AB5 Toxins as Components of Vaccines: Characterization of Salmonella ArtAB and E.coli LT
Abstract
Bacterial AB5 toxins are complex multi-component structures characterized by their structural composition, consisting of an A and B subunit. The A subunit is the catalytic portion and thus induces a toxic effect. The B subunit forms a stable pentameric ring and acts as the receptor-binding domain, attaching to the cell surface. Non-toxic forms of these proteins are being investigated for their potential application as adjuvants in vaccines for the enhancement of immune protection. Here we have specifically looked at two AB5 toxins: ArtAB from Salmonella and heat-labile toxin (LT) from E. coli. Salmonella enterica causes one of the most common foodborne illnesses in the United States, affecting both humans and animals. The Salmonella enterica Typhimurium DT104 phage type possesses the ADP-ribosylating toxin known as ArtAB. We have previously cloned artAB and its pentameric receptor-binding subunit (artB). Here we used bioinformatics to determine the prevalence of the artB gene in Salmonella from different hosts, and the homology of this gene to other known toxins. In addition, we purified ArtAB and ArtB for use in downstream activity assays such as ADP-ribosylation. E. coli is a type of bacteria that lives in the intestines. Enterotoxigenic Escherichia coli (ETEC) is a strain that produces the AB5 toxin known as heat-labile toxin (LT), which is very closely related to cholera toxin (CT) and possesses adjuvant properties. Here we cloned the eltAB genes that encode LT and purified LT. Further testing and comparisons between the holotoxins (both subunits) and the B-subunits, such as how they similarly modulate the immune system, is needed to give evidence into potential adjuvant activity for use as preventatives against Salmonella and ETEC. These studies will also increase our understanding of how these toxins contribute to infection and pathogenesis.
AB5 Toxins as Components of Vaccines: Characterization of Salmonella ArtAB and E.coli LT
Bacterial AB5 toxins are complex multi-component structures characterized by their structural composition, consisting of an A and B subunit. The A subunit is the catalytic portion and thus induces a toxic effect. The B subunit forms a stable pentameric ring and acts as the receptor-binding domain, attaching to the cell surface. Non-toxic forms of these proteins are being investigated for their potential application as adjuvants in vaccines for the enhancement of immune protection. Here we have specifically looked at two AB5 toxins: ArtAB from Salmonella and heat-labile toxin (LT) from E. coli. Salmonella enterica causes one of the most common foodborne illnesses in the United States, affecting both humans and animals. The Salmonella enterica Typhimurium DT104 phage type possesses the ADP-ribosylating toxin known as ArtAB. We have previously cloned artAB and its pentameric receptor-binding subunit (artB). Here we used bioinformatics to determine the prevalence of the artB gene in Salmonella from different hosts, and the homology of this gene to other known toxins. In addition, we purified ArtAB and ArtB for use in downstream activity assays such as ADP-ribosylation. E. coli is a type of bacteria that lives in the intestines. Enterotoxigenic Escherichia coli (ETEC) is a strain that produces the AB5 toxin known as heat-labile toxin (LT), which is very closely related to cholera toxin (CT) and possesses adjuvant properties. Here we cloned the eltAB genes that encode LT and purified LT. Further testing and comparisons between the holotoxins (both subunits) and the B-subunits, such as how they similarly modulate the immune system, is needed to give evidence into potential adjuvant activity for use as preventatives against Salmonella and ETEC. These studies will also increase our understanding of how these toxins contribute to infection and pathogenesis.