Immunological Parasites

The science of immunology not only encompasses the body s immune responses to bacteria and viruses but is extensively involved in tumour recognition and subsequent rejection the rejection of transplanted organs and tissues the elimination of parasites ftom the body allergies and autoimmunity (the condition when the body mounts a reachon agairrst its own tissues). 

Boreham, P.F.L. and Atwell, R.B. (1983) Adverse drug reactions in the treatment of filarial parasites haematological, biochemical, immunological and pharmacological changes in Dirofilaria immitis infected dogs treated with diethylcarbamazine. International Journal for Parasitology 13, 547-556. 

Taken as a whole, these observations show that parasite lines differ in an immune-dependent manner in their infection/expulsion kinetics. Furthermore, there is heritable variation in survival and fecundity in previously exposed hosts and quantitative variation in the immune response that selected parasite lines elicit. Again, taken as a whole, these observations have the necessary corollary that variation in these traits exists not only in laboratory-maintained isolates but also in helminth species in nature. The phenotypes under consideration here (infection/expulsion kinetics, survival, fecundity) are multifactorial life-history traits. Understanding the basis of variation in the components and interplay of these complex, immune-responsive phenotypes must be of crucial relevance to understanding the immunology of infections of parasitic nematodes. This is of particular relevance in view of current attempts to develop immunological methods of nematode control. 

Other contributions to this book have taken a molecular view of parasitic nematodes, yet molecules make only a rather brief appearance here. This chapter has tried to show that parasitic nematodes are fascinatingly and tantalizingly diverse at a phenotypic level. It has focused particularly on diversity in phenotypes that are apparent in response to environmental conditions within or outside a host. The interaction of parasites with within-host factors is a major current research effort. However, helminth immunology is particularly notable for its inattention to diversity, especially when compared with the immunology of parasitic protozoa (Read and Viney, 1996). Observations of the interaction of host immunity with subsequent development in S. ratti show the potential power of such interactions. It is also clear that a principal mechanism of the action of host immune responses is against nematode fecundity (Stear et al., 1997). This is likely to be a molecularly complex interaction. Understanding this interaction, as well as variation in the interaction is interesting, but could also form the basis of control by transmission-reduction rather than eradication per se. 

Behnke, J.M., Hannah, J. and Pritchard, D.I. (1983) Nematospiroides dubius vci the mouse evidence that adult worms depress the expression of homologous immunity. Parasite Immunology 5, 397-408. 

Fraser, E.M. and Kennedy, M.W. (1990) Heterogeneity in the expression of surface exposed epitopes among larvae of Ascaris lumbricoides. Parasite Immunology 13, 219-225. 

Maizels, R.M., Bundy, D.P., Selkirk, M.E., Smith, D.F. and Anderson, R.M. (1993) Immunological modulation and evasion by helminth parasites in human populations. Nature 365, 797-805. 

Vos, J.G., Ruitenberg, E.J., Van Basten, N., Buys, J., Elgersma, A. and Kruizinga, W. (1983) The athymic nude rat. IV. Immunocytochemical study to detect T-cells, and immunological and histopathological reactions against Trichinella spiralis. Parasite Immunology 5, 195—215. 

This was the original hypothesis put forward by Lee (1970) and expanded by Ogilvie et al. (1973). Secretory products of N. brasiliensis do indeed decrease the amplitude of contractions of segments of uninfected rat intestine maintained in an organ bath, but a role for AChE in this phenomenon was discounted due to the heat stability of the parasite factor, and the inability to duplicate the effect with AChE from the electric eel (Foster et al., 1994). Subsequent investigations demonstrated that the suppression of contraction could be duplicated by a 30-50 kDa fraction of secreted products, which contained a protein of 30 kDa that was immunologically cross-reactive with mammalian vasoactive intestinal peptide (VIP). Moreover, an antibody to porcine VIP significantly reduced the inhibitory effect of parasite-secreted products on contraction in vitro (Foster and Lee, 1996). 

