Cloning and characterization of a male-specific defensin-like antimicrobial peptide from the tick Haemaphysalis longicornis

A novel gene was identified from a cDNA library of the male accessory glands of Haemaphysalis longicornis. The full-length cDNA of the gene was 349 bp, encoding a 79-amino acid defensin-like protein and therefore the protein was named HIMS-defensin. Reverse transcriptase-PCR results suggested that this gene was expressed exclusively in male ticks. The tissue expression pattern and the mRNA levels of HIMS-defensin during blood feeding were determined using real-time PCR. HIMS-defensin was expressed predominately in the male accessory gland and was up-regulated during blood feeding. The antimicrobial activity of a synthetic peptide based on the predicted mature portion of HIMS-defensin was examined against a variety of Gram-positive and Gram-negative bacteria and fungi. It appears that ticks use the antimicrobial peptide to protect their reproductive tracts from microbial infections. The protective role of HIMS-defensin during mating was also discussed. (C) 2011 Elsevier Ltd. All rights reserved.