Molecular characterization of a defensin gene from a hard tick,Dermacentor silvarum

Background: ticks are distributed worldwide and considered as vectors of many human diseases. tick defensins,a family of antimicrobial peptides,form the first line of defense against pathogens. findings: a defensin-like gene,named ds-defensin,was identified from a cdna library of the hard tick dermacentor silvarum collected from northeast china. the full-length cdna of ds-defensin was 225 bp,encoding a 74 amino acid peptide. the nucleotide sequence of ds-defensin shared 98.2% similarity to putative defensin from dermacentor marginatus. rt-pcr results suggested that ds-defensin was extensively expressed in tick salivary gland and midgut,with a higher expression level in midgut. ds-defensin showed broad antimicrobial activity against various gram-positive and gram-negative bacteria,as well as the fungus candida albicans. conclusions: we characterized a functional defensin from d. silvarum of china. ds-defensin showed bactericidal activity against various gram-positive and gram-negative bacteria. ds-defensin can be expected to be introduced to the medical field as a new molecule with antibacterial activity. © 2015 wang et al.; licensee biomed central.