The role of RTX toxins in host specificity of animal pathogenic Pasteurellaceae

Frey, J (2011). The role of RTX toxins in host specificity of animal pathogenic Pasteurellaceae. Veterinary microbiology, 153(1-2), pp. 51-8. Amsterdam: Elsevier 10.1016/j.vetmic.2011.05.018

Full text not available from this repository. (Request a copy)

RTX toxins are bacterial pore-forming toxins that are particularly abundant among pathogenic species of Pasteurellaceae, in which they play a major role in virulence. RTX toxins of several primary pathogens of the family of Pasteurellaceae are directly involved in causing necrotic lesions in the target organs. Many RTX toxins are known as haemolysins because they lyse erythrocytes in vitro, an effect that is non-specific, but which serves as a useful marker in bacteriological identification and as an easily measurable signal in vitro in experimental studies. More recent studies have shown that the specific targets of most RTX toxins are leukocytes, with RTX toxins binding to the corresponding beta-subunit (CD18) of beta2 integrins and then exerting cytotoxic activity. After uptake by the target cell, at sub-lytic concentrations, some RTX toxins are transported to mitochondria and induce apoptosis. For several RTX toxins the binding to CD18 has been shown to be host specific and this seems to be the basis for the host range specificity of these RTX toxins. Observations on two very closely related species of the Pasteurellaceae family, Actinobacillus suis, a porcine pathogen particularly affecting suckling pigs, and Actinobacillus equuli subsp. haemolytica, which causes pyosepticaemia in new-born foals (sleepy foal disease), have revealed that they express different RTX toxins, named ApxI/II and Aqx, respectively. These RTX toxins are specifically cytotoxic for porcine and equine leukocytes, respectively. Furthermore, the ApxI and Aqx toxins of these species, when expressed in an isogenetic background in Escherichia coli, are specifically cytotoxic for leukocytes of their respective hosts. These data indicate the determinative role of RTX toxins in host specificity of pathogenic species of Pasteurellaceae.

Item Type:

Journal Article (Original Article)


05 Veterinary Medicine > Department of Infectious Diseases and Pathobiology (DIP) > Institute of Veterinary Bacteriology

UniBE Contributor:

Frey, Joachim








Factscience Import

Date Deposited:

04 Oct 2013 14:31

Last Modified:

21 Jan 2014 15:05

Publisher DOI:


Web of Science ID:


URI: (FactScience: 218411)

Actions (login required)

Edit item Edit item
Provide Feedback