Hostname: page-component-78c5997874-s2hrs Total loading time: 0 Render date: 2024-11-10T09:49:45.912Z Has data issue: false hasContentIssue false
  • English
  • Français

Developing a rapid throughput screen for detection of nematicidal activity of plant cysteine proteinases: the role of Caenorhabditis elegans cystatins

Published online by Cambridge University Press:  04 September 2013

A. M. PHIRI ,
D. DE POMERAI ,
D. J. BUTTLE  and
J. M. B. BEHNKE
A. M. PHIRI
Affiliation:
School of Biology, University of Nottingham, Nottingham, NG7 2RD, UK School of Veterinary Medicine, University of Zambia, Lusaka, Zambia
D. DE POMERAI
Affiliation:
School of Biology, University of Nottingham, Nottingham, NG7 2RD, UK
D. J. BUTTLE
Affiliation:
Department of Infection and Immunity, University of Sheffield Medical School, Sheffield, S10 2RX, UK
J. M. B. BEHNKE*
Affiliation:
School of Biology, University of Nottingham, Nottingham, NG7 2RD, UK
*
* Corresponding author: School of Biology, University of Nottingham, Nottingham NG7 2RD, UK. E-mail: Jerzy.behnke@nottingham.ac.uk
Get access Rights & Permissions [Opens in a new window]

Summary

Plant cysteine proteinases (CPs) from papaya (Carica papaya) are capable of killing parasitic nematode worms in vitro and have been shown to possess anthelmintic effects in vivo. The acute damage reported in gastrointestinal parasites has not been found in free-living nematodes such as Caenorhabditis elegans nor among the free-living stages of parasitic nematodes. This apparent difference in susceptibility might be the result of active production of cysteine proteinase inhibitors (such as cystatins) by the free-living stages or species. To test this possibility, a supernatant extract of refined papaya latex (PLS) with known active enzyme content was used. The effect on wild-type (Bristol N2) and cystatin null mutant (cpi-1−/− and cpi-2−/−) C. elegans was concentration-, temperature- and time-dependent. Cysteine proteinases digested the worm cuticle leading to release of internal structures and consequent death. Both cystatin null mutant strains were highly susceptible to PLS attack irrespective of the temperature and concentration of exposure, whereas wild-type N2 worms were generally resistant but far more susceptible to attack at low temperatures. PLS was able to induce elevated cpi-1 and cpi-2 cystatin expression. We conclude that wild-type C. elegans deploy cystatins CPI-1 and CPI-2 to resist CP attack. The results suggest that the cpi-1 or cpi-2 null mutants (or a double mutant combination of the two) could provide a cheap and effective rapid throughput C. elegans-based assay for screening plant CP extracts for anthelmintic activity.

Keywords

Plant cysteine proteinasespapaya latex supernatantanthelminticCaenorhabditis eleganscystatins
Type
Research Article
Information
Parasitology , Volume 141 , Issue 2 , February 2014 , pp. 164 - 180
Copyright
Copyright © Cambridge University Press 2013 

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

REFERENCES

Anbalagan, C., Lafayette, I., Antoniou-Kourounioti, M., Haque, M., King, J., Johnsen, B., Baillie, D., Gutierrez, C., Rodriguez Martin, J. and de Pomerai, D. (2012). Transgenic nematodes as biosensors for metal stress in soil pore water samples. Ecotoxicology 21, 439–455. doi: 10.1007/s10646-011-0804-0.CrossRefGoogle ScholarPubMed
