Salmonella Pullorum lacking srfA is attenuated, immunogenic and protective in chickens

Area of Science:

• Veterinary Microbiology
• Immunology
• Vaccine Development

Background:

• Salmonella Pullorum poses a significant economic threat to poultry industries, particularly in developing nations.
• Effective vaccines are crucial for controlling and eradicating Salmonella Pullorum prevalence.

Purpose of the Study:

• To construct and evaluate a live attenuated vaccine candidate for Salmonella Pullorum.
• To assess the biological characteristics and protective efficacy of a srfA deletion mutant (C79-13ΔsrfA).

Main Methods:

• Construction of a srfA deletion mutant (C79-13ΔsrfA) from Salmonella Pullorum strain C79-13.
• Evaluation of the mutant's virulence, immunogenicity, and protective efficacy in one-day-old HY-line white chickens via oral immunization.
• Challenge studies using Salmonella Pullorum strain C79-13 and Salmonella Gallinarum strain SG9 post-immunization.

Main Results:

• The C79-13ΔsrfA mutant exhibited significantly reduced virulence compared to the parental strain C79-13.
• Oral immunization with C79-13ΔsrfA induced robust humoral and cellular immune responses.
• Vaccinated chickens showed 90% and 80% survival rates against Salmonella Pullorum and Salmonella Gallinarum challenges, respectively.
• Growth performance in vaccinated chickens was comparable to unvaccinated controls.

Conclusions:

• The srfA deletion mutant (C79-13ΔsrfA) is a promising live attenuated vaccine candidate against Salmonella Pullorum.
• The developed vaccine effectively protects chickens against homologous and heterologous Salmonella challenges.
• This attenuated strain offers a potential solution for controlling economic losses due to Salmonella infections in poultry.