Oral somatic transgene vaccination using attenuated S. typhimurium

Area of Science:

• * Microbiology and Immunology
• * Genetic Engineering and Vaccine Development

Background:

• * Development of novel oral genetic immunization strategies is crucial for effective vaccine delivery.
• * Attenuated bacterial strains offer potential as vectors for delivering foreign antigens.

Purpose of the Study:

• * To evaluate an attenuated strain of Salmonella typhimurium (S. typhimurium) as a vehicle for oral genetic immunization.
• * To assess the immunogenicity and protective efficacy of transformants expressing Listeria monocytogenes virulence factors (ActA and listeriolysin).

Main Methods:

• * Construction of eukaryotic expression vectors with truncated ActA and listeriolysin genes.
• * Transformation of S. typhimurium aroA with these vectors.
• * Oral immunization of animals with the transformed S. typhimurium and assessment of cellular and humoral immune responses.
• * In vitro studies to demonstrate plasmid DNA transfer to host cells (primary peritoneal macrophages).

Main Results:

• * Oral immunization with transformants induced robust cellular and humoral immune responses.
• * Listeriolysin transformants conferred protective immunity.
• * Evidence of plasmid DNA transfer from the bacterial carrier to host cells was observed.
• * The system proved versatile for antigen delivery and antibody generation.

Conclusions:

• * Attenuated S. typhimurium is a highly effective vehicle for oral genetic immunization.
• * This approach enables the identification of protective antigens and efficient antibody generation against various DNA segments.
• * The demonstrated plasmid transfer mechanism supports the efficacy of this immunization system.