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[The isolation and characteristics of variant plague microbes not producing the capsular antigen]
Abstract:
Fifteen stable variants of Yersinia pestis strains exhibiting different degrees of virulence for white mice and guinea pigs were obtained. Multiple passages of the organisms at 37 degrees C in a fluid nutrient medium containing antiplague agglutinating serum were found to be the most efficient method for obtaining noncapsular forms of the plague agent. Acquisition of the Fra(-) phenotype both by wild and laboratory strains was not associated with a loss of the high-molecular plasmid by cells but was probably a result of mutational alterations in the plasmid genes.
Insights
Researchers developed stable Yersinia pestis variants with varying virulence. The most effective method for creating non-encapsulated plague variants involved repeated culturing in nutrient broth with anti-plague serum.
Area of Science:
- Microbiology
- Bacteriology
- Pathogen Research
Background:
- Yersinia pestis is the causative agent of plague, a severe infectious disease.
- Virulence factors, such as capsular antigens, play a critical role in Y. pestis pathogenesis.
- Understanding the genetic basis of virulence is crucial for developing effective countermeasures.
Purpose of the Study:
- To generate stable Yersinia pestis variants with differential virulence.
- To identify efficient methods for producing non-encapsulated (Fra-) Y. pestis strains.
- To investigate the genetic mechanisms underlying the acquisition of the Fra- phenotype.
Main Methods:
- Obtaining fifteen stable Yersinia pestis variants with varying virulence in mice and guinea pigs.
- Employing multiple passages at 37°C in nutrient broth containing anti-plague agglutinating serum to select for non-encapsulated forms.
- Analyzing the presence of the high-molecular plasmid in Fra- variants.
Main Results:
- Fifteen stable Yersinia pestis variants with distinct virulence levels were successfully generated.
- Repeated culturing in serum-supplemented broth proved to be an efficient method for obtaining non-encapsulated plague variants.
- The Fra- phenotype acquisition in both wild-type and laboratory strains was not linked to plasmid loss but likely resulted from mutations within plasmid genes.
Conclusions:
- Stable Yersinia pestis variants can be generated to study virulence.
- Culturing in anti-plague serum is an effective method for producing non-encapsulated Y. pestis.
- Mutations in plasmid genes, rather than plasmid loss, are likely responsible for the Fra- phenotype in Y. pestis.