Actinobacillus suis

Also known as: A.suis

Scientific Classification
Kingdom	Bacteria
Phylum	Proteobacteria
Class	Zymobacteria
Sub-class	Alphaproteobacteria
Order	Pasteurellales
Family	Pasteurellaceae
Genus	Actinobacillus
Species	Actinobacillus suis

Introduction

A.suis is a beta-haemolytic Gram-negative bacterium. Strains of A.Suis vary due to differences in their lipopolysaccharides (LPS), which is known as the 'O' antigen and is referred to as O1,O2 and O3 and capsules (CPS), called 'K' antigen with variants described as K1, K2 and K3. More than 95% of A. suis clinical isolates are cross-reactive with O1/K1 or O2/K3 antiserum and more severe infection were noted with O2/K2 srain(Slavic et al., 2000). The bacteria causes Actinobacillosis in pigs, horses, cattle and can infect [[Actinobacillus suis#signalment| various other species.

A.suis have genes that encode toxins similar to apxI and apxII of A. pleuropneumoniae, but they are less virulent. Once an animal is infected with A.suis it can provide partial cross protection against A. pleuropneumoniae.

Most of the O1 strains analyzed to date possess pustulan (1-6,beta-D-glucan)which is a major component of fungal and lichen cell walls. Therefore, many animals have antibodies to this polysaccharide in the absence of exposure to A. suis, which may provide naive pigs with some level of protection against the O1 strains (MacInnes and Desrosiers, 1999; Slavic et al., 2000).

Signalment

A.Suis can be found worldwide in both healthy and diseased animals which are genetically and biochemically similar. It is believed to be spread via aerososl infection and invasion of the upper respiratory tract. Wild hosts include anatidae (ducks, geese and swans) and Coypu but A.suis can also affect domestic species including pigs, horses, cattle, sheep, goats, alpacas, zebu, dogs, and cats.