Phylogenetic characterization and prevalence of Spirobacillus cienkowskii : a red-pigmented, spiral-shaped bacterial pathogen of the freshwater Cladoceran, Daphnia

Shrimp farming constitutes an important source of revenue and employment in many developing countries. However, infectious diseases have affected the profitability of the shrimp industry. For this reason, disease prevention is a priority and shrimp immunology has become a prime area of research. In such a perspective, studies into the value of cellular and humoral parameters as indicators of shrimp condition are being carried out, with the intention of developing criteria for sanitary surveys, immunomodulation studies and selection programs for shrimp with high resistance to pathogens. Several quantitative, fast and easy procedures are being adapted to evaluate the expression of the immune response of shrimp. In regard to cellular parameters, the hemogram and two cellular mechanisms, the radical oxygen intermediates (ROIs) generated during post- phagocytic events and phenoloxidase (PO) activity have been considered as potential markers. Concerning humoral parameters, the antibacterial activity of plasma and the concentration of plasma proteins can be considered as criteria of health status. Information is presented about the immunological tools used to evaluate these health markers and the results concerning the clinical significance of response modifications. (C) 2000 Elsevier Science B.V. All rights reserved.