Virulence factors Antigens Somatic O"LPS Major cell wall Ag; heat stable Specifico"antigens associated with each genus; however, cross reactions are common Salmonella and citrobacter Escherichia and Shigella BIOL 533 7 Lecture 12
BIOL 533 7 Lecture 12 Virulence Factors • Antigens – Somatic “O” LPS • Major cell wall Ag; heat stable • Specific “O” antigens associated with each genus; however, cross reactions are common – Salmonella and Citrobacter – Escherichia and Shigella
Virulence factors Capsular K Either protein or polysaccharide e Heat-labile May interfere with detection of"O o Removed by boling organisms Capsular antigen of salmonela typhi referred to as Vi antigen BIOL 533 Lecture 12
BIOL 533 8 Lecture 12 Virulence Factors • Capsular K – Either protein or polysaccharide • Heat-labile • May interfere with detection of “O” • Removed by boiling organisms – Capsular antigen of Salmonella typhi referred to as Vi antigen
Virulence factors Capsular K, continued Shared by different genera both inside and outside of family ● Cross reactions E. coliKl with N, meningitidis and Haemophilus meningitidis K pneumoniae with S pneunomiae Organisms with specific antigens have been associated with increased virulence (e.g. E. collKl with neonatal meningitis) BIOL 533 Lecture
BIOL 533 9 Lecture 12 Virulence Factors • Capsular K, continued – Shared by different genera both inside and outside of family • Cross reactions – E. coli K1 with N. meningitidis and Haemophilus meningitidis – K. pneumoniae with S. pneunomiae – Organisms with specific antigens have been associated with increased virulence (e.g., E. coli K1 with neonatal meningitis)
Virulence factors Flagella h Heat-labile proteins Can be absent or undergo antigenic variation (present in two phases) Specific h antigens assocated with disease BIOL 533 Lecture 12
BIOL 533 10 Lecture 12 Virulence Factors • Flagella H – Heat-labile proteins • Can be absent or undergo antigenic variation (present in two phases) • Specific H antigens assocated with disease
Virulence factors General role in pathogenesis ofˇO"“K and H"antigens Specific antigens associated with meningitis, gastroenteritis, and urinary tract infections Role that Ag's play in these diseases is not clear Some capsular Ag are poor immunogens Protect against antibody-mediated phagocytosis Flagellar Ag probably play a role in adherence BIOL 533 Lecture
BIOL 533 11 Lecture 12 Virulence Factors • General role in pathogenesis of “O,” “K,” and “H” antigens – Specific antigens associated with meningitis, gastroenteritis, and urinary tract infections • Role that Ag’s play in these diseases is not clear – Some capsular Ag are poor immunogens • Protect against antibody-mediated phagocytosis – Flagellar Ag probably play a role in adherence