Inhibition of phage infection by pneumococcus capsule.

Abstract Fifty-two strains of pneumococci were tested for sensitivity to lysis by pneumococcus phages ω2, ω3, and ω8. Nine noncapsulated strains derived from seven different wildtype strains were all lysed by the three phages. Two strains carrying the C s capsule were as sensitive as their parent noncapsulated strains. Forty-one other capsulated strains were insensitive to lysis by any of the phages. Although capsulation apparently severely limits adsorption of phage, capsulated cells can release phage; infection by ω3 of a type 3 pneumococcus temporarily denuded of its capsule by enzymatic action resulted in a burst of progeny phage at a time when the host cell had regained full capsulation.