Advertisement

Proteases in Blood-Feeding Nematodes and Their Potential as Vaccine Candidates

  • David Knox
Chapter
Part of the Advances in Experimental Medicine and Biology book series (AEMB, volume 712)

Abstract

Parasitic nematodes express and secrete a variety of proteases which they use for many purposes including the penetration of host tissues, digestion of host protein for nutrients, evasion of host immune responses and for internal processes such as tissue catabolism and apoptosis. For these broad reasons they have been examined as possible parasite control targets. Blood-feeding nematodes such as the barber-pole worm Haemonchus contortus that infect sheep and goats and the hookworms, Ancylostoma spp. and Necator americanus, affecting man, use an array of endo- and exopeptidases to digest the blood meal. Haemoglobin digestion occurs by an ordered and partly conserved proteolytic cascade. These proteases are accessible to host immune responses which can block enzyme function and lead to parasite expulsion and/or death. Thus they are receiving attention as components of vaccines against several parasitic nematodes of social and economic importance.

Keywords

Cysteine Protease Aspartyl Protease Haemonchus Contortus Reduce Worm Burden Necator Americanus 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Preview

Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.

References

  1. 1.
    Halton D. Nutritional adaptations to parasitism within the platyhelminthes. Int J Parasitol 1997; 27:693–704.PubMedCrossRefGoogle Scholar
  2. 2.
    Thorson RE. Studies on the mechanism of immunity in the rat to the nematode, Nippostrongylus muris. Am J Hyg 1953; 58:1–15.PubMedGoogle Scholar
  3. 3.
    Thorson RE. Effect of immune serum from rats on infective larvae of Nippostrongylus muris. Exp Parasitol 1954; 3:9–15.PubMedCrossRefGoogle Scholar
  4. 4.
    Rhorson RE. Proteolytic activity in extracts of the esophagus of adults of ancylostoma caninum and the effect of immune serum on this activity. J Parasitol 1956; 42:21–25.CrossRefGoogle Scholar
  5. 5.
    Thorson RE. The stimulation of acquired immunity in dogs by injections of extracts of the esophagus of adult hookworms. J Parasitol 1956b; 42:501–504.PubMedCrossRefGoogle Scholar
  6. 6.
    Williamson A, Lecchi P, Turk BE et al. A multi-enzyme cascade of hemoglobin proteolysis in the intestine of blood-feeding hookworms. J Biol Chem 2003; 279:35950–35957.CrossRefGoogle Scholar
  7. 7.
    Timms AR, Bueding E. Studies of a proteolytic enzyme from Schistosoma mansoni. Br J Pharmacol Chemother 1959; 14:68–73.PubMedGoogle Scholar
  8. 8.
    Knox DP, Jones, DG. Studies on the presence and release of proteolytic enzymes (proteinases)in gastro-intestinal nematodes of ruminants. Int J Parasitol 1990; 20:243–249.PubMedCrossRefGoogle Scholar
  9. 9.
    Cox GN, Pratt D, Hageman R et al. Molecular cloning and primary sequence of a cysteine protease expressed by Haemonchus contortus adult worms. Mol Biochem Parasitol 1990; 41:25–34.PubMedCrossRefGoogle Scholar
  10. 10.
    Pratt D, Cox GN, Milhausen MJ et al. A developmentally regulated cysteine protease gene family in Haemonchus contortus. Mol Biochem Parasitol 1990; 43:181–191.PubMedCrossRefGoogle Scholar
  11. 11.