Anderson, G. L., Boyd, W. A. and Williams, P. L. (2001). Assessment of sublethal endpoints for toxicity testing with the nematode Caenorhabditis elegans . Environmental Toxicology and Chemistry 20, 833–838. doi: 10.1002/etc.5620200419.CrossRefGoogle ScholarPubMed
Barrett, A. J., Rawlings, N. D. and Woessner, J. F. (1998). Handbook of Proteolytic Enzymes. Academic Press, London, UK.Google Scholar
Bartley, D. J., Jackson, F., Jackson, E. and Sargison, N. (2004). Characterisation of two triple resistant field isolates of Teladorsagia from Scottish lowland sheep farms. Veterinary Parasitology 123, 189–199. doi: 10.1016/j.vetpar.2004.06.018.CrossRefGoogle ScholarPubMed
Behnke, J. M., Buttle, D. J., Stepek, G., Lowe, A. and Duce, I. R. (2008). Developing novel anthelmintics from plant cysteine proteinases. Parasite and Vectors 1, 29. doi: 10.1186/1756-3305-1-29.CrossRefGoogle ScholarPubMed
Bethony, J., Brooker, S., Albonico, M., Geiger, S. M., Loukas, A., Diemert, D. and Hotez, P. J. (2006). Soil-transmitted helminth infections: ascariasis, trichuriasis, and hookworm. Lancet 367, 1521–1532. doi: 10.1016/s0140-6736(06)68653-4.CrossRefGoogle ScholarPubMed
Boyd, W. A., Cole, R. D., Anderson, G. L. and Williams, P. L. (2003). The effects of metals and food availability on the behavior of Caenorhabditis elegans . Environmental Toxicology and Chemistry 22, 3049–3055. doi: 10.1897/02-565.CrossRefGoogle ScholarPubMed
Boyd, W. A., McBride, S. J., Rice, J. R., Snyder, D. W. and Freedman, J. H. (2010). A high-throughput method for assessing chemical toxicity using a Caenorhabditis elegans reproduction assay. Toxicology and Applied Pharmacology 245, 153–159. doi: 10.1016/j.taap.2010.02.014.CrossRefGoogle ScholarPubMed
Buckingham, S. D. and Sattelle, D. B. (2009). Fast, automated measurement of nematode swimming (thrashing) without morphometry. BMC Neuroscience. 10, 84. doi: 10.1186/1471-2202-10-84.CrossRefGoogle ScholarPubMed
Burke, J. M., Wells, A., Casey, P. and Miller, J. E. (2009). Garlic and papaya lack control over gastrointestinal nematodes in goats and lambs. Veterinary Parasitology 159, 171–174. doi: 10.1016/j.vetpar.2008.10.021.CrossRefGoogle ScholarPubMed
Burns, A. R., Kwok, T. C. Y., Howard, A., Houston, E., Johanson, K., Chan, A., Cutler, S. R., McCourt, P. and Roy, P. J. (2006). High-throughput screening of small molecules for bioactivity and target identification in Caenorhabditis elegans . Nature Protocols 1, 1906–1914.CrossRefGoogle ScholarPubMed
Burns, A. R., Wallace, I. M., Wildenhain, J., Tyers, M., Giaever, G., Bader, G. D., Nislow, C., Cutler, S. R. and Roy, P. J. (2010). A predictive model for drug bioaccumulation and bioactivity in Caenorhabditis elegans . Nature Chemical Biology 6, 549–557. doi: 10.1038/nchembio.380.CrossRefGoogle ScholarPubMed
Buttle, D. J., Dando, P. M., Coe, P. F., Sharp, S. L., Shepherd, S. T. and Barrett, A. J. (1990). The preparation of fully active chymopapain free of contaminating proteinases. Biological Chemistry Hoppe-Seyler 371, 1083–1088.CrossRefGoogle ScholarPubMed
Buttle, D. J., Behnke, J. M., Bartley, Y., Elsheikha, H. M., Bartley, D. J., Garnett, M. C., Donnan, A. A., Jackson, F., Lowe, A. and Duce, I. R. (2011). Oral dosing with papaya latex is an effective anthelmintic treatment for sheep infected with Haemonchus contortus . Parasite and Vectors 15, 11. doi: 10.1186/1756-3305-4-36.Google Scholar
