Identification and characterization of a cDNA encoding the acetylcholinesterase of Haematobia irritans (L.) (Diptera: Muscidae) †

A 2217-nucleotide cDNA presumptively encoding acetylcholmesterase (AChE) of the horn fly, Haematobia irritans (L.) was sequenced. The open reading frame (ORF) encoded a 91 amino acid secretion signal peptide and a 613 amino acid mature protein with 95% identity and 98% similarity to the AChE of Musca domestica (L.). Structural features characteristic of the M. domestica and Drosophila melanogaster AChEs are conserved in the H. irritans AChE. The M. domestica and D. melanogaster AChEs are target sites for organophosphate inhibition as previously shown (Walsh et al. 2001. Biochem. J. 359: 175–181, Kozaki et al. 2002. Appl. Entomol. Zool. 37: 213–218), suggesting that this H. irritans AChE2 may be the target site for organophosphate.