Existence of two geographically-linked clonal lineages in the bacterial fish pathogen Photobacterium damselae subsp piscicida evidenced by random amplified polymorphic DNA analysis

In this work, we applied the random amplified polymorphic DNA (RAPD) techni que to evaluate the genetic diversity in Photobacterium damselae subsp. pis cicida (formerly Pasteurella piscicida), an important pathogen for differen t marine fish. Regardless of the oligonucleotide primer employed, the 29 is olates of Ph. damselae subsp. piscicida tested were separated into two grou ps, the RAPD-PCR analysis differentiated the European strains from the Japa nese strains. The similarity between both groups estimated on the basis of the Dice coefficient was 75-80%. These results show that European and Japan ese isolates of Ph. damselae subsp. piscicida, regardless of their host fis h species, belong to two different clonal lineages. Our findings also indic ate that RAPD profiling constitutes a useful tool for epidemiological studi es of this fish pathogen.