatment (P＜0.05).To determine the conditions that induced the highest eha expression,we constructed a pMP220-Peha LacZ plasmid and determined the lacZ expression under different conditions.After exposure of pH6.3 medium for 2 h time,we performed the whole transcriptomic profiles of the wild type and mutant by RNA-sequencing.We identified 147 differentially-expressed genes ([log2 ratio| ≥1),113 and 34 of which were significantly up-and down-regulated,respectively in the mutant,comparing with the wild type.These findings were validated by qRT-PCR.GO functional analysis revealed that these genes were divided into 25 categories,including the bacterial catalysis,cellular composition,combination,localization,metabolism,processing,and transportation.Based on the KEGG database,these genes were distributed in 55 pathways,such as two-component system,ABC transporters,and microbial metabolism in diverse environments.Overall,Eha is an important regulator to affect all kinds of target genes and pathways for E.tarda to adapt to an acid environment.These results could be helpful for further investigations of the mechanisms by which E.tarda survives in macrophages.
ABSTRACT
Objective:Preparation and immune characteristic analysis of polyclonal antibody against hypervariable region protein of Taura syndrome virus major capsid protein VP 1 as a reference for studies on immunological diagnosis reagent.Methods:The recombinant vector pET-VP1 was transformed into E.coli BL21 for protein expression.Immunizing a New Zealand rabbit with purified VP1 protein,the titer of anti-VP1 serum was determined by Agar diffusion test and ELISA.Monoclonal phage specific binding to the purified VP1 protein was used for competitive inhibition test.Results: The VP1 protein was soluble and high expression in E.coli BL21.The biological activity titer of anti-VP1 serum reached 1∶26 ,1∶217 determined by Agar diffusion test and ELISA respectively.A litter binding activity of antiserum and VP 1 protein could be blocked by monoclonal phage , but would not affect the final positive result.Conclusion:High titer antibody Preparation of the VP 1 hypervariable region protein.The binding activity of the polyclonal antibody with VP1 protein was not affected by the mutations of VP 1 protein in minority areas ,so the antiserum could be used as immu-nological detection diagnosis agent.
ABSTRACT
Streptococcus suis is a swine pathogen and also a zoonotic agent. The formation of biofilms allows S. suis to become persistent colonizers and resist clearance by the host immune system and antibiotics. In this study, biofilm forming potentials of various S. suis strains were characterized by confocal laser scanning microscopy (CLSM), scanning electron microscopy (SEM) and tissue culture plates stained with crystal violet. In addition, the effects of five antimicrobial agents on biofilm formation were assayed in this study. S. suis produced biofilms on smooth and rough surface. The nutritional contents including glucose and NaCl in the growth medium modulated biofilm formation. There was a significant difference in their biofilm-forming ability among all 46 S. suis strains. The biofilm-forming potential of S. suis serotype 9 was stronger than type 2 and all other types. However, biofilm formation was inhibited by five commonly used antimicrobial agents, penicillin, erythromycin, azithromycin, ciprofloxacin, and ofloxacin at subinhibitory concentrations, among which inhibition of ciprofloxacin and ofloxacin was stronger than that of other three antimicrobial agents.Our study provides a detailed analysis of biofilm formation potential in S. suis, which is a step towards understanding its role in pathogenesis, and eventually lead to a better understanding of how to eradicate S. suis growing as biofilms with antibiotic therapy.
Subject(s)
Humans , Animals , Anti-Bacterial Agents/analysis , Biofilms , Immune System , Immunocompromised Host , Microscopy, Electron, Scanning/methods , Drug Resistance, Microbial/genetics , Swine , Streptococcus suis/genetics , Streptococcus suis/isolation & purification , Methods , Sus scrofa , VirulenceABSTRACT
A new method agar diffsive hemolysis test (ADHT)was esteblished to measure thd hemlytic titer of HEC toxin produced by Aeromonas hydrophila. The ADHT had also been compared with the spectrophotometry and the microhemolyses test The results shows that the hemlytic titer detected by ADHTwas hither than the former methods and the ADHT was cha ractered by better and more easily determined.
ABSTRACT
A new method agar diffsive hemolysis test (ADHT)was esteblished to measure thd hemlytic titer of HEC toxin produced by Aeromonas hydrophila.The ADHT had also been compared with the spectrophotometry and the microhemolyses test The results shows that the hemlytic titer detected by ADHTwas hither than the former methods and the ADHT was charactered by better and more easily determined.
ABSTRACT
A new method skim milk proteolysis ager diffusion test (SMPAD) was established. Extracelluar proteases in supernatants produced by Aeromonas hydrophila J-l in different mediums were detected by SMPAD and the Azocasein substrat method. It was demonstrated that the two methods agreed with each other and the SMPAD test was charactered by more easily operated, more sensitive and better repeated.
ABSTRACT
Objective:To study the antigenicity of OMP extracted from Edwardsiella tarda.Methods:ELISA, Bactericidal test, Agglutinating test and Western blotting were used for testing the antigenic titers and immunogenicity of OMP.Results:In immunoblotting, by using ATCC15947 OMP antibody, the non pathgenic strains were negative, while all pathogenic strains except Et 122 gave positive results and had OMP bands of 33k, 35k, 38k, and 45k. OMPs of both ATCC 15947 and JEL4 could induce high antibody titers. Further more, the antibodies evoked by OMPs of ATCC 15947 of 33k or 35k could also protected mice to some degree when diluted.Conclusion:The 33k, 35k, 38k, and 45k of OMPs may be protective antigens, and the OMPs of Et could be a candidative component for vaccine.