Caffrey, C. R. and Secor, W. E. (2011). Schistosomiasis: from drug deployment to drug development. Current Opinion in Infectious Diseases 24, 410–417. doi: 10.1097/QCO.0b013e328349156f.CrossRefGoogle ScholarPubMed
Caldwell, F. C. and Caldwell, E. L. (1929). A study of the anthelmintic efficiency of higuerolatex in the treatment of trichuriasis, with comment as to its effectiveness against ascaris infestation. American Journal of Tropical Medicine and Hygiene s1–9, 471–482.CrossRefGoogle Scholar
Cezar, A. S., Toscan, G., Camillo, G., Sangioni, L. A., Ribas, H. O. and Vogel, F. S. F. (2010). Multiple resistance of gastrointestinal nematodes to nine different drugs in a sheep flock in southern Brazil. Veterinary Parasitology 173, 157–160. doi: 10.1016/j.vetpar.2010.06.013.CrossRefGoogle Scholar
Crompton, D. W. T. and Nesheim, M. C. (2002). Nutritional impact of intestinal helminthiasis during the human life cycle. Annual Review of Nutrition 22, 35–59. doi: 10.1146/annurev.nutr.22.120501.134539.CrossRefGoogle ScholarPubMed
Cronin, C., Mendel, J., Mukhtar, S., Kim, Y., Stirbl, R., Bruck, J. and Sternberg, P. W. (2005). An automated system for measuring parameters of nematode sinusoidal movement. BMC Genetics 6, 5. doi: 10.1186/1471-2156-6-5.CrossRefGoogle ScholarPubMed
Daniells, C., Duce, I., Thomas, D., Sewell, P., Tattersall, J. and de Pomerai, D. (1998). Transgenic nematodes as biomonitors of microwave-induced stress. Mutation Research/Fundamental and Molecular Mechanisms of Mutagenesis 399, 55–64. doi: 10.1016/s0027-5107(97)00266-2.CrossRefGoogle ScholarPubMed
Dunn, W. A., Hubbard, A. L. and Aronson, N. N. (1980). Low temperature selectively inhibits fusion between pinocytic vesicles and lysosomes during heterophagy of 125I-asialofetuin by the perfused rat liver. Journal of Biological Chemistry 255, 5971–5978.CrossRefGoogle ScholarPubMed
Elliott, A. M., Kizza, M., Quigley, M. A., Ndibazza, J., Nampijja, M., Muhangi, L., Morison, L., Namujju, P. B., Muwanga, M., Kabatereine, N. and Whitworth, J. A. (2007). The impact of helminths on the response to immunization and on the incidence of infection and disease in childhood in Uganda: design of a randomized, double-blind, placebo-controlled, factorial trial of deworming interventions delivered in pregnancy and early childhood [ISRCTN32849447]. Clinical Trials 4, 42–57. doi: 10.1177/1740774506075248.CrossRefGoogle ScholarPubMed
Feng, Z., Cronin, C., Wittig, J. J., Sternberg, P. and Schafer, W. R. (2004). An imaging system for standardized quantitative analysis of C. elegans behavior. BMC Bioinformatics 115, 5. doi: 10.1186/1471-2105-5-115.Google Scholar
Fire, A. (1992). Histochemical techniques for locating Escherichia coli beta-galactosidase activity in transgenic organisms. Genetics Analysis Techniques and Applications 9, 151–158. doi: 10.1016/1050-3862(92)90042-4.Google ScholarPubMed
Geary, T. G. and Thompson, D. P. (2001). Caenorhabditis elegans: how good a model for veterinary parasites? Veterinary Parasitology 101, 371–386. doi: 10.1016/s0304-4017(01)00562-3.CrossRefGoogle Scholar
