title: AvxA, a composite serine-protease-RTX toxin of Avibacterium paragallinarum.
abstract: Avibacterium paragallinarum, the etiological agent of infectious coryza in chicken, was found to encode a bivalent serine-protease - RTX-porin toxin named AvxA. This toxin is encoded on a classical RTX operon structure with the activator gene avxC, the structural serin-protease-RTX toxin gene avxA, and the genes for a proper type I secretion system avxBD. AvxA is activated by the product of the avxC gene, secreted by the avxBD specified type I secretion system and proteolytically processed leaving a 95 kDa RTX moiety that is found in culture supernatants of A. paragallinarum serovars A, B and C. The RTX moiety of AvxA (AvxA-RTX) is cytotoxic against the avian macrophage like cell line HD11 but not against bovine macrophage cell line BoMac. Purified IgG from hyper-immune rabbit anti-AvxA-RTX serum made by immunization with recombinant AvxA-RTX from a serotype A strain fully neutralizes the cytotoxic activity of recombinant active AvxA-RTX and of A. paragallinarum serotypes A, B and C. This indicates that AvxA is a common major virulence attribute of all A. paragallinarum serotypes.
authors: Institute of Veterinary Bacteriology, University of Bern, Bern, Switzerland.
authors: Eliane
authors: E
authors: Küng
authors: Joachim
authors: J
authors: Frey
mesh_terms: D000818:Animals; D000907:Antibodies, Bacterial / Q000378:metabolism; D058947:Bacterial Secretion Systems; D001427:Bacterial Toxins / Q000378:metabolism*; D002417:Cattle; D002460:Cell Line; D002645:Chickens; D000939:Epitopes; D006192:Haemophilus Infections / Q000201:enzymology* / Q000382:microbiology; D044134:Haemophilus paragallinarum / Q000201:enzymology* / Q000235:genetics; D009876:Operon / Q000235:genetics; D011994:Recombinant Proteins / Q000378:metabolism; D012697:Serine Endopeptidases / Q000378:metabolism; D057057:Serine Proteases / Q000378:metabolism*
chemical_list: D000907:Antibodies, Bacterial; D058947:Bacterial Secretion Systems; D001427:Bacterial Toxins; D000939:Epitopes; D011994:Recombinant Proteins; D057057:Serine Proteases; D012697:Serine Endopeptidases