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Multilocus sequence typing reveals clonality in Saprolegnia parasitica outbreaks
Author(s) -
Ravasi Damiana,
De Respinis Sophie,
Wahli Thomas
Publication year - 2018
Publication title -
journal of fish diseases
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.819
H-Index - 85
eISSN - 1365-2761
pISSN - 0140-7775
DOI - 10.1111/jfd.12869
Subject(s) - biology , outbreak , genotype , population , ecology , molecular epidemiology , host (biology) , zoology , veterinary medicine , demography , genetics , gene , virology , sociology , medicine
The molecular epidemiology of fish pathogen Saprolegnia parasitica is still largely unknown. We developed a multilocus sequence typing scheme based on seven housekeeping genes to characterize 77 S. parasitica strains isolated from different fish host species at different times and from different geographic areas in Switzerland between 2015 and 2017. Ten different diploid sequence types ( DST s) were identified. The majority (52%) of outbreaks in Switzerland seemed to be caused by one genotype, namely DST 3, which was recovered from farm‐raised and wild‐caught fish in all the geographic areas and river basins included in the study. DST 3 was also recovered from the rivers Bienne (eastern France) and Doubs, where the episodes of massive mortality due to saprolegniosis started in 2009. Another genotype ( DST 7) showed, to a lesser extent, a distribution across different river basins, while eight DST s were unique to a defined geographic area or river basin. The occurrence of sporadic DST s indicates a certain degree of diversity within S. parasitica in the environment. The wide distribution of DST 3 suggests that a clonal population may have spread in eastern France and Switzerland across geographic barriers, with strong implications for the management of both captive and wild fish populations.