    Pratt D, Armes LG, Hageman R et al. Cloning and sequence comparisons of four distinct cysteine proteases expressed by Haemonchus contortus adult worms. Mol Biochem Parasitol 1992; 51:209–218.PubMedCrossRefGoogle Scholar
  12. 12.
    Boisvenue RJ, Stiff MI, Tonkinson LV et al. Fibrinogen-degrading proteins from Haemonchus contortus used to vaccinate sheep. Am J Vet Res 1992; 53:1263–1265.PubMedGoogle Scholar
  13. 13.
    Knox DP, Redmond DL, Jones DG. Characterization of proteinases in extracts of adult Haemonchus contortus, the ovine abomasal nematode. Parasitology 1993; 106:395–404.PubMedCrossRefGoogle Scholar
  14. 14.
    Fetterer RH, Rhoads ML. The in vitro uptake and incorporation of hemoglobin by adult Haemonchus-contortus. Vet Parasitol 1997; 69:77–87.PubMedCrossRefGoogle Scholar
  15. 15.
    Willadsen P, Kemp DH. Vaccination with ‘concealed’ antigens for tick control. Parasitol Today 1988 J; 4:196–198.PubMedCrossRefGoogle Scholar
  16. 16.
    Munn EA, Greenwood CA, Coadwell WJ. Vaccination of young lambs by means of a protein fraction extracted from adult Haemonchus contortus. Parasitology 1987; 94:385–397.PubMedCrossRefGoogle Scholar
  17. 17.
    Munn EA. A helical, polymeric extracellular protein associated with the luminal surface of Haemonchus contortus intestinal cells. Tissue Cell 1977; 9:23–34.PubMedCrossRefGoogle Scholar
  18. 18.
    Newton SE, Munn EA. The development of vaccines against gastrointestinal nematode parasites, particularly Haemonchus contortus. Parasitol Today 1999; 15:116–122.PubMedCrossRefGoogle Scholar
  19. 19.
    Smith SK, Smith WD. Immunisation of sheep with an integral membrane glycoprotein complex of Haemonchus contortus and with its major polypeptide components. Res Vet Sci 1996; 60:1–6.PubMedCrossRefGoogle Scholar
  20. 20.
    LeJambre LF, Windon RG, Smith WD. Vaccination against Haemonchus contortus: performance of native parasite gut membrane glycoproteins in Merino lambs grazing contaminated pasture. Vet Parasitol 2008; 153:302–312.PubMedCrossRefGoogle Scholar
  21. 21.
    Munn EA, Smith TS, Smith H et al. Vaccination against Haemonchus contortus with denatured forms of the protective antigen H11. Parasite Immunol 1997; 19:243–248.PubMedCrossRefGoogle Scholar
  22. 22.
    Smith TS, Graham M, Munn EA et al. Cloning and characterization of a microsomal aminopeptidase from the intestine of the nematode Haemonchus contortus. Biochim Biophys Acta 1997; 1338:295–306.PubMedCrossRefGoogle Scholar
  23. 23.
    Haslam SM, Coles GC, Munn EA et al. Haemonchus contortus glycoproteins contain N-linked oligosaccharides with novel highly fucosylated core structures. J Biol Chem 1996; 271:30561–30570.PubMedCrossRefGoogle Scholar
  24. 24.
    Smith WD, Smith SK, Murray JM. Protection studies with integral membrane fractions of Haemonchus contortus. Parasite Immunol 1994; 16:231–241.PubMedCrossRefGoogle Scholar
  25. 25.
    Longbottom D, Redmond DL, Russell M et al. Molecular cloning and characterisation of a putative aspartyl proteinase associated with a gut membrane protein complex from adult Haemonchus contortus. Mol Biochem Parasitol 1997; 88:63–72.PubMedCrossRefGoogle Scholar
  26. 26.
    Redmond DL, Knox DP, Newlands G et al. Molecular cloning and characterisation of a developmentally regulated putative metallopeptidase present in a host protective extract of Haemonchus contortus. Mol Biochem Parasitol 1997; 85:77–87.PubMedCrossRefGoogle Scholar