Geary, T. G., Sangster, N. C. and Thompson, D. P. (1999). Frontiers in anthelmintic pharmacology. Veterinary Parasitology 84, 275–295. doi: 10.1016/s0304-4017(99)00042-4.CrossRefGoogle ScholarPubMed
Geary, T. G., Woo, K., McCarthy, J. S., Mackenzie, C. D., Horton, J., Prichard, R. K., de Silva, N. R., Olliaro, P. L., Lazdins-Helds, J. K., Engels, D. A. and Bundy, D. A. (2010). Unresolved issues in anthelmintic pharmacology for helminthiases of humans. International Journal for Parasitology 40, 1–13. doi: 10.1016/j.ijpara.2009.11.001.CrossRefGoogle ScholarPubMed
Geerts, S. and Gryseels, B. (2000). Drug resistance in human helminths: current situation and lessons from livestock. Clinical Microbiology Reviews 13, 207–222. doi: 10.1128/cmr.13.2.207-222.2000.CrossRefGoogle ScholarPubMed
Githiori, J. B., Athanasiadou, S. and Thamsborg, S. M. (2006). Use of plants in novel approaches for control of gastrointestinal helminths in livestock with emphasis on small ruminants. Veterinary Parasitology 139, 308–320. doi: 10.1016/j.vetpar.2006.04.021.CrossRefGoogle ScholarPubMed
Guven, K., Duce, J. A. and de Pomerai, D. I. (1994). Evaluation of a stress-inducible transgenic nematode strain for rapid aquatic toxicity testing. Aquatic Toxicology 29, 119–137. doi: 10.1016/0166-445x(94)90052-3.CrossRefGoogle Scholar
Hammond, J. A., Fielding, D. and Bishop, S. C. (1997). Prospects for plant anthelmintics in tropical veterinary medicine. Veterinary Research Communications 21, 213–228. doi: 10.1023/a:1005884429253.CrossRefGoogle ScholarPubMed
Hashmi, S., Zhang, J., Oksov, Y., Ji, Q. and Lustigman, S. (2006). The Caenorhabditis elegans CPI-2a cystatin-like inhibitor has an essential regulatory role during oogenesis and fertilization. Journal of Biological Chemistry 281, 28415–28429. doi: 10.1074/jbc.M600254200.CrossRefGoogle ScholarPubMed
Hotez, P. J. and Kamath, A. (2009). Neglected tropical diseases in sub-Saharan Africa: review of their prevalence, distribution, and disease burden. PLoS Neglected Troical Diseases 3, e412. doi: 10.1371/journal.pntd.0000412.CrossRefGoogle ScholarPubMed
Hotez, P. J., Brindley, P. J., Bethony, J. M., King, C. H., Pearce, E. J. and Jacobson, J. (2008). Helminth infections: the great neglected tropical diseases. Journal of Clinical Investigation 118, 1311–1321. doi: 10.1172/JCI34261.CrossRefGoogle ScholarPubMed
Hotez, P. J., Fenwick, A., Savioli, L. and Molyneux, D. H. (2009). Rescuing the bottom billion through control of neglected tropical diseases. Lancet 373, 1570–1575. doi: 10.1016/s0140-6736(09)60233-6.CrossRefGoogle ScholarPubMed
Igarashi, R., Yoshinari, Y., Yokota, H., Sugi, T., Sugihara, F., Ikeda, K., Sumiya, H., Tsuji, S., Mori, I., Tochio, H., Harada, Y. and Shirakawa, M. (2012). Real-Ttme background-free selective imaging of fluorescent nanodiamonds in vivo . Nano Letters 12, 5726−5732. doi: 10.1021/nl302979d.CrossRefGoogle ScholarPubMed
Jonxis, J. H. and Bekius, H. (1953). The treatment of ascaris infection with velardon. Archives of Disease in Childhood 28, 329–331.CrossRefGoogle ScholarPubMed
Keiser, J. and Utzinger, J. (2008). Efficacy of current drugs against soil-transmitted helminth infections. Journal of the American Medical Association 299, 1937–1948. doi: 10.1001/jama.299.16.1937.Google ScholarPubMed
