The invention relates to an isolated protein for use as an antimicrobial agent comprises a plurality of LRR (leucine rich repeat) domains, each LRR domain independently comprising an amino acid sequence of formula (I): (F1LxxLxL(xxZ)YF2) wherein: F1 and F2 are independently, a contiguous amino acid sequence of between 1 and 30 residues; x can be any amino acid; L can be Leu, Ile, Val or Phe; Z can be NxL or CxxL; N is Asn, Thr, Ser or Cys; C is Cys or Ser; and Y=0 or 1.