Activity of lytic peptides against intracellular Trypanosoma cruzi amastigotes in vitro and parasitemias in mice.
Three cecropin-like lytic peptides (DC-1, DC-2, and DC-2R) were synthesized with virtually no sequence homology with the natural compound (cecropin B) while retaining the charge distribution, amphipathic, and hydrophobic properties of the natural compound. A fourth analog (alpha-Pi) without these later properties, but a similar molecular weight, was also synthesized as a nonlytic peptide control. The 3 lytic peptides were examined for their ability to kill Trypanosoma cruzi trypomastigotes in vitro, intracellular amastigotes in vitro, and their toxicity to a mammalian cell line. DC-2 at 5 microM and DC-1 and DC-2R at 10 microM were 100% effective in killing T. cruzi trypomastigotes in vitro, suggesting at least a 10-fold increase in lytic activity over previous tested lytic peptide analogues, SB-37 and Shiva-1. When T. cruzi-infected Vero cells were treated with a single or double exposure of low concentrations (2.5 microM) of DC-1, DC-2, and DC-2R there was a significant (P < 0.05) reduction in amastigote numbers/cell when compared to untreated and alpha-Pi-treated T. cruzi-infected cells. Vero cells alone treated with the lytic peptides showed no reduction in number or toxicity. One of the peptides (DC-1) was tested for its toxicity in AJ mice and its ability to reduce parasitemias in T. cruzi-infected AJ mice. No untoward effects were seen in AJ mice injected intravenously with 50 micrograms/mouse daily for 10 days. There was a significant (P < 0.05) reduction in parasitemia and mortality by day 14 postinoculation (from 100% to 0%) in T. cruzi-infected AJ mice given 25 micrograms of DC-1/mouse on days 2, 4, 6, 8, and 10 postinoculation.
Department of Clinical Sciences, College of Veterinary Medicine, Cornell University, Ithaca, New York 14853, USA.
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Barr
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Jaynes
D000595:Amino Acid Sequence; D000818:Animals; D023181:Antimicrobial Cationic Peptides; D014355:Chagas Disease / Q000188:drug therapy*; D002522:Chlorocebus aethiops; D004305:Dose-Response Relationship, Drug; D007301:Insect Hormones / Q000737:chemistry*; D019476:Insect Proteins; D051379:Mice; D008969:Molecular Sequence Data; D018512:Parasitemia / Q000188:drug therapy*; D010455:Peptides / Q000627:therapeutic use* / Q000633:toxicity; D011994:Recombinant Proteins; D014344:Trypanocidal Agents / Q000627:therapeutic use* / Q000633:toxicity; D014349:Trypanosoma cruzi / Q000187:drug effects; D014709:Vero Cells
D023181:Antimicrobial Cationic Peptides; C097545:DC-1 peptide, synthetic; C097546:DC-2 peptide, recombinant; C097547:DC-2R peptide, recombinant; D007301:Insect Hormones; D019476:Insect Proteins; D010455:Peptides; D011994:Recombinant Proteins; D014344:Trypanocidal Agents; C031162:cecropin B protein, Insecta