Keiser, J. and Utzinger, J. (2010). The drugs we have and the drugs we need against major helminth infections. In Advances in Parasitology (ed. Xiao-Nong Zhou, R. B. R. O. and Jürg, U.), pp. 197–230. Academic Press, London, UK.Google Scholar
Kimura, E. (2011). The Global Programme to Eliminate Lymphatic Filariasis: history and achievements with special reference to annual single-dose treatment with diethylcarbamazine in Samoa and Fiji. Tropical Medicine and Health 39, 17–30. doi: 10.2149/tmh.2010-18.CrossRefGoogle ScholarPubMed
Kiontke, K. C., Felix, M.-A., Ailion, M., Braendle, C., Penigault, J.-B. and Fitch, D. H. A. (2011). A phylogeny and molecular barcodes for Caenorhabditis, with numerous new species from rotting fruits. BMC Evolutionary Biology 11, 339.CrossRefGoogle ScholarPubMed
Kotze, A. C. (2012). Target-based and whole-worm screening approaches to anthelmintic discovery. Veterinary Parasitology 186, 118–123. doi: 10.1016/j.vetpar.2011.11.052.CrossRefGoogle ScholarPubMed
Kwok, T. C. Y., Ricker, N., Fraser, R., Chan, A. W., Burns, A., Stanley, E. F., McCourt, P., Cutler, S. R. and Roy, P. J. (2006). A small-molecule screen in C. elegans yields a new calcium channel antagonist. Nature 441, 91–95. doi: 10.1038/nature04657.CrossRefGoogle Scholar
Langerholc, T., Zavašnik-Bergant, V., Turk, B., Turk, V., Abrahamson, M. and Kos, J. (2005). Inhibitory properties of cystatin F and its localization in U937 promonocyte cells. FEBS Journal 272, 1535–1545. doi: 10.1111/j.1742-4658.2005.04594.x.CrossRefGoogle ScholarPubMed
Lans, C., Turner, N., Khan, T. and Brauer, G. (2007). Ethnoveterinary medicines used to treat endoparasites and stomach problems in pigs and pets in British Columbia, Canada. Veterinary Parasitology 148, 325–340. doi: 10.1016/j.vetpar.2007.06.014.CrossRefGoogle ScholarPubMed
Leathwick, D. M., Hosking, B. C., Bisset, S. A. and McKay, C. H. (2009). Managing anthelmintic resistance: is it feasible in New Zealand to delay the emergence of resistance to a new anthelmintic class? New Zealand Veterinary Journal 57, 181–192. doi: 10.1080/00480169.2009.36900.CrossRefGoogle ScholarPubMed
Lindblom, T. H. and Dodd, A. K. (2006). Xenobiotic detoxification in the nematode Caenorhabditis elegans . Journal of Experimental Zoology Part A: Comparative Experimental Biology 305A, 720–730. doi: 10.1002/jez.a.324.CrossRefGoogle Scholar
Luoga, W., Mansur, F., Buttle, D. J., Duce, I. R., Garnett, M. C. and Behnke, J. M. (2012). The anthelmintic efficacy of papaya latex in a rodent-nematode model is not dependent on fasting before treatment. Journal of Helminthology 86, 311–316. doi: 10.1017/S0022149X11000368.CrossRefGoogle Scholar
Maciel, S., Giménez, A. M., Gaona, C., Waller, P. J. and Hansen, J. W. (1996). The prevalence of anthelmintic resistance in nematode parasites of sheep in Southern Latin America: Paraguay. Veterinary Parasitology 62, 207–212. doi: 10.1007/s11250-011-9903-4.CrossRefGoogle ScholarPubMed
Maphosa, V. and Masika, P. J. (2012). Anthelmintic screening of fractions of Elephantorrhiza elephantina root extract against Haemonchus contortus . Tropical Animal Health and Production 44, 159–163. doi: 10.1007/s11250-011-9903-4.CrossRefGoogle ScholarPubMed
Miller, C. M., Waghorn, T. S., Leathwick, D. M., Candy, P. M., Oliver, A. M. B., and Watson, T. G. (2012). The production cost of anthelmintic resistance in lambs. Veterinary Parasitology 186, 376–381. doi: 10.1016/j.vetpar.2011.11.063.CrossRefGoogle ScholarPubMed
