RESUMO
In any experimental approach many factors will have to be considered and each parasite will set its own technical limitations. Nevertheless the points mentioned in this article are likely to contribute to a full analysis of protozoa and helminth parasite antigens. Although the antigenic structure of most protozoa and helminth remains unknown, their life cycle may include several and sometimes many antigenic forms. The extent and significance of this antigenic liability must be recognized and fully characterized before we can understand parasite immunology. Several interconnecting lines of approach are possible and include examination of the following: a) in any given species the degree of variability occurring in a life cycle; b) the extent to which total antigenic structure is involved in any changes that occur; c) the comparative protective value of these antigens; d) the effect of vector transmission on the antigenic repertoire of the parasite; e) the comparison of strains in relation to their geographical distribution; f) antigen immunochemistry and its relationship to parasite physiology; and g) the character of the immune response stimulated by each stage of the parasite
The experimental approach to these problems involves four fundamental points: 1) Parasites must be maintained under constant conditions, with strain histories recorded in full. Where strains are maintained in vivo ...(AU)