  27. 27.
    Smith SK, Pettit D, Newlands GF et al. Further immunization and biochemical studies with a protective antigen complex from the microvillar membrane of the intestine of Haemonchus contortus. Parasite Immunol 1999; 21:187–199.PubMedCrossRefGoogle Scholar
  28. 28.
    Newlands GF, Skuce PJ, Knox DP et al. Cloning and characterization of a beta-galactoside-binding protein (galectin) from the gut of the gastrointestinal nematode parasite Haemonchus contortus. Parasitology 1999; 119:483–490.PubMedCrossRefGoogle Scholar
  29. 29.
    Skuce PJ, Newlands GF, Stewart EM et al. Cloning and characterisation of thrombospondin, a novel multidomain glycoprotein found in association with a host protective gut extract from Haemonchus contortus. Mol Biochem Parasitol 2001; 117:241–244.PubMedCrossRefGoogle Scholar
  30. 30.
    Newlands GF, Skuce PJ, Nisbet AJ et al. Molecular characterization of a family of metalloendopeptidases from the intestinal brush border of Haemonchus contortus. Parasitology 2006; 133:357–368.PubMedCrossRefGoogle Scholar
  31. 31.
    Smith WD, Smith SK, Pettit D et al. Relative protective properties of three membrane glycoprotein fractions from Haemonchus contortus. Parasite Immunol 2000; 22:63–71.PubMedCrossRefGoogle Scholar
  32. 32.
    Smith WD, Newlands GF, Smith SK et al. Metalloendopeptidases from the intestinal brush border of Haemonchus contortus as protective antigens for sheep. Parasite Immunol 2003; 25:313–323.PubMedCrossRefGoogle Scholar
  33. 33.
    Smith WD, Skuce PJ, Newlands GF et al. Aspartyl proteases from the intestinal brush border of Haemonchus contortus as protective antigens for sheep. Parasite Immunol 2003; 25:521–530.PubMedCrossRefGoogle Scholar
  34. 34.
    Rredmond DL, Geldhof P, Knox DP. Evaluation of Caenorhabditis elegans glycoproteins as protective immunogens against Haemonchus contortus challenge in sheep. Int J Parasitol 2004; 34:1347–1353.CrossRefGoogle Scholar
  35. 35.
    Jasmer DP, Mitreva MD, McCarter JP. mRNA sequences for Haemonchus contortus intestinal cathepsin B-like cysteine proteases display an extreme in abundance and diversity compared with other adult mammalian parasitic nematodes. Mol Biochem Parasitol 2004; 137:297–305.PubMedCrossRefGoogle Scholar
  36. 36.
    Ranjit N, Jones MK, Stenzel DJ et al. A survey of the intestinal transcriptomes of the hookworms, Necator americanus and Ancylostoma caninum, using tissues isolated by laser microdissection microscopy. Int J Parasitol 2006; 36:701–710.PubMedCrossRefGoogle Scholar
  37. 37.
    Ranjit N, Zhan B, Stenzel DJ et al. A family of cathepsin B cysteine proteases expressed in the gut of the human hookworm, Necator americanus. Mol Biocheml Parasitol 2008; 160:90–99.CrossRefGoogle Scholar
  38. 38.
    Knox DP, Smith SK, Smith WD. Immunization with an affinity purified protein extract from the adult parasite protects lambs against infection with Haemonchus contortus. Parasite Immunol 1999;21:201–210.PubMedCrossRefGoogle Scholar
  39. 39.
    Redmond DL, Knox DP. Protection studies in sheep using affinity-purified and recombinant cysteine proteinases of adult Haemonchus contortus. Vaccine 2004; 22:4252–4261.PubMedCrossRefGoogle Scholar
  40. 40.