Molyneux, D. H., Bradley, M., Hoerauf, A., Kyelem, D. and Taylor, M. J. (2003). Mass drug treatment for lymphatic filariasis and onchocerciasis. Trends in Parasitology 19, 516–522. doi: 10.1016/j.pt.2003.09.004.CrossRefGoogle ScholarPubMed
Monici, M. (2005). Cell and tissue autofluorescence research and diagnostic applications. In Biotechnology Annual Review (ed. El-Gewely, M. R.). pp. 227–256. Elsevier, Amsterdam, the Netherlands. doi: 10.1016/S1387-2656(05)11007-2.Google Scholar
Murray, J., Manoury, B., Balic, A., Watts, C. and Maizels, R. M. (2005). Bm-CPI-2, a cystatin from Brugia malayi nematode parasites, differs from Caenorhabditis elegans cystatins in a specific site mediating inhibition of the antigen-processing enzyme AEP. Molecular and Biochemical Parasitology 139, 197–203. doi: 10.1016/j.molbiopara.2004.11.008.CrossRefGoogle Scholar
Mutwakil, M. H. A. Z., Steele, T. J. G., Lowe, K. C. and de Pomerai, D. I. (1997). Surfactant stimulation of growth in the nematode Caenorhabditis elegans . Enzyme and Microbial Technology 20, 462–470. doi:org/10.1016/S0141-0229(96)01173-8.CrossRefGoogle Scholar
Mwale, M. and Masika, P. (2009). Ethno-veterinary control of parasites, management and role of village chickens in rural households of Centane district in the Eastern Cape, South Africa. Tropical Animal Health and Production 41, 1685–1693. doi: 10.1007/s11250-009-9366-z.CrossRefGoogle ScholarPubMed
Nchu, F., Githiori, J. B., McGaw, L. J. and Eloff, J. N. (2011). Anthelmintic and cytotoxic activities of extracts of Markhamia obtusifolia Sprague (Bignoniaceae). Veterinary Parasitology 183, 184–188. doi: 10.1016/j.vetpar.2011.06.017.CrossRefGoogle ScholarPubMed
Nieuwhof, G. J. and Bishop, S. C. (2005). Costs of the major endemic diseases of sheep in Great Britain and the potential benefits of reduction in disease impact. Animal Science 81, 23–29. doi: 10.1079/ASC41010023.CrossRefGoogle Scholar
Power, R., David, H., Mutwakil, M., Fletcher, K., Daniells, C., Nowell, M., Dennis, J., Martinelli, A., Wiseman, R., Wharf, E. and de Pomerai, D. (1998). Stress-inducible transgenic nematodes as biomonitors of soil and water pollution. Journal of Biosciences 23, 513–526. doi: 10.1007/bf02936145.CrossRefGoogle Scholar
Prichard, R. K. (1990). Anthelmintic resistance in nematodes: extent, recent understanding and future directions for control and research. International Journal for Parasitology 20, 515–523. doi: 10.1016/0020-7519(90)90199-w.CrossRefGoogle ScholarPubMed
Reyburn, H., Mtove, G., Hendriksen, I. and Seidlein, L. V. (2009). Oral quinine for the treatment of uncomplicated malaria. Br Med J 339, b2066. doi: 10.1136/bmj.b2066.CrossRefGoogle ScholarPubMed
Riddle, D. L., Blumenthal, T., Meyer, B. J. and Priess, J. R. (1997). C. elegans II, 2nd Edn. Cold Spring Harbor Laboratory Press, Cold Spring Harbor, NY, USA.Google Scholar
Satrija, F., Nansen, P., Bjørn, H., Murtini, S. and He, S. (1994). Effect of papaya latex against Ascaris suum in naturally infected pigs. Journal of Helminthology 68, 343–346. doi: 10.1017/S0022149X00001619.CrossRefGoogle ScholarPubMed
Ségalat, L. (2006). Drug discovery: here comes the worm. ACS Chemical Biology 1, 277–278. doi: 10.1021/cb600221m.CrossRefGoogle ScholarPubMed
