THE TRANSFORMATION OF PNEUMOCOCCAL TYPES : I. THE CONVERSION OF R FORMS OF PNEUMOCOCCUS INTO S FORMS OF THE...

Area of Science:

• Microbiology
• Bacteriology
• Genetics

Background:

• Pneumococcus R forms can be converted into homologous S forms.
• Previous methods for conversion included animal passage and growth in anti-R sera.

Purpose of the Study:

• To investigate new methods for converting Pneumococcus R forms into S forms.
• To explore the stability of R variants and the potential for further degradation.
• To assess the efficacy of different vaccine preparations and heat treatments in the conversion process.

Main Methods:

• Subcutaneous injection of large amounts of living R organisms into white mice.
• Subcutaneous injection of small amounts of living R organisms combined with heat-killed homologous S bacteria into white mice.
• Utilizing heat-killed Type I, II, and III S vaccines subjected to different temperatures (60°C and 100°C) for 15 minutes.

Main Results:

• Conversion of all selected R forms was achieved using the described methods.
• Attempts to further degrade R organisms by prolonged growth in homologous immune serum were unsuccessful.
• Type II and III S vaccines were equally effective after heating at 60°C or 100°C.
• Type I S vaccine lost its conversion property after heating at 100°C, but not at 60°C.
• R vaccines or vaccines from other organisms did not induce conversion when co-injected with live R cultures.

Conclusions:

• Specific experimental conditions, particularly the use of heat-killed homologous S bacteria, can induce the transformation of Pneumococcus R forms into S forms.
• The heat stability of the transforming principle varies between different Pneumococcus types (e.g., Type I vs. Types II and III).
• The findings suggest the possibility of similar transformation processes occurring naturally in human populations.