*Lung scarring and pleural adhesions in many recovered animals
*Lung scarring and pleural adhesions in many recovered animals
*Solid immunity develops in recovered animals to all serotypes
*Solid immunity develops in recovered animals to all serotypes
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*The disease is spread between herds by carrier pigs
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*The bacteria on the palatine tonsil are undetected by serologucal tests and swabbing, and can therefore cause an outbreak in naive pigs
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*Killed and bacterin vaccines are available
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*Produce one or two RTX group cytolytic toxins
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*RTX toxins:
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**'Repeat in ToXin' - named because there are several peptide repeats within the molecules
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**Produced by various Gram-negative bacteria, including
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**Possess four contiguous genes, C, A, B and D
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**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
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**ApxI is a strong haemolysin with cytolytic activity
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**ApxII is a weak haemolysin
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**ApxIII is a cytotoxin
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**Different ''Actinobacillus pleuropneumonia'' serotypes secrete a particular combination of toxins; American serotypes secrete ApxI and II; European serotypes secrete ApxII and III