One Perkinsus species may hide another: characterization of Perkinsus species present in clam production areas of France

Abstract

Although clam populations in France are known to be infected with protozoans of the genus Perkinsus, no molecular characterization was previously performed on these parasites. Considering that several members of this genus have been associated with mortalities of molluscs worldwide, a study was undertaken in order to characterize these parasites in France. For that purpose, clams, Ruditapes philippinarum and R. decussatus, collected from different production areas and found to be infected with Perkinsus sp. in thioglycolate culture medium, were selected for PCR-RFLP tests and sequencing. Perkinsus olseni was detected in all the investigated areas and results also suggested the presence of P. chesapeaki in Leucate, a lagoon on the Mediterranean coast and in Bonne Anse in Charente Maritime, on the Atlantic coast. Clonal cultures from both detected species were produced in order to describe and compare in vitro stages. Differences in size between both Perkinsus spp. were noticed especially for schizonts and zoosporangia. Lastly, in situ hybridization tests allowed confirmation of the presence of both species in the same R. decussatus population and even in same clams. This is the first detection of P. chesapeaki in Ruditapes species and outside North America, which questions its introduction into Europe.

First report of Perkinsus honshuensis in the variegated carpet shell clam Ruditapes variegatus in Korea

“…Based on the results of a genus-specific Ray's fluid thioglycollate medium assay (RFTM; Ray 1966), histology, and DNA sequences of the ITS and NTS regions of the ribosomal rRNA gene complex, Park et al (2006) also reported the clam Protothaca jedoensis as a new host of P. olseni. These findings redundantly confirm P. olseni as a common or predominant agent of perkinsosis among clams in Korean waters (Park & Choi 2001, Ngo & Choi 2004 Arzul et al 2012). However, in light of the discovery of the new species P. honshuensis in Manila clams in nearby Japan (Dungan & Reece 2006, Takahashi et al 2009, Umeda & Yoshinaga 2012, it is important to clarify whether clam populations in Korean waters are indeed infected only by P. olseni.…”

Development and applications of Ray’s fluid thioglycollate media for detection and manipulation of Perkinsus spp. pathogens of marine molluscs

“…cells. Since cells of all confirmed Perkinsus species enlarge similarly in RFTM, differential estimates on abundances of individual Perkinsus species are not practical by this method for samples from several regions where multiple Perkinsus species are sympatric Reece et al, 2008;Arzul et al, 2012;da Silva et al, 2014). The same sources of analytical errors that are described for other RFTM assays may also confound results of RFTM assays of marine and estuarine water samples, and of excreta from infected host molluscs.…”

“…cells are also frequently used as inocula for proliferative Perkinsus sp. in vitro cultures (La Peyre and Faisal, 1995;Bushek and Allen, 1996;Burreson et al, 2005;Casas et al, 2005;Dungan and Reece, 2006;Arzul et al, 2012;da Silva et al, 2013). Several pragmatic advantages encourage the use of RFTM-enlarged Perkinsus sp.…”

“…Among those Perkinsus spp., several are sympatric in some locations, where they may also share common hosts Reece et al, 2008;Arzul et al, 2012;da Silva et al, 2014). Where biosecurity or research requirements demand differential identification of pathogen species, post hoc analyses may differentiate species-specific DNAs extracted from mollusc tissues that have been tested by RFTM assays.…”

Cell proteome variability of protistan mollusc parasite Perkinsus olseni among regions of the Spanish coast

“…It is likely that P. olseni was introduced into Europe by commercial trade of Manila clams R. philippinarum from Asian coasts (Hine 2001, Elandaloussi et al 2009a, Vilas et al 2011. It has spread through Italy (Da Ros and Canzonier 1985, Abollo et al 2006), Portugal (Azevedo 1989, Spain (Casas et al 2002a, Elandaloussi et al 2009b and France (Goggin 1992, Arzul et al 2012. Most studies on the genus Perkinsus have concentrated on P. marinus, which has been causing mass mortalities in Eastern oyster Crassostrea virginica populations of the Atlantic and Gulf coasts of the USA for more than 50 yr (Andrews 1996, Burreson & Ragone Calvo 1996, Ray 1996.…”