Recombinant N-terminal outer membrane porin (OprF) of Pseudomonas aeruginosa is a promising vaccine candidate against both P. aeruginosa and some strains of Acinetobacter baumannii.

Pseudomonas aeruginosa is an evolving pathogen which can cause serious infections especially to immunocompromised patients. Its high resistance profile to antibiotics results in difficulty, and sometimes impossibility, in treating afflicted patients. Developing an effective vaccine against P. aeruginosa is an important approach to tackle this problem. A similar problematic situation exists for Acinetobacter baumannii. Several vaccine candidates have been investigated up till now but still there is no approved vaccine in the market. One important antigen of P. aeruginosa is the outer membrane protein F (OprF) which functions as a porin with relevant important roles in virulence. Previous studies focused mainly on the C-terminal peptidoglycan binding domain of OprF as a vaccine candidate. In the current study, we have investigated the N-terminal porin domain of OprF as a potential vaccine candidate against P. aeruginosa. Histidine-tagged recombinant N-terminal OprF (amino acid range 25-200; OprF25-200) was overexpressed in Escherichia coli and purified using metal affinity chromatography. Swiss albino mice were immunized with OprF25-200 adjuvanted with Bacillus Calmette-Guérin (BCG) and alum and the immune response was evaluated. Immunized mice developed antigen-specific IgG1 and IgG2a and were protected against challenge by both P. aeruginosa and a clinical isolate of A. baumannii expressing OprF. Serum from OprF25-200-immunized mice showed cross-reactivity with both pathogens using western blotting and whole cell enzyme-linked immunosorbent assay (ELISA). To our knowledge, this is the first report to demonstrate that the N-terminal domain of OprF is sufficiently immunogenic to protect against the two pathogens.

The Enhancement of the Pasteurella's Bacterin by Propolis Extracts.

BACKGROUND: Pasteurella multocida continues to pose a danger to prone farm and wild animals all over the world. Chemotherapeutic treatments are progressively losing their effectiveness, last for long time, and cost a lot of money, as well as being toxic to human consumers. Therefore, clearing the way for immunization as a big-wheel alternative against the economic grain. Yet, the vaccines available in the market do not confer the necessary protection against the pathogen. The integration of the well adjuvanted killed vaccine with the attenuated vaccines proved to offer an effective protection to the host animals. However, the bare use of the killed bacterin to provide protection from the possible harm of the live attenuated vaccine was doubtful. METHODS: In the present study, propolis extracts were used to ameliorate the immunogenicity of the Pasteurella bacterin. The cellular and humoral activities were assessed for the different bacterin formulations. RESULTS: Propolis extracts adjuvants proved to broaden and extend the IgG potency, as well as to induce a unique mucosal protection against the bacterium. Simultaneously it offered an anti-inflammatory effect that increased the tolerability to the bacterin. While the cellular activity was relatively reduced with propolis extracts. CONCLUSION: These results confirm the effectiveness of the formulation of the bacterin with propolis to offer a potent homologous primary protection to the animals against the long-life use of the attenuated Pasteurella vaccines.