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Recall of immunity in mice vaccinated with Salmonella enteritidis or Salmonella typhimurium
Abstract:
Mice were immunized with living Salmonella enteritidis or S. typhimurium and then were reinfected 8, 30, 60, and 150 days later with streptomycin-resistant strains of S. enteritidis, S. typhimurium, or a mixture of the two organisms. The level of resistance at the time of challenge and the rate at which resistance was recalled in late convalescence was determined by daily liver and spleen counts of the challenge population. An immediately effective specific antibacterial immunity was maintained only while the vaccinating strain could still be detected in the liver and spleen. Reinfection of vaccine-free mice with the homologous organism caused a rapid recall of antibacterial immunity (within 3 days), but the response to the heterologous organism was much slower (5 to 8 days). Simultaneous injection of both pathogens into the vaccinated mice resulted in liver and spleen growth curves which resembled those obtained when the two organisms were administered separately. The implications of these growth studies in the development of specific cellular immunity to Salmonella infections are discussed.
Insights
Vaccinating mice with Salmonella enteritidis or S. typhimurium induced specific immunity. This antibacterial immunity was maintained as long as the vaccine strain persisted, with rapid recall upon homologous reinfection.
Area of Science:
- Immunology
- Microbiology
- Infectious Diseases
Background:
- Salmonella infections pose a significant public health challenge.
- Understanding the dynamics of Salmonella immunity is crucial for vaccine development.
Purpose of the Study:
- To investigate the duration and recall kinetics of Salmonella-specific antibacterial immunity in mice.
- To determine the impact of homologous and heterologous reinfection on immune recall.
Main Methods:
- Mice were immunized with live Salmonella enteritidis or S. typhimurium.
- Reinfection was performed at various time points with streptomycin-resistant strains.
- Liver and spleen bacterial counts were used to assess resistance and immune recall.
Main Results:
- Specific antibacterial immunity persisted only while the vaccinating Salmonella strain was detectable in host tissues.
- Homologous reinfection rapidly recalled immunity within 3 days.
- Heterologous reinfection elicited a slower immune response, taking 5-8 days.
Conclusions:
- The duration of Salmonella-specific immunity is linked to the persistence of the immunizing agent.
- Rapid immune recall is observed with homologous challenge, while heterologous challenge requires a more extended response.
- These findings have implications for developing effective cellular immunity strategies against Salmonella infections.