Blackburn, C.C. and Selkirk, M.E. (1992b) Inactivation of platelet activating factor by a putative acetylhydrolase from the gastrointestinal nematode parasite Nippostrongylus brasiliensis. Immunology 75, 41 -A 6. 

Kennedy, M.K., Maizels, R.M., Meghji, M., Young, L., Qureshi, F. and Smith, H.V. (1987) Species-specific and common epitopes on the secreted and surface antigens of Toxocara cati and Toxocara canis infective larvae. Parasite Immunology 9, 407-420. 

Maizels, R.M., de Savigny, D. and Ogilvie, B.M. (1984) Characterization of surface and excretory-secretory antigens of Toxocara canis infective larvae. Parasite Immunology 6, 23-37. 

Karanu, F.N., McGuire, T.C., Davis, W.C., Besser, T.E. and Jasmer, D.P. (1997a) CD4+T lymphocytes contribute to protective immunity induced in sheep and goats by Haemonchus contortus gut antigens. Parasite Immunology 19, 435—145. 

Knox, D.P., Smith, S.K. and Smith, W.D. (1999) Immunization with an affinity purified protein extract from the adult parasite protects lambs against Haemonchus contortus. Parasite Immunology 21, 201-210. 

Munn, E.A., Smith, T.S., Smith, EL, Smith, F. and Andrews, S.J. (1997) Vaccination against Haemonchus contortus with denatured forms of the protective antigen Hll. Parasite Immunology 19, 243—248. 

Britton, C., Canto, G.J., Urquhart, G.M. and Kennedy, M. (1993) Characterization of excretory-secretory products of adult Dictyocaulus viviparus and the antibody-response to them in infection and vaccination. Parasite Immunology 15,163-174. 

Kennedy, M.W., Qureshi, F., Fraser, E.M., Haswell-Elkins, M.R., Elkins, D.B. and Smith, H.V. (1989) Antigenic relationships between the surface-exposed, secreted and somatic materials of the nematode parasites Ascaris lumbricoides, Ascaris suum and Toxocara canis. Clinical and Experimental Immunology 75, 493-500. 

Maizels, R.M., Burke, L. and Denham, D.A. (1987c) Phosphorylcholine-bearing antigens in filarial nematode parasites analysis of somatic extracts, in-vitro secretions and infection sera from Brugia malayi and B. pahangi. Parasite Immunology 9, 49-66. 

Ortega-Pierres, M.G., Yepez-Mulia, E., Homan, W., Gamble, H.R., Lim, P.L., Takahashi, Y., Wassom, D.L. and Appleton, J.A. (1996) Workshop on the detailed characterisation of Trichinella spiralis antigens a platform for the future studies on antigens and antibodies to this parasite. Parasite Immunology 18, 273-284. 

Raleigh, J.M., Brandon, M.R. and Meeusen, E. (1996) Stage-specific expression of surface molecules by the larval stages of Haemonchus contortus. Parasite Immunology 18,125-132. 

Kennedy, M.W. and Qureshi, F. (1986) Stage-specific secreted antigens of the parasitic larval stages of the nematode Ascaris. Immunology 58, 515-522. 

Betts, C.J. and Else, K.J. (1999) Mast cells, eosinophils, and antibody-mediated-cellular-cytotoxicity are not critical in resistance to Trichuris muris. Parasite Immunology 21, 45-52. 

Castro, G.A., Hessel, J.J. and Whalen, G. (1979) Altered intestinal fluid movement in response to Trichinella spiralis in immunized rats. Parasite Immunology 1, 259-266. 

Dehlawi, M.S., Wakelin, D. and Behnke, J.M. (1987) Suppression of mucosal mastocytosis by infection with the intestinal nematode Nematospiroides dubius. Parasite Immunology 12, 561-566. 

Else, KJ. and Wakelin, D. (1989) Genetic variation in the humoral immune response of mice to the nematode Trichuris muris. Parasite Immunology 11, 77-90. 

Else, K.J., Wakelin, D., Wassom, D.L. and Hauda, KM. (1990b) MHC-restricted antibody responses to Trichuris muris excretory/secretory (E/S) antigen. Parasite Immunology 12, 509-527. 

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