Protection Against Meningococcal Challenge Afforded Mice After Immunization with Typhoid-Paratyphoid Vaccine USP
A R Banknieder1, L F Devine, C A Faust
1Naval Medical Research Unit No. 4, Great Lakes, Illinois 60088.
Abstract:
Mice immunized with typhoid-paratyphoid vaccine USP were found to be protected when challenged with serological groups A, B, and C of Neisseria meningitidis. Mice immunized with this vaccine both 14 and 7 days prior to challenge were protected against mean lethal doses (LD(50)) of 5,220 and 1,151 of groups A and B, respectively, and in two separate experiments they were protected against 3,568 and 268 LD(50) of group C. Mice immunized four or more times on successive days prior to challenge were also protected. They demonstrated tolerance and survived a much larger LD(50) challenge than mice immunized by any other immunization schedule. Mice immunized once or twice anytime within 7 days prior to challenge were not protected and thus failed to exhibit nonspecific resistance. Serum antibody probably was responsible for the protection afforded mice immunized 14 and 7 days prior to challenge. However, this was not demonstrated conclusively.
Insights
Mice immunized with typhoid-paratyphoid vaccine showed protection against Neisseria meningitidis serogroups A, B, and C. Multiple immunizations conferred significant protection and tolerance against lethal doses.
Area of Science:
- Immunology
- Vaccinology
- Microbiology
Background:
- Neisseria meningitidis poses a significant global health threat.
- Effective vaccines are crucial for controlling meningococcal disease outbreaks.
- Understanding vaccine efficacy and immune responses is vital.
Purpose of the Study:
- To evaluate the protective efficacy of typhoid-paratyphoid vaccine against Neisseria meningitidis challenge in mice.
- To investigate the impact of different immunization schedules on protection and tolerance.
Main Methods:
- Mice were immunized with typhoid-paratyphoid vaccine USP.
- Immunized mice were challenged with lethal doses (LD50) of Neisseria meningitidis serogroups A, B, and C.
- Protection and survival rates were assessed based on varying immunization timings and frequencies.
Main Results:
- Vaccination provided protection against serogroups A, B, and C of Neisseria meningitidis.
- Mice immunized 14 and 7 days prior to challenge survived high LD50 doses.
- Multiple immunizations (four or more) resulted in enhanced protection and tolerance to higher LD50 challenges.
- Single or double immunizations within 7 days prior to challenge did not confer protection.
Conclusions:
- Typhoid-paratyphoid vaccine demonstrates cross-protective potential against Neisseria meningitidis.
- Optimal immunization schedules are critical for achieving robust protection and tolerance.
- Further studies are needed to conclusively establish the role of serum antibodies in this observed protection.
