Immunization with Salmonella Abortusequi phage lysate protects guinea pig against the virulent challenge of SAE-742.

The researchers explored the possibility of creating a protective agent against Salmonella Abortusequi, a bacteria causing serious diseases in horses, with the help of a bacteriophage P-SAE-2. The study demonstrated that both plain and enhanced with aluminum hydroxide gel phage lysates can provoke an immune response and protect guinea pigs against a following challenge with a potent strain of the bacteria.

Research Context

• Salmonella Abortusequi is a harmful bacterium causing serious illnesses in horses, potentially resulting in loss of foetus in infected animals.
• Immunoprophylactic methods for combating this bacterium in horses are in need of development and improvement.
• In this context, the researchers investigated the potential of using a broad host range bacteriophage P-SAE-2 to create a protective agent that can boost the immune response of the host organism and protect it against a potent strain of Salmonella Abortusequi.

Methodology

• The study used Guinea pigs as their model organism for developing and testing the protective agent.
• The team used bacteriophage P-SAE-2 to create lysates, which are solutions containing decomposed cells.
• These lysates were then either used plain or enhanced with an adjuvant, aluminum hydroxide gel, that is known to increase the immune response.
• Three batches of lysates were created, each through separate cycles, and after characterization, pooled together for the immunization study.

Findings

• Both plain and adjuvanted phage lysate preparations evoked both humoral (involving antibodies in the blood and lymph) and cell-mediated immunity (where the destruction of pathogens is mediated by certain white blood cells).
• A dose of 50 µl of the adjuvanted lysate seemed to have elicited the best protective response in guinea pigs, showing high efficacy against a direct challenge with a virulent strain of Salmonella Abortusequi at 28 days post-immunization.

Conclusion and Significance

• The study demonstrated a new method of bacterial inactivation to produce better and safer immunoprophylactic agents.
• This research is the first instance of creating an inactivated vaccine candidate using bacteriophage lysates against equine salmonellosis, offering a novel approach in tackling this serious disease in horses.