Cecropins are a group of antimicrobial peptides which have bactericidal activity against a broad range of bacteria. To date, the cecropins used in a variety of studies were either purified from their natural source or obtained by chemical synthesis. The present study was conducted to test whether bactericidally active cecropins could be expressed in a fish cell line. For this purpose, Chinook salmon embryo cells (CHSE-214) were transfected with cecropin transgene constructs: Hyalophora cecropia preprocecropin B, procecropin B, cecropin B, and porcine P, cecropin. From the transfected cells, single cell clones were selected and screened for the presence of cecropin gene constructs by PCR amplification. The expression of the cecropin transgene in the PCR positive clones was determined by RT-PCR reaction. Southern blot hybridization results showed that the cecropin gene constructs were integrated into the genome in a multiple integration pattern. Bactericidal activity of the cecropins, synthesized from transgene constructs, was detected using inhibition zone assay for fish pathogenic bacteria: Aeromonas hydrophila, Pseudomonas fluorescens, and Vibrio anguillarum. Cecropin antimicrobial peptides produced in CHSE-214 cells possess bactericidal activity against these three fish pathogenic bacteria. (C) 2003 Elsevier Science B.V. All fights reserved.