Simpkin, K. G. and Coles, G. C. (1981). The use of Caenorhabditis elegans for anthelmintic screening. Journal of Chemical Technology and Biotechnology 31, 66–69. doi: 10.1002/jctb.503310110.CrossRefGoogle Scholar
Sluder, A. E. and Baumeister, R. (2004). From genes to drugs: target validation in Caenorhabditis elegans. Drug Discovery Today: Technologies 1, 171–177. doi: 10.1016/j.ddtec.2004.09.007.CrossRefGoogle ScholarPubMed
Stepek, G., Behnke, J. M., Buttle, D. J. and Ducel, I. R. (2004). Natural plant cysteine proteinases as anthelmintics? Trends in Parasitology 20, 322–327. doi: 10.1016/j.pt.2004.05.003.CrossRefGoogle ScholarPubMed
Stepek, G., Buttle, D. J., Duce, I. R., Lowe, A. and Behnke, J. M. (2005). Assessment of the anthelmintic effect of natural plant cysteine proteinases against the gastrointestinal nematode, Heligmosomoides polygyrus, in vitro . Parasitology 130, 203–211. doi: 10.1017/s0031182004006225.CrossRefGoogle ScholarPubMed
Stepek, G., Buttle, D. J., Duce, I. R. and Behnke, J. M. (2006 a). Human gastrointestinal nematode infections: are new control methods required? International Journal of Experimental Pathology 87, 325–341. doi: 10.1111/j.1365-2613.2006.00495.x.CrossRefGoogle ScholarPubMed
Stepek, G., Lowe, A., Buttle, D., Duce, I. and Behnke, J. (2006 b). In vitro and in vivo anthelmintic efficacy of plant cysteine proteinases against the rodent gastrointestinal nematode, Trichuris muris . Parasitology 132, 681–689.CrossRefGoogle ScholarPubMed
Stepek, G., Lowe, A. E., Buttle, D. J., Duce, I. R. and Behnke, J. M. (2007 a). Anthelmintic action of plant cysteine proteinases against the rodent stomach nematode, Protospirura muricola, in vitro and in vivo . Parasitology 134, 103–112. doi: 10.1017/s0031182006001302.CrossRefGoogle ScholarPubMed
Stepek, G., Lowe, A. E., Buttle, D. J., Duce, I. R. and Behnke, J. M. (2007 b). The anthelmintic efficacy of plant-derived cysteine proteinases against the rodent gastrointestinal nematode, Heligmosomoides polygyrus, in vivo . Parasitology 134, 1409–1419. doi: 10.1017/s0031182007002867.CrossRefGoogle ScholarPubMed
Stepek, G., Lowe, A. E., Buttle, D. J., Duce, I. R. and Behnke, J. M. (2007 c). In vitro anthelmintic effects of cysteine proteinases from plants against intestinal helminths of rodents. Journal of Helminthology 81, 353–360. doi: 10.1017/s0022149×0786408x.CrossRefGoogle ScholarPubMed
Stransky, E. and Reyes, A. (1955). Ascariasis in the tropics: (with considerations on its treatment). Journal of Tropical Pediatrics 1, 174–187.CrossRefGoogle ScholarPubMed
Tagboto, S. and Townson, S. (2001). Antiparasitic properties of medicinal plants and other naturally occurring products. Advances in Parasitology 50, 199–295. doi: 10.1016/S0065-308X(01)50032-9.CrossRefGoogle ScholarPubMed
Taylor, S. and Berridge, V. (2006). Medicinal plants and malaria: an historical case study of research at the London School of Hygiene and Tropical Medicine in the twentieth century. Transactions of the Royal Society of Tropical Medicine and Hygiene 100, 707–714. doi: 10.1016/j.trstmh.2005.11.017.CrossRefGoogle ScholarPubMed
