THE REVERSION OF R TO S PNEUMOCOCCI.

Area of Science:

• Microbiology
• Bacteriology
• Genetics

Background:

• Streptococcus pneumoniae exists in virulent (S) and non-virulent (R) forms.
• Understanding the behavior and transformation of these pneumococcal strains is crucial for infectious disease research.

Purpose of the Study:

• To investigate the behavior and transformation potential of R pneumococcus strains under various experimental conditions.
• To explore the conditions under which R forms can revert to S forms or transform into different types.

Main Methods:

• Cultivation of R pneumococcus strains under diverse experimental settings.
• Observation of colony morphology and bacterial characteristics.
• In vivo studies involving prolonged residence of bacterial forms.
• Application of Griffith's methods for bacterial transformation.

Main Results:

• R strains frequently produced 'daughter' colonies, morphologically resembling S colonies but retaining R characteristics.
• Both R and daughter forms, after prolonged in vivo residence, converted to virulent forms.
• Seemingly irreversible R strains transformed into S forms using Griffith's methods.
• Virulent S pneumococci can dissociate into R forms in vivo.
• R forms can be found in pneumonia patient sputum and can remain dormant in vivo.
• R forms can spontaneously revert to S forms or transform into other S types under favorable conditions.

Conclusions:

• Pneumococcus R forms exhibit significant plasticity, capable of reverting to or transforming into virulent S forms.
• Environmental and experimental conditions, including in vivo residence and specific transformation methods, play a key role in pneumococcal strain behavior.
• The study highlights the dynamic nature of pneumococcal virulence and the potential for interconversion between R and S forms.