Changes

*RTX toxins:

*RTX toxins:

**'Repeat in ToXin' - named because there are several peptide repeats within the molecules

**'Repeat in ToXin' - named because there are several peptide repeats within the molecules

**Produced by various Gram-negative bacteria, including [[Escherichia coli|''E. coli'']], [[Bordetella|''Bordetella sp.'']] and [[''Pasteurella haemolytica#Pasterurella''|''Pasteurella haemolytica'']]

**Produced by various Gram-negative bacteria

**Possess four contiguous genes, C, A, B and D

**Possess four contiguous genes, A, B, C and D

**A is the structural gene; B and D are required for secretion; C is required for post-translational activation of the gene product of A to produce a functional product

**A is the structural gene; B and D are required for secretion; C allows post-translational activation of the gene product of A into a functional product

**ApxI is a strong haemolysin with cytolytic activity

**ApxI is a strong haemolysin with cytolytic activity

**ApxII is a weak haemolysin  

**ApxII is a weak haemolysin  

**ApxIII is a cytotoxin

**ApxIII is a cytotoxin

**Different ''Actinobacillus pleuropneumonia'' serotypes secrete a particular combination of toxins; American serotypes secrete ApxI and II; European serotypes secrete ApxII and III

**Different ''Actinobacillus pleuropneumonia'' serotypes secrete a particular combination of toxins; American serotypes secrete ApxI and II; European serotypes secrete ApxII and III