a Prevent Complement Activation "t Masking surface components that activate by the alternative pathway Capsules Murein of s, aureus good activator, but is covered by capsule Capsules rich in sialic acid of Group B streptococci and strains of e,co∥ BIOL 533 7 Lecture 8
BIOL 533 7 Lecture 8 Prevent Complement Activation • Masking surface components that activate by the alternative pathway – Capsules • Murein of S. aureus good activator, but is covered by capsule • Capsules rich in sialic acid of Group B streptococci and strains of E. coli
a Prevent Complement Activation "t IgA antibodies Meningococci get coated with IgA antibody Does not activate complement Prevents other ab that can activate from reaching surface of cell BIOL 533 Lecture 8
BIOL 533 8 Lecture 8 Prevent Complement Activation – IgA antibodies • Meningococci get coated with IgA antibody – Does not activate complement – Prevents other Ab that can activate from reaching surface of cell
a Prevent Complement Activation "t Cost of having capsule- antigenic Elicits activation by primary pathway Defend better against immediate defenses than later ones BIOL 533 Lecture 8
BIOL 533 9 Lecture 8 Prevent Complement Activation • Cost of having capsule— antigenic – Elicits activation by primary pathway • Defend better against immediate defenses than later ones
a Prevent Complement Activation "t Cover up target of membrane attack complex(outer membrane) Gram, such as salmone∥aorE,CO∥ Smooth strains with long 0 antigen polysaccharide chain do not allow access of mac while rough strains(with little or no 0 antigen)do Correlates with pathogenicity BIOL 533 Lecture 8
BIOL 533 10 Lecture 8 Prevent Complement Activation • Cover up target of membrane attack complex (outer membrane) – Gram—, such as Salmonella or E. coli • Smooth strains with long ‘0’ antigen polysaccharide chain do not allow access of mac while rough strains (with little or no ‘0’ antigen) do – Correlates with pathogenicity
Subversion of phagocytosis Overall str ategies Inhibition of phagocyte recruitment Microbial killing of phagocytes Escape of ingestion BIOL 533 Lecture 8
BIOL 533 11 Lecture 8 Subversion of Phagocytosis • Overall strategies – Inhibition of phagocyte recruitment – Microbial killing of phagocytes – Escape of ingestion