Parasitic helminth

Blaxter, M.L., Aslett, M., Daub, J., Guiliano, D. and The Filarial Genome Project (1999) Parasitic helminth genomics. Parasitology 118, S39-S51. 

Gasser, R.B., Chilton, N.B., Hoste, H. and Beveridge, I. (1993) Rapid sequencing of rDNA from simile worms and eegs of parasitic helminths. Nucleic Acids Research 21, 2525-2526. 

Rocha, J. and Munn, E.A. (1997) P150, a protective glycoprotein complex of the microvillar membrane of Haemonchus contortus. Conference Abstract from Parasitic Helminths - from Genomes to Vaccines, Edinburgh, UK, 6-9 September 1997. 

Tort, J., Brindley, P.J., Knox, D.P., Wolfe, KH. and Dalton,J.P. (1999) Proteases and associated genes of parasitic helminths. Advances in Parasitology 43, 162-166. 

LBPs are likely to have conventional roles in the energy metabolism and transport of lipids in nematodes for membrane construction, etc. Many parasitic helminths have deficiencies in the synthesis of some lipids and so their lipid acquisition, transport and storage mechanisms clearly need to be specialized and therefore pertinent to the host-parasite relationship (Barrett, 1981). From a practical point of view, lipid transporter proteins may also be important in the delivery of anthelmintic drugs to their target most anthelmintics are hydrophobic and if they do not distribute to their site of action within the parasites by simple diffusion across and along membranes, then the parasite s own carrier proteins may be involved. 

Barrett, J. (1981) Biochemistry of Parasitic Helminths. MacMillan, London. 

Pritchard, D.I., Hewitt, C. and Moqbel, R. (1997) The relationship between immunological responsiveness controlled by T helper 2 lymphocytes and infections with parasitic helminths. Parasitology S33-S44. 

Parasitic helminths, such as Ascaris lumbricoides, Trichuris trichiura, hookworms, schistosomes and filarial nematodes are highly prevalent in tropical and subtropical areas of the world [1]. These infections often overlap and affect more than 1 billion... 

Pearce EJ, Caspar P, Grzych J-M, Lewis FA, Sher A Downregulation of Thl cytokine production accompanies induction of Th2 responses by a parasitic helminth, Schistosoma mansoni. J Exp Med 1991 173 159-166. 

Boyle, J.P., and Yoshino, T.P. (2003) Gene manipulation in parasitic helminths. International Journal for Parasitology 33, 1 259-1 268. 

Davies, R.E., Parra, A., LoVerde, P.T., Ribeiro, E., Glorioso, G. and Hodgson, S. (1 999) Transient expression of DNA and RNA in parasitic helminths by using particle bombardment. Proceedings of the National Academy of Sciences USA 96, 8687-8692. 

Neumann, S., Ziv, E., Lantner, F. and Schechter, I. (1 993) Regulation of Hsp70 gene expression during the life cycle of the parasitic helminth Schistosoma mansoni. European Journal of Biochemistry 21 2, 589-596. 

In contrast to parasitic helminths, very few proteases of the snail hosts have been characterized at the functional and molecular levels (Sajid and McKerrow, 2002). Proteolytic enzymes have been implicated in playing a role in parasite destruction or survival in the snail host. Elevation of lysosomal enzyme activity in... 

The remarkable success that has been achieved with identification of protective, recombinant antigens against the Taenia and Echinococcus species has been in stark contrast to the general lack of success that has been achieved with vaccine development against other parasitic helminth infections (Dalton and Mulcahy, 2001). Hence, very little direction has been available from the experiences of others on how to translate a laboratory success with an anti-parasite vaccine into a practical (commercial) vaccine. First principles would suggest a host of issues that require investigation/opti-mization, for example ... 

In the oxidative branch of malate dismutation, malic enzyme oxidizes malate to pyruvate, which is then further oxidized to acetyl-CoA by pyruvate dehydrogenase, an enzyme complex specially adapted to anaerobic functioning in Ascaris suum and possibly in other parasitic helminths like the trematode F. hepatica and the cestode Dipylidium caninum (Diaz and Komuniecki, 1994 Klingbeil et al., 1996). Parasitic helminths like F. hepatica use an acetate succinate CoA-transferase (ASCT) for... 

In accordance with their opportunistic way of life, parasitic flatworms have limited biosynthetic capacities as described in Introduction, they obtain many simple substrates from their hosts. More complex molecules that the parasite cannot obtain directly from the host are synthesized from these simpler building blocks. Obviously, the parasite has to synthesize complex structures like proteins and DNA. In general, the biosynthetic pathways of parasitic helminths bear a close resemblance to those of their mammalian hosts. However, the enzymes of these pathways often possess different properties, and in cases where parasites produce unique end products, there may be distinct pathway components that involve unique enzymes that are absent from the host. 

Purine and pyrimidine nucleotides are essential components of many biochemical molecules, from DNA and RNA to ATP and NAD. In recent years, the pyrimidine and especially the purine metabolism of parasitic helminths have been investigated extensively, mainly because they are different from the pathways in the mammalian host such that they have potential as targets for chemotherapeutic attack. For a review of purine and pyrimidine pathways in parasitic helminths and protozoa, see Berens et al. (1995). Although parasitic helminths do not synthesize purines de novo, but obtain them from the host, they do possess elaborate purine salvage pathways for a more economical management of this resource. Pyrimidines, on the other hand, are synthesized de novo by all parasitic flat-worms studied so far and, as with mammalian... 

Polyamines like spermidine and spermine, which bind tightly to nucleic acids and are abundant in rapidly proliferating cells, are present in parasitic helminths in amounts comparable to those in vertebrate cells. As the enzymes necessary for their synthesis are lacking in adult parasitic flatworms, it is assumed that these compounds are obtained from the host (Bacchi and Yarlett, 1 995). In F. hepatica a polyamine N-acetyltransferase has been characterized, that is thought to play a major role in the polyamine metabolism of this parasite by inactivating excess amines (Aisien and Walter, 1993). 

Helens, A.C.M. (1 994) Energy generation in parasitic helminths. Parasitology Today 1 0, 346-352. 

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