    Skuce PJ, Redmond DL, Liddell S et al. Molecular cloning and characterization of gut-derived cysteine proteinases associated with a host protective extract from Haemonchus contortus. Parasitology 1999; 119:405–412.PubMedCrossRefGoogle Scholar
  41. 41.
    Redmond DL, Knox DP. Protection studies in sheep using affinity-purified and recombinant cysteine proteinases of adult Haemonchus contortus. Vaccine 2004; 22:4252–4261.PubMedCrossRefGoogle Scholar
  42. 42.
    Redmond DL, Knox DP. Further protection studies using recombinant forms of Haemonchus contortus cysteine proteinases. Parasite Immunol 2006; 28:213–219.PubMedCrossRefGoogle Scholar
  43. 43.
    Karanu FN, Rurangirwa FR, McGuire TC et al. Haemonchus contortus: identification of proteases with diverse characteristics in adult worm excretory-secretory products. Exp Parasitol 1993; 77:362–371.PubMedCrossRefGoogle Scholar
  44. 44.
    Karanu FN, Rurangirwa FR, McGuire TC et al. Haemonchus contortus: inter-and intrageographic isolate heterogeneity of proteases in adult worm excretory-secretory products. Exp Parasitol 1997; 86:89–91.PubMedCrossRefGoogle Scholar
  45. 45.
    Shompole S, Jasmer DP. Cathepsin B-like cysteine proteases confer intestinal cysteine protease activity in Haemonchus contortus. J Biol Chem 2001:276:2928–2934.PubMedCrossRefGoogle Scholar
  46. 46.
    Ruiz A, Molina JM, Njue A et al. Genetic variability in cysteine protease genes of Haemonchus contortus. Parasitology 2004; 128:549–559.PubMedCrossRefGoogle Scholar
  47. 47.
    Rehman A, Jasmer DP. Defined characteristics of cathepsin B-like proteins from nematodes: inferred functional diversity and phylogenetic relationships. Mol Biochem Parasitol 1999; 102:297–310.PubMedCrossRefGoogle Scholar
  48. 48.
    Jasmer DP, Mitreva MD, McCarter JP. mRNA sequences for Haemonchus contortus intestinal cathepsin B-like cysteine proteases display an extreme in abundance and diversity compared with other adult mammalian parasitic nematodes. Mol Biochem Parasitol 2004; 137:297–305.PubMedCrossRefGoogle Scholar
  49. 49.
    Yatsuda AP, Bakker N, Krijgsveld J et al. Identification of secreted cysteine proteases from the parasitic nematode Haemonchus contortus detected by biotinylated inhibitors. Infect Immun 2006; 74:1989–1993.PubMedCrossRefGoogle Scholar
  50. 50.
    Bakker N, Vervelde L, Kanobana K et al. Vaccination against the nematode Haemonchus contortus with a thiol-binding fraction from the excretory/secretory products (ES). Vaccine 2004; 22:618–628.PubMedCrossRefGoogle Scholar
  51. 51.
    De Vries E, Bakker N, Krijgsveld J et al. An AC-5 cathepsin B-like protease purified from Haemonchus contortus excretory secretory products shows protective antigen potential for lambs. Vet Res 2009; 40:41.PubMedCrossRefGoogle Scholar
  52. 52.
    Baig S, Damian RT, Peterson DS. A novel cathepsin B active site motif is shared by helminth bloodfeeders. Exp Parasitol 2002; 101:83–89.PubMedCrossRefGoogle Scholar
  53. 53.
    Larminie CG, Johnstone IL. Isolation and characterization of four developmentally regulated cathepsin B-like cysteine protease genes from the nematode Caenorhabditis elegans. DNA Cell Biol 1996; 15:75–82.PubMedCrossRefGoogle Scholar
  54. 54.
