Related Experiment Video
Updated: Aug 13, 2026
Humanized Mouse Model to Study Bacterial Infections Targeting the Microvasculature
Published on: April 1, 2014
Experimental meningococcal infection in neonatal mice: differences in virulence between strains isolated from human
Abstract:
The lack of availability of a suitable animal model has limited understanding of the pathophysiology of meningococcal disease. We have utilized a neonatal mouse model in which atraumatic intranasal inoculation of meningococci results in nasopharyngeal colonization and ultimately bacteremia. Using this model, we compared the virulence of seven encapsulated meningococcal carrier strains with eight meningococcal strains which were isolated from cerebrospinal fluid or blood of patients (disease strains). Intraperitoneal (IP) iron dextran was given to some animals to enhance meningococcal virulence. After IP iron, carrier strains were still poorly invasive with rates of bacteremia ranging from 0 to 15% (mean = 3%), whereas disease-associated strains were significantly more invasive and caused bacteremia in 31-64% of animals (mean = 39%). Without iron injections, nasopharyngeal colonization rates were similar (36 versus 30%, P greater than 0.1) for case and carrier strains. IP iron dextran significantly enhanced rates of colonization and bacteremia caused by the disease strains only. We have, therefore, shown that the relative virulence of meningococcal strains for humans is maintained in this experimental model.
Insights
A new mouse model reveals meningococcal disease strains are more virulent than carrier strains, especially after iron administration. This model helps understand meningococcal disease pathophysiology.
Area of Science:
- Microbiology
- Pathophysiology
- Infectious Diseases
Background:
- Understanding meningococcal disease pathophysiology is limited by the lack of suitable animal models.
- Neonate mice can be intranasally inoculated with meningococci to establish nasopharyngeal colonization and bacteremia.
Purpose of the Study:
- To compare the virulence of meningococcal carrier strains versus disease strains in a neonatal mouse model.
- To investigate the effect of iron dextran administration on meningococcal virulence in this model.
Main Methods:
- Neonatal mice were intranasally inoculated with either carrier or disease strains of meningococci.
- Some mice received intraperitoneal (IP) iron dextran to enhance virulence.
- Rates of nasopharyngeal colonization and bacteremia were compared between strain types and with or without iron administration.
Main Results:
- Disease strains were significantly more invasive, causing bacteremia in 31-64% of mice compared to 0-15% for carrier strains, particularly after IP iron dextran.
- Without iron, colonization rates were similar for both strain types (36% vs. 30%).
- IP iron dextran significantly enhanced colonization and bacteremia rates only for disease strains.
Conclusions:
- The neonatal mouse model effectively replicates the relative virulence of meningococcal strains observed in humans.
- Iron availability plays a crucial role in the invasiveness of disease-associated meningococcal strains.
