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Actinobacillus species (view source)
Revision as of 15:18, 20 December 2007
, 15:18, 20 December 2007no edit summary
===''Actinobacillus pleuropneumoniae''===
===''Actinobacillus pleuropneumoniae''===
*Contagious porcine pleuropneumonia
*Contagious porcine pleuropneumonia especially of pigs under 6 months
*Endemic in UK
*Endemic in UK
*Most strains are NAD-dependent (grow on Heated Blood agar)
*Most strains are NAD-dependent (grow on Heated Blood agar)
*12 serotypes causing the same disease
*12 serotypes causing the same disease
*Different serotypes in different regions, with serotypes 3,6 and 8 the most common in the UK
*Different serotypes in different regions, with serotypes 3,6 and 8 the most common in the UK
*Pathogenesis and pathogenicity:
**Virulent strains possess capsules which are antiphagocytic and immunogenic
**Fimbriae allow the bacteria to attach to cells of the respiratory tract
**Produce three cytotoxins which belong to the repeats-in-structural-toxin (RTX) cytolysin family
**RTX toxins:
***Several peptide repeats within the molecules
***Produced by various Gram-negative bacteria
***Possess four contiguous genes, A, B, C and D
***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
***ApxII is a weak haemolysin
***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
*Acute disease in susceptible herds with high morbidity and mortality
*Acute disease in susceptible herds with high morbidity and mortality
*Causes [[Bacterial infections#Actinobacillus pleuropneumoniae|pneumonia]] in pigs
*Causes [[Bacterial infections#Actinobacillus pleuropneumoniae|pneumonia]] in pigs
*The bacteria on the palatine tonsil are undetected by serologucal tests and swabbing, and can therefore cause an outbreak in naive pigs
*The bacteria on the palatine tonsil are undetected by serologucal tests and swabbing, and can therefore cause an outbreak in naive pigs
*Killed and bacterin vaccines are available
*Killed and bacterin vaccines are available