    Jasmer DP, Roth J, Myler PJ. Cathepsin B-like cysteine proteases and Caenorhabditis elegans homologues dominate gene products expressed in adult Haemonchus contortus intestine. Mol Biochem Parasitol 2001; 116:159–169.PubMedCrossRefGoogle Scholar
  55. 55.
    Geldhof P, Molloy C, Knox DP. Combinatorial RNAi on intestinal cathepsin B-like proteinases in Caenorhabditis elegans questions the perception of their role in nematode biology. Mol Biochem Parasitol 2006; 145:128–132.PubMedCrossRefGoogle Scholar
  56. 56.
    Dalton JP, Brindley PJ, Donnelly S et al. The enigmatic asparaginyl endopeptidase of helminth parasites. Trends Parasitol 2009; 25:59–61.PubMedCrossRefGoogle Scholar
  57. 57.
    Oliver EM, Skuce PJ, McNair CM et al. Identification and characterization of an asparaginyl proteinase (legumain) from the parasitic nematode, Haemonchus contortus. Parasitology 2006; 133:237–244.PubMedCrossRefGoogle Scholar
  58. 58.
    Geldhof P, Knox D. The intestinal contortin structure in Haemonchus contortus: an immobilised Anticoagulant? Int J Parasitol 2008; 38:1579–1588CrossRefGoogle Scholar
  59. 59.
    Pratt D, Boisvenue RJ, Cox GN. Isolation of putative cysteine protease genes of Ostertagia ostertagi. Mol Biochem Parasitol 1992; 56:39–48.PubMedCrossRefGoogle Scholar
  60. 60.
    Geldhof P, Claerebout E, Knox D et al. Vaccination of calves against Ostertagia ostertagi with cysteine proteinase enriched protein fractions. Parasite Immunol 2002; 24:263–270.PubMedCrossRefGoogle Scholar
  61. 61.
    Meyvis Y, Geldhof P, Gevaert K et al. Vaccination against ostertagia ostertagi with subfractions of the protective ES-thiol fraction. Vet Parasitol 2007; 149:239–245.PubMedCrossRefGoogle Scholar
  62. 62.
    Thorson RE. Proteolytic activity in extracts of the esophagus of adults of Ancylostoma caninum and the effect of immune serum on this activity. J Parasitol 1956:42:21–25.PubMedCrossRefGoogle Scholar
  63. 63.
    Eiff JA. Nature of an Anticoagulant from the cephalic glands of Ancylostoma caninum. J Parasitol 1966; 52:833–843.PubMedCrossRefGoogle Scholar
  64. 64.
    Spellman GG Jr, Nossel HL Anticoagulant activity of dog hookworm. Am J Physiol 1971; 220:922–927.PubMedGoogle Scholar
  65. 65.
    Hotez PJ, Cerami A. Secretion of a proteolytic Anticoagulant by Ancylostoma hookworms. J Exp Med 1983; 157:1594–1603.PubMedCrossRefGoogle Scholar
  66. 66.
    Hotez PJ, Trang NL, McKerrow JH et al. Isolation and characterization of a proteolytic enzyme from the adult hookworm Ancylostoma caninum. J Biol Chem 1985; 260:7343–7348.PubMedGoogle Scholar
  67. 67.
    Hawdon JM, Jones BF, Perregaux MA et al. Ancylostoma caninum: metalloprotease release coincides with activation of infective larvae in vitro. Exp Parasitol 1995; 80:205–211.PubMedCrossRefGoogle Scholar
  68. 68.
    Hotez P, Haggerty J, Hawdon J et al. Metalloproteases of infective Ancylostoma hookworm larvae and their possible functions in tissue invasion and ecdysis. Infect Immun 1990; 58:3883–3892.PubMedGoogle Scholar
  69. 69.
    Kumar S, Pritchard DI Secretion of metalloproteases by living infective larvae of Necator americanus. J Parasitol 1992; 78:917–919.PubMedCrossRefGoogle Scholar
  70. 70.
    Culley FJ, Brown A, Conroy DM et al. Eotaxin is specifically cleaved by hookworm metalloproteases preventing its action in vitro and in vivo. J Immunol 2000; 165:6447–6453.PubMedGoogle Scholar
