The transcript sequence of the Amblyomma americanum Linnaeus (Acari: Ixodidae) defensin, termed amercin (amn), was ascertained and a 219-bp amn coding region identified. The gene encodes a 72-amino acid prepropeptide with a putative 37-amino acid mature peptide. This gene shows little similarity to either of the defensins from Amblyomma hebraeum Koch, the only other Amblyomma species for which ...

Antimicrobial peptides are major components of the innate immune response of epithelial cells. In insect vectors, these peptides may play a role in the control of gut pathogens. We have analyzed antimicrobial peptides produced by the sand fly Phlebotomus duboscqi, after challenge by injected bacteria or feeding with bacteria or the protozoan parasite Leishmania major. A new hemolymph peptide wi...

Defensin attack! Here we report the screening of human defensin 5 against the Keio Collection of E. coli strains. The results of this screen further our understanding of how this important hostdefense peptide kills bacteria and how bacteria protect themselves against the attack from the human host.

We designed a retro-isomer and seven circularized "beta-tile" peptide analogs of a typical rabbit alpha-defensin, NP-1. The analogs retained defensin-like architecture after the characteristic end-to-end, Cys(3,31) (C I:C VI), alpha-defensin disulfide bond was replaced by a backbone peptide bond. The retro-isomer of NP-1 was as active as the parent compound, suggesting that overall topology and...

α-defensins are abundant antimicrobial peptides with broad, potent antibacterial, antifungal, and antiviral activities in vitro. Although their contribution to host defense against bacteria in vivo has been demonstrated, comparable studies of their antiviral activity in vivo are lacking. Using a mouse model deficient in activated α-defensins in the small intestine, we show that Paneth cell α-de...

Several bivalves, including mussels, suffered from mortalities particularly in summer. To look for the possible effect of environmental parameters on immune capacities, Mytilus galloprovincialis were collected monthly from August 2005 to July 2008 from the Palavas Laguna, French Mediterranean coast. Q-PCR was used to quantify the expression of three antimicrobial peptide genes (defensin, mytili...

Crohn's disease is a chronic, inflammatory disease of the intestinal mucosa. Although intestinal bacteria are implicated in disease pathogenesis, the etiology is still unclear. The main location of disease is the small intestine (ileum) and the colon. Ileal disease has been linked to a mutation in the NOD2 gene. Defensins are antimicrobial peptides and in the ileum, are mainly expressed in Pane...

Invasion of enterocytes by pathogenic microbes evokes both innate and adaptive immune responses, and microbial pathogens have developed strategies to overcome the initial host immune defense. beta-Defensins are potentially important endogenous antibiotic-like effectors of innate immunity expressed by intestinal epithelia. In this study, the interplay between the enteric protozoan parasite Crypt...

K-Ras mutant pancreatic cancer cells display intensive macropinocytosis, indicating that this process may be exploited in the design of anticancer targeted therapies. In this study, we constructed a macropinocytosis-oriented recombinantly tailored defensin (DF-HSA) which consists of human β-defensin-2 (DF) and human serum albumin (HSA). The macropinocytosis intensity and cytotoxicity of DF-HSA ...

The production of antimicrobial peptides (AMPs) is a major defense mechanism against pathogen infestation and of particular importance for insects relying exclusively on an innate immune system. Here, we report on the characterization of three AMPs from the carpenter ant Camponotus floridanus. Due to sequence similarities and amino acid composition these peptides can be classified into the cyst...