UTILIZACI?N DE MARCADORES MOLECULARES PARA EL DIAGN?STICO E IDENTIFICACI?N TAXON?MICA DE PROTOZOOS PAR?SITOS EN BIVALVOS

The development of molecular diagnosis based on the detection of specific DNA sequences has revolutionized the diagnosis of mollusc pathologies. Infectious diseases are especially relevant in bivalve mollusc farming primarily because these species are grown in the natural medium, sharing a habitat with natural populations. This situation diminishes the utility of applying traditional measures of eradicating parasite infestations. On the other hand the transport of live animals for commerce between different geographic zones has been the main factor in the propagation of parasites. Therefore, the establishment of programmes of vigilance and monitoring the presence of agents responsible for these diseases constitutes the proper control to avoid such propagation. The characterization of DNA molecular markers in the different pathogenic species permits the application of molecular biological techniques such as PCR and in situ hybridization in diagnosing parasites in bivalves. The high sensitivity, accurate specificity, and the greater speed in gaining results when a high number of samples are processed, with respect to histological techniques, enormously facilitate the application of these techniques as tools to identify pathogens present in bivalves. In the present work, after a general review, we present the methodology followed in the designing of a molecular diagnostic method for the detection of three protozoa responsible for many other parasite diseases: Perkinsus olseni, Marteilia refringens and Bonamia ostreae. We describe the method from isolation and characterization of sequences specific of the genome of each of these parasites, to the application of these molecular markers for the detection and taxonomic identification of the parasite species in the natural samples.