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Limited protective effect of rough mutant antisera in murine Escherichia coli bacteremia
Abstract:
Previous studies in mice have demonstrated differing immunoprophylactic activity of antisera against rough mutants of Enterobacteriaceae in the prevention of lethal gram-negative bacteremia. In this study, in which CF1 mice were made bacteremic with a serum-resistant Escherichia coli 06:K2:H1, the composite survival was significantly (p less than 0.001) enhanced by i. v. pre-treatment one to two hours before injection with either normal rabbit sera or antisera to the J5 mutant of E. coli 0111. The protective efficacy of these preimmune and hyperimmune sera did not differ significantly. Since considerable variability in the mortality of control mice occurred in the 25 separate experiments, the results of individual experiments were grouped retrospectively according to survival in the individual control groups and compared for evidence of possible differences in the efficacy of these two sera. With the exception of a statistically significant difference in the efficacy in one group receiving an LD75-95 inoculum, no such differences were noted. Thus, the variable effects of a rough mutant antiserum were not explained by differences in the relative virulence in the inoculum. This study confirms earlier observations by others that the protective efficacy of the anti-J5 antisera in infected mice does not differ appreciably from that of normal rabbit sera, provided the same donor rabbits are the source of both preimmune and hyperimmune sera.
Insights
Normal rabbit sera and J5 mutant antisera showed similar protective effects against lethal gram-negative bacteremia in mice. This suggests that anti-J5 antisera efficacy is comparable to normal sera in preventing E. coli infections.
Area of Science:
- Immunology
- Microbiology
- Infectious Diseases
Background:
- Previous research indicated varied immunoprophylactic activity of antisera against Enterobacteriaceae rough mutants.
- Gram-negative bacteremia remains a significant clinical challenge, necessitating effective preventative strategies.
Purpose of the Study:
- To evaluate the immunoprophylactic efficacy of antisera against a serum-resistant Escherichia coli strain.
- To compare the protective effects of normal rabbit sera and antisera against the J5 mutant of E. coli.
Main Methods:
- CF1 mice were infected with a serum-resistant E. coli strain (06:K2:H1).
- Mice received intravenous pre-treatment with either normal rabbit sera or anti-J5 mutant antisera one to two hours before infection.
- Survival rates were analyzed, and experiments were retrospectively grouped to assess serum efficacy under varying control group mortality.
Main Results:
- Both normal rabbit sera and anti-J5 antisera significantly enhanced composite survival (p < 0.001) in bacteremic mice.
- No significant difference was observed in the protective efficacy between preimmune (normal) and hyperimmune (anti-J5) sera.
- Variability in control mouse mortality did not explain differences in rough mutant antiserum efficacy, except in one instance with a high inoculum.
Conclusions:
- The protective efficacy of anti-J5 antisera against E. coli bacteremia in mice is comparable to that of normal rabbit sera.
- The study confirms that anti-J5 antisera do not offer significantly greater protection than normal sera when derived from the same rabbit source.
- Variations in inoculum virulence did not account for the observed effects of rough mutant antiserum.