Characterization of a Salmonella Typhimurium ghost carrying an adjuvant protein as a vaccine candidate for the protection of chickens against virulent challenge.

In this study we describe the generation of a safe, immunogenic, genetically inactivated Salmonella Typhimurium ghost vaccine candidate carrying the Escherichia coli heat-labile enterotoxin B subunit (LTB) protein as an adjuvant molecule. An asd+ p15A ori- plasmid pJHL187-LTB harboring the E lysis gene cassette and a foreign antigen delivery cassette containing the eltB gene was used to transform a Δasd Salmonella Typhimurium (JOL1311) strain to construct the ghost strain, JOL1499. Incubation of mid-logarithmic phase grown JOL1499 cultures at 42°C resulted in co-expression of the eltB and E lysis genes, leading to the generation of Salmonella Typhimurium ghost cells carrying the LTB protein (Salmonella Typhimurium-LTB ghost). The production of LTB in Salmonella Typhimurium-LTB ghost preparations was confirmed by Western blot analysis and functional activity of the LTB protein to bind with GM1 receptors was determined by means of GM1 ELISA. Efficacy of the Salmonella Typhimurium-LTB ghost as a vaccine candidate was evaluated in a chicken model using 56 five-week-old chickens, which were divided into four groups (n = 14); Group A was designated as the non-vaccinated control group, whereas the birds in groups B, C, and D were intramuscularly immunized with 10(9), 10(8), and 10(7) ghost cells, respectively. Compared with the non-immunized chickens (group A), immunized chickens (groups B, C and D) exhibited increased titers of plasma IgG and intestinal secretory IgA antibodies. ...
Source: Avian Pathology - Category: Pathology Authors: Tags: Avian Pathol Source Type: research