Utzinger, J., N'Goran, E. K., Caffrey, C. R. and Keiser, J. (2011). From innovation to application: social–ecological context, diagnostics, drugs and integrated control of schistosomiasis. Acta Tropica 120(Suppl 1), S121–S137. doi: 10.1016/j.actatropica.2010.08.020.CrossRefGoogle ScholarPubMed
van Wyk, J. A., Coles, G. C. and Tammi Krecek, R. C. (2002). Can we slow the development of anthelmintic resistance? An electronic debate. Trends in Parasitology 18, 336–337. doi: 10.1016/s1471-4922(02)02343-7.CrossRefGoogle ScholarPubMed
Varughese, K. I., Ahmed, F. R., Carey, P. R., Hasnain, S., Huber, C. P. and Storer, A. C. (1989). Crystal structure of a papain-E-64 complex. Biochemistry 28, 1330–1332. doi: 10.1021/bi00429a058.CrossRefGoogle ScholarPubMed
Veríssimo, C. J., Niciura, S. C. M., Alberti, A. L. L., Rodrigues, C. F. C., Barbosa, C. M. P., Chiebao, D. P., Cardoso, D., da Silva, G. S., Pereira, J. R., Margatho, L. F. F., da Costa, R. L. D., Nardon, R. F., Ueno, T. E. H., Curci, V. C. L. M. and Molento, M. B. (2012). Multidrug and multispecies resistance in sheep flocks from São Paulo state, Brazil. Veterinary Parasitology 187, 209–216. doi: 10.1016/j.vetpar.2012.01.013.CrossRefGoogle ScholarPubMed
Waller, P. J. (1997). Anthelmintic resistance. Veterinary Parasitology 72, 391–412. doi: 10.1016/s0304-4017(97)00107-6.CrossRefGoogle ScholarPubMed
Waller, P., Bernes, G., Thamsborg, S., Sukura, A., Richter, S., Ingebrigtsen, K. and Hoglund, J. (2001). Plants as de-worming agents of livestock in the Nordic countries: historical perspective, popular beliefs and prospects for the future. Acta Veterinaria Scandinavica 42, 31–44. doi: 10.1186/1751-0147-42-31.CrossRefGoogle ScholarPubMed
Waller, P. J., Dash, K. M., Barger, I. A., Le Jambre, L. F. and Plant, J. (1995). Anthelmintic resistance in nematode parasites of sheep: learning from the Australian experience. Veterinary Record 136, 411–413.CrossRefGoogle ScholarPubMed
Williams, P. L. and Dusenbery, D. B. (1990). Aquatic toxicity testing using the nematode, Caenorhabditis elegans . Environmental Toxicology and Chemistry 9, 1285–1290. doi: 10.1002/etc.5620091007.CrossRefGoogle Scholar
Wolstenholme, A. J., Fairweather, I., Prichard, R., von Samson-Himmelstjerna, G. and Sangster, N. C. (2004). Drug resistance in veterinary helminths. Trends in Parasitology 20, 469–476. doi: 10.1016/j.pt.2004.07.010.CrossRefGoogle ScholarPubMed
Woods, D. J. and Knauer, C. S. (2010). Discovery of veterinary antiparasitic agents in the 21st Century: a view from industry. International Journal for Parasitology 40, 1177–1181. doi: 10.1016/j.ijpara.2010.04.005.Google ScholarPubMed
Woods, D. J., Vaillancourt, V. A., Wendt, J. A. and Meeus, P. F. (2011). Discovery and development of veterinary antiparasitic drugs: past, present and future. Future Medicinal Chemistry 3, 887–896. doi: 10.4155/fmc.11.39.CrossRefGoogle ScholarPubMed
Yamamoto, R., Nagai, N., Kawabata, M., Leon, W. U., Ninomiya, R. and Koizumi, N. (2000). Effect of intestinal helminthiasis on nutritional status of schoolchildren. Southeast Asian J Trop Med Public Health 31, 755–761.Google ScholarPubMed
Zucker, S., Buttle, D. J., Nicklin, M. J. H. and Barrett, A. J. (1985). The proteolytic activities of chymopapain, papain, and papaya proteinase III. Biochimica et Biophysica Acta (BBA) – Protein Structure and Molecular Enzymology 828, 196–204. doi: 10.1016/0167-4838(85)90057-3.CrossRefGoogle ScholarPubMed