First Detection of Francisella halioticida Infecting a Wild Population of Blue Mussels Mytilus edulis in the United Kingdom

• Published in: Pathogens (Basel) Vol. 11; no. 3; p. 329
• Main Authors: Cano, Irene, Parker, Abigail, Ward, Georgia M, Green, Matthew, Ross, Stuart, Bignell, John, Daumich, Caroline, Kerr, Rose, Feist, Stephen W, Batista, Frederico M
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 08-03-2022; MDPI
• Subjects: Bacteria; blue mussels Mytilus edulis; Conserved sequence; Digestive glands; DNA probes; Epithelial cells; Epithelium; Estuaries; Francisella halioticida; Gene sequencing; Genomes; Granulocytes; granulocytoma; Hybridization; Inclusion bodies; Infections; intracellular bacterium; Labeling; Leukocytes (granulocytic); Mollusks; Mortality; Mussels; Mytilus edulis; Nanopore sequencing; Nucleotides; Organisms; Pathogenicity; Pathogens; Phylogenetics; Population; Population decline; prokaryote cyst; rRNA 16S; United Kingdom > UK; France; Japan; Nanopore sequencing; blue mussels Mytilus edulis; prokaryote cyst; granulocytoma; intracellular bacterium; Francisella halioticida; 16S rRNA gene
• ISSN: 2076-0817; 2076-0817
• DOI: 10.3390/pathogens11030329

In the last decade, declines in the population of wild blue mussels
in the Tamar estuary (United Kingdom) have been noted. In archived samples collected from 2013 to 2019, between 7% (in 2013) and 18% (in 2019) showed large granulocytoma and haemocytic infiltration in the interstitial tissue of the digestive gland. Four samples were selected for
gene Nanopore sequencing. A consensus sequence of 1449 bp showed nucleotide similarities between 99.93-100% with published sequences of
. In situ hybridisation (ISH) confirmed