Novel approach of vaccination against Brucella abortus 544 based on a combination of fusion proteins, human serum albumin and brucella abortus Lipopolysaccharides.

Lipopolysaccharide (LPS) of Brucella abortus is an essential component for developing the subunit vaccine against brucellosis. B. abortus LPS was extracted by n-butanol, purified by ultracentrifugation and detoxified by alkaline treatment. Pyrogenicity and toxicity of B. abortus LPS and detoxified–LPS (D-LPS) were analyzed and compared with LPS of E. coli. Different groups of mice were immunized intraperitoneally with purified B. abortus LPS, D-LPS, a combination of LPS with human serum albumin (LPS-HSA) and B. abortus S19 bacteria; besides, control mice were inoculated with sterile saline. Two doses of vaccine were given 4 weeks apart. Mice were challenged intraperitoneally with virulent B. abortus 544 strain 4 weeks after the second dose of vaccine. Sera and spleens of mice were harvested 4 weeks after challenge. LPS-B. abortus was 10,000-fold less potent in LAL test and 100-fold less potent in eliciting fever in rabbits than in E. coli LPS. And D-LPS was very less potent in LAL test and eliciting fever in rabbits ordinary LPS. The antibody titer of anti-LPS immunoglobulin G (IgG) was higher than D-LPS. However, mice immunized with either LPS, D-LPS or LPS-HSA vaccines showed a significant protection against infection of the spleen (p<0.01). There was no significant difference between mice immunized with LPS and D-LPS in terms of protection (p<0.99). Therefore, it was concluded that D-LPS and LPS-HSA for B. abortus can be used as safer and more potent vaccines than ordinary LPS-B. abortus vaccine

Optimized antibacterial measures against Escherichia coli O157:H7 and Staphylococcus aureus

Varied mixtures of different concentrations 1, 1.5 and 2% of acetic (AA), lactic (LA), propionic (PA) and formic (FA) acids at 1:1 ratio were spray-washed on inoculated meat to evaluate their efficacy in reducing loads of Escherichia coli O157:H7 andStaphylococcus aureus on meat tissue. It was found that increasing the concentration of the used organic acids increased the bacterial lethality proportionally. And significant difference (P<0.05) was observed in the lethal effect of different mixtures and concentrations of the used organic acids. As a novel combination, FA treatments as combinations with AA, LA, and PA, especially FA with LA, reduced bacterial loads greatly, up to 3 logs cfu/ml and eradicated inoculated bacteria, E. coli O157:H7 and S. aureuscompletely within 3-6 days. This reduction was higher than that incurred by other combinations. Significantly, higher log reductions by the used organic acids were obtained for S. aureus than for E. coli O157:H7. It was concluded that the combination of LA and FA treatment was a highly promising, feasible, and economical method of decontaminating meat surface from both E. coli O157:H7 and S. aureus bacteria. Moreover, it is safe if compared with other approaches