Evaluation of the intra and interspecific variability in the genus Perkinsus. Proteomic analysis of the parasite and its interaction with the host

Abstract

Clam culture industry is rising every year worldwide. The most produced species is the Manila clam Ruditapes philippinarum. China is the main producer country followed by Italy, South Korea, USA and Spain. The introduction of the Manila clam in Europe was between 1970 and 1980. R. philippinarum is well adapted and grows faster than native species R. decussatus, for this, is the most produced species in Europe. The production of venerids in Galicia is a very important socio-economic resource. The production of Manila clam in Galicia rose in the last years and now is the most produced species too. The infection by Perkinsus olseni is one of the most serious diseases affecting clams. The parasite is highly distributed worldwide and affect to a large list of molluscs. Mortality of R. decussatus and R. philippinarum was associated with P. olseni infection in south Europe as well as with R. philippinarum mortality in several Asian countries. Two species of the genus Perkinsus, P. olseni and P. marinus, are included in the list of notifiable diseases of the World Organization for Animal Health, which indicates the interest to stop the expansion of the disease. The knowledge of P. olseni is very scarce in comparison with P. marinus which provokes massive mortalities in oysters Crassostrea virginica in USA. The economic transcendence of the perkinsosis justifies the research for a better knowledge of the disease and minimizes their effects. With this purpose, this study was developed in order to know (1) the variability of P. olseni along the Spanish coast, with the emphasis in virulence variability among populations, and (2) the modulation of the Manila clam protein expression due to P. olseni infection, with emphasis in the search of protein markers of resistance to the disease. The study of the variability was done analyzing the genetic population structure as well as the proteome of P. olseni clons derived from several regions of the Spanish coast. Furthermore, the proteome of P. olseni was compared with the proteome of two species of the genus, P. marinus and P. chesapeaki, in order to amplify the perspective of the variability of P. olseni. The analysis of the modulation of the Manila clam protein expression due to P. olseni infection was focused in haemocytes and haemolymph. The effect of the exposition to P. olseni in clams was measured at short time and a long time with the aim in the modulation of the immune response of the clam to the parasite.