Explain griffin experiment ?

Griffith’s Experiment

Griffith experimented with Streptococcus pneumoniae bacteria. This bacteria causes Pneumonia.Two strains of this bacteria were used R-strain & S-strain.

• S strain
  • Smooth mucous polysaccharide coat
  • Resistant to immune system
  • Virulent
• R strain
  • Lacks the coat
  • Destroyed by immune system of the host
  • Non-virulent

The experiment was performed in multiple steps.

1. S-strain (virulent) was injected into mouse. It was found that the mouse died of pneumonia
2. R-strain (non-virulent) was injected into mouse. It was found that the mouse remained alive .
3. Heat killed S-strain (S-strain bacteria were killed by heating) was injected into mouse. It was found that the mouse remained alive .
4. Heat killed S-strain & live R-strain were injected into mouse. It was found that the mouse died of pneumonia