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Behaviour of S. paratyphi A in mice immunized with homologous and heterologous bacterial proteins
Abstract:
Mice immunized with proteins from S. typhimurium and from S. paratyphi C resisted the toxicity of a concentration of S. paratyphi A which killed the controls; this is in contrast to the results found in mice immunized with the same amount of proteins from the homologous S. paratyphi A. For the neutralization of the S. paratyphi A toxicity a higher quantity of homologous proteins was necessary in the immunizations. It is assumed that either S. paratyphi A synthesizes--on artificial media--a small amount of proteins responsible for the induction of neutralizing antibodies or that it is an intrinsic weak immunogen. In the sera of mice in which sufficient neutralizing antibodies were induced, the proteins of S. paratyphi A cross-reacted in agar-gel, with the proteins from S. typhimurium and from S. paratyphi C.
Insights
Immunizing mice with Salmonella typhimurium and S. paratyphi C proteins protected against S. paratyphi A toxicity. Higher homologous S. paratyphi A protein doses were needed for neutralization, suggesting S. paratyphi A is a weak immunogen.
Area of Science:
- Immunology
- Microbiology
- Bacteriology
Background:
- Salmonella species are significant bacterial pathogens.
- Understanding immune responses to Salmonella serotypes is crucial for vaccine development.
- Cross-reactivity between different Salmonella serotypes can influence vaccine efficacy.
Purpose of the Study:
- To investigate the immunogenicity and cross-protective potential of Salmonella proteins against S. paratyphi A toxicity.
- To determine the quantity of homologous proteins required for neutralizing S. paratyphi A toxicity.
- To explore the antigenic relationship between S. paratyphi A, S. typhimurium, and S. paratyphi C.
Main Methods:
- Mice were immunized with proteins from S. typhimurium, S. paratyphi C, and homologous S. paratyphi A.
- Immunized mice were challenged with a toxic concentration of S. paratyphi A.
- Neutralizing antibody levels were assessed, and cross-reactivity was evaluated using agar-gel precipitation tests.
Main Results:
- Immunization with S. typhimurium and S. paratyphi C proteins conferred resistance to S. paratyphi A toxicity.
- A higher dose of homologous S. paratyphi A proteins was required to neutralize S. paratyphi A toxicity compared to heterologous proteins.
- Agar-gel tests revealed cross-reactivity between S. paratyphi A proteins and those from S. typhimurium and S. paratyphi C in sera with induced neutralizing antibodies.
Conclusions:
- Proteins from S. typhimurium and S. paratyphi C induce cross-protective immunity against S. paratyphi A toxicity.
- S. paratyphi A appears to be a weak immunogen or produces limited immunogenic proteins in vitro.
- Cross-reactivity in immune sera suggests shared antigenic determinants among these Salmonella serotypes.