  71. 71.
    Dowd AJ, Dalton JP, Loukas AC et al. Secretion of cysteine proteinase activity by the zoonotic hookworm Ancylostoma caninum. Am J Trop Med Hyg 1994; 51:341–347.PubMedGoogle Scholar
  72. 72.
    Harrop SA, Sawangjaroen N, Prociv P et al. Characterization and localization of cathepsin B proteinases expressed by adult Ancylostoma caninum hookworms. Mol Biochem Parasitol 1995; 71:163–171.PubMedCrossRefGoogle Scholar
  73. 73.
    Brinkworth RI, Brindley PJ, Harrop SA. Structural analysis of the catalytic site of AcCP-1, a cysteine proteinase secreted by the hookworm Ancylostoma caninum. Biochim Biophys Acta 1996:1298:4–8.PubMedCrossRefGoogle Scholar
  74. 74.
    Loukas A, Bethony JM, Williamson AL et al. Vaccination of dogs with a recombinant cysteine protease from the intestine of canine hookworms diminishes the fecundity and growth of worms. J Infect Dis 2004; 189:1952–1961.PubMedCrossRefGoogle Scholar
  75. 75.
    Ranjit N, Zhan B, Stenzel DJ et al. A family of cathepsin B cysteine proteases expressed in the gut of the human hookworm, Necator americanus. Mol Biochem Parasitol 2008; 160:90–99.PubMedCrossRefGoogle Scholar
  76. 76.
    Hotez PJ, Ashcom J, Zhan B et al. Effect of vaccination with a recombinant fusion protein encoding an astacinlike metalloprotease (MtP-1) secreted by host-stimulated Ancylostoma caninum third-stage infective larvae. J Parasitol 2003; 89:853–855.PubMedCrossRefGoogle Scholar
  77. 77.
    Loukas A, Bethony JM, Mendez S et al. Vaccination with recombinant aspartic hemoglobinase reduces parasite load and blood loss after hookworm infection in dogs. PloS Med 2005; 2:e295.PubMedCrossRefGoogle Scholar
  78. 78.
    Pearson MS, Bethony JM, Pickering DA et al. An enzymatically inactivated hemoglobinase from Necator americanus induces neutralizing antibodies against multiple hookworm species and protects dogs against heterologous hookworm infection. FASEB J 2009; 23:3007–3019.PubMedCrossRefGoogle Scholar
  79. 79.
    Pearson MS, Pickering DA, Tribolet L et al. Neutralizing antibodies to the hookworm hemoglobinase Na-APR-1: implications for a multivalent vaccine against hookworm infection and schistosomiasis. J Infect Dis 2010; 201:1561–1569.PubMedCrossRefGoogle Scholar
  80. 80.
    Hotez PJ, Bethony JM, Oliveira SC et al. A. Multivalent anthelminthic vaccine to prevent hookworm and schistosomiasis. Exp Rev Vaccines 2008; 7:745–752.CrossRefGoogle Scholar
  81. 81.
    Jones BF, Hotez PJ. Molecular cloning and characterization of Ac-mep-1, a developmentally regulated gut luminal metalloendopeptidase from adult Ancylostoma caninum hookworms. Mol Biochem Parasitol 2002; 119:107–116.PubMedCrossRefGoogle Scholar
  82. 82.
    Williamson AL, Brindley PJ, Abbenante G et al. Cleavage of hemoglobin by hookworm cathepsin D aspartic proteases and its potential contribution to host specificity FASEB J 2002; 16:1458–1460.PubMedGoogle Scholar
  83. 83.
    Williamson AL, Brindley PJ, Abbenante G et al. Hookworm aspartic protease, Na-aPr-2, cleaves human hemoglobin and serum proteins in a host-specific fashion. J Infect Dis 2003; 187:484–494.PubMedCrossRefGoogle Scholar
  84. 84.
    Williamson AL, Brindley PJ, Loukas A. Hookworm cathepsin D aspartic proteases: contributing roles in the host-specific degradation of serum proteins and skin macromolecules. Parasitology 2003; 126:179–185.PubMedCrossRefGoogle Scholar
  85. 85.
    Gluzman IY, Francis SE, Oksman A et al. Order and specificity of the Plasmodium falciparum hemoglobin degradation pathway. J Clin Invest 1994; 93:1602–1608.PubMedCrossRefGoogle Scholar
  86. 86.
    Ranjit N, Zhan B, Hamilton B et al. Proteolytic degradation of hemoglobin in the intestine of the human hookworm Necator americanus. J Infect Dis 2009; 199:904–912.PubMedCrossRefGoogle Scholar
  87. 87.
    Zhan B, Hotez PJ, Wang Y et al. A developmentally regulated metalloprotease secreted by host-stimulated Ancylostoma caninum third-stage infective larvae is a member of the astacin family of proteases. Mol Biochem Parasitol 2002; 120:291–296.PubMedCrossRefGoogle Scholar
  88. 88.
    Bond JS, Beynon RJ. The astacin family of metalloendopeptidases. Protein Sci 1995; 4:1247–1261.PubMedCrossRefGoogle Scholar
  89. 89.
    Hotez PJ, Ashcom J, Zhan B et al. Effect of vaccination with a recombinant fusion protein encoding an astacin-like metalloprotease (MTP-1) secreted by host-stimulated Ancylostoma caninum third-stage infective larvae. J Parasitol 2003; 89:853–855.PubMedCrossRefGoogle Scholar
  90. 90.
    Mendez S, Zhan B, Goud G et al. Effect of combining the larval antigens Ancylostoma secreted protein 2 (ASP-2) and metalloprotease 1 (MtP-1) in protecting hamsters against hookworm infection and disease caused by Ancylostoma ceylanicum. Vaccine 2005; 23:3123–3130.PubMedCrossRefGoogle Scholar
  91. 91.
    Feng J, Zhan B, Liu Y et al. Molecular cloning and characterization of Ac-MTP-2, an astacin-like metalloprotease released by adult Ancylostoma caninum. Mol Biochem Parasitol 2007; 152:132–138.PubMedCrossRefGoogle Scholar
  92. 92.
    Coyne CP, Brake D. Characterisation of Haemonchus contortus-derived cell populations propagated in vitro in a tissue culture environment and their potential to induce protective immunity in sheep. Int J Parasitol 2001; 31:359–376.PubMedCrossRefGoogle Scholar
  93. 93.
    Cachat E, Newlands GF, Ekoja SE et al. Attempts to immunize sheep against Haemonchus contortus using a cocktail of recombinant proteases derived from the protective antigen, H-gal-GP. Parasite Immunol 2010; 32:414–419.PubMedCrossRefGoogle Scholar
  94. 94.
    Murray L, Geldhof P, Clark D et al. Expression and purification of an active cysteine protease of Haemonchus contortus using caenorhabditis elegans. Int J Parasitol 2007; 37:1117–1125.PubMedCrossRefGoogle Scholar
  95. 95.
    Villa-Mancera A, Quiroz-Romero H, Correa D et al. Induction of immunity in sheep to Fasciola hepatica with mimotopes of cathepsin L selected from a phage display library. Parasitology 2008; 135:1437–1445.PubMedCrossRefGoogle Scholar
  96. 96.
    Kamath RS, Ahringer J. Genome-wide RNAi screening in Caenorhabditis elegans. Methods 2003; 30:313–321.PubMedCrossRefGoogle Scholar
  97. 97.
    Geldhof P, Murray L, Couthier A et al. Testing the efficacy of RNA interference in Haemonchus contortus. Int J Parasitol 2006; 36:801–810.PubMedCrossRefGoogle Scholar

Copyright information

© Landes Bioscience and Springer Science+Business Media, LLC 2011

Authors and Affiliations

  • David Knox
    • 1
  1. 1.Moredun Research InstitutePentlands Science ParkMidlothianUK

Personalised recommendations