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The virulence in mice of Neisseria meningitidis variants differing in free endotoxin activities and cell envelope
Abstract:
The virulence of two serogroup B meningococcal strains (270E+ and 840E+) having a high endotoxin release during in vitro growth, was compared with the virulence of corresponding variants (270E- and 840E-) liberating less endotoxin. The E-variants were isolated during subcultivations from the E+ strains. 270E+ and 840E+ were both serotype 15:P1.16, while 270E- was serotype 15:P1.2 and 840E- was non-typable. The SDS-PAGE patterns of the E+ and E- variants were also dissimilar. The E+ and E- variants differed in several other properties. Groups of mice were inoculated intravenously (i.v.) or intraperitoneally (i.p.) with E+ and E- meningococci. The endotoxin activities of inoculates and mouse blood were assayed by a Limulus lysate test. The mice received a similar infective dose of E+ and E- variants. A higher level of CFU and endotoxin was found in heart blood of E+ than of E-infected mice during the first hours after infection. Both 30h and 72h after inoculation, E+ variants were significantly more lethal to mice than E- variants (p less than 0.01).
Insights
High endotoxin release in meningococcal strains correlates with increased virulence. Strains with greater endotoxin liberation proved significantly more lethal in mouse models, highlighting endotoxin
Area of Science:
- Microbiology and Immunology
- Pathogen Virulence Studies
Background:
- Neisseria meningitidis serogroup B strains exhibit varying endotoxin release levels.
- Endotoxin production is a key factor in bacterial pathogenesis.
Purpose of the Study:
- To compare the virulence of meningococcal strains with high endotoxin release (E+) versus low endotoxin release (E-).
- To investigate the role of endotoxin levels in meningococcal disease severity.
Main Methods:
- Comparison of in vitro endotoxin release and in vivo virulence in mouse models.
- Intravenous and intraperitoneal inoculation of mice with characterized meningococcal strains.
- Assay of endotoxin activity and bacterial load (CFU) in mouse blood using Limulus lysate test.
Main Results:
- Meningococcal strains with high endotoxin release (E+) demonstrated significantly higher lethality in mice compared to low endotoxin variants (E-).
- Elevated levels of endotoxin and colony-forming units (CFU) were detected in the blood of mice infected with E+ strains during early infection.
- Distinct serotypes and SDS-PAGE patterns were observed between E+ and E- variants.
Conclusions:
- High endotoxin release is directly associated with increased virulence and lethality of serogroup B meningococcal strains.
- Endotoxin levels are a critical determinant of Neisseria meningitidis pathogenicity.
- Further research into endotoxin's role could inform therapeutic strategies against meningococcal infections.