A recombinant adenovirus that directs secretion of biologically active κ-bungarotoxin from mammalian cells

A novel Cre-lox system was used to construct an adenovirus encoding κ-bungarotoxin (κ-Bgt), modified to be secreted by attachment of a bovine prolactin signal sequence at the N-terminus of the toxin. Western blot of medium from HEK-293 cells infected with the virus demonstrated that recombinant κ-Bgt (R-κ-Bgt) was secreted. The biological activity of the secreted R-κ-Bgt was investigated in Xenopus oocytes that expressed neuronal nicotinic acetylcholine receptor (nAChR) subtypes α3β2 and α2β2. The recombinant toxin inhibited the response of α3β2 type AChRs to ACh, but did not inhibit the response of α2β2 type AChRs. These data demonstrated that the recombinant adenovirus directs the secretion of biologically active κ-Bgt from a mammalian cell line. Because adenovirus can be used to infect post-mitotic cells, recombinant adenoviruses encoding biologically active peptides may be of use as delivery vehicles for in vivo experiments where repeated application of the purified peptide is unfeasible.