Question

what are the main difference of the virulent and non-virulent strain of Streptococcus pneumonia?

Answer 1

Streptococcus pneumoniae has two strains virulent and non- virulent called S strain and R strain respectively. The S strain ( virulent strain) produces a mucus polysaccharide coat while the R strain ( non virulent) does not. This polysaccharide coat is responsible for virulence. It inhibits host immune response and so allows bacteria in causing a disease.