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Brucellosis is the most common zoonotic bacterial disease. Prevention of human brucellosis is achieved through pasteurization of dairy products, appropriate sanitation and vaccination of domestic animals against the Brucella species. B. abortus unlipidated 19 kDa outer membrane protein (U-Omp19) is a promising candidate for a subunit vaccine against brucellosis. This study investigates immunogenicity of Omp19 alone and with Freund's adjuvant (Omp19-IFA) and N-trimethyl chitosan (TMC/Omp19) nanoparticles, as well as the effect of Omp19 administration route on immunological responses and protection. The omp19 gene was expressed in E. coli BL21 (DE3). After purification, the recombinant Omp19 was loaded onto TMC nanoparticles by ionic gelation with tripolyphosphate. Particle size and loading efficiency of the nanoparticles were determined. Omp19-IFA was administered intraperitoneally while TMC/Omp19 nanoparticles were administered orally and intraperitoneally. The results indicated that intraperitoneal (i.p.) immunization by Omp19-IFA and TMC/Omp19 nanoparticles induced Th1 and Th2 immune responses, respectively, whereas oral immunization of TMC/Omp19 nanoparticles induced a mixed Th1/Th17 immune response. Moreover, oral immunization increased IgA levels in feces. Immunized mice were challenged with virulent B. melitensis 16 M and B. abortus 544. Oral immunization with TMC/Omp19 nanoparticles induced a remarkably high protection level against B. melitensis and B. abortus. The results showed that immunization route has a pivotal role in immune response polarization and protective efficiency of Omp19 antigen. Also, it was deduced that the higher protection level achieved through oral administration of TMC/Omp19 nanoparticles may be due to the elicited Th17 response.

A new modified carbon paste electrode (CPE) based on a recently synthesized ligand [2-mercapto-5-(3-nitrophenyl)-1,3,4-thiadiazole] (MNT), self-assembled to gold nanoparticles (GNP) as suitable carrier for Cd(II) ion with potentiometric method are described. The proposed electrode exhibits a Nernstian slope of 29.4 AE 1.0 mV per decade for Cd(II) ion over a wide concentration range from 3.1 Â 10 À8 to 3.1 Â 10 À4 mol L À1 . The detection limit of electrode was 2.0 Â 10 À8 mol L À1 of cadmium ion. The potentiometric responses of electrode based on MNT is independent of the pH of test solution in the pH range 2.0 -4.0. It has quick response with response time of about 6 s. The proposed electrode show fairly good selectivity over some alkali, alkaline earth, transition and heavy metal ions. Finally, the proposed electrode was successfully employed to detect Cd(II) ion in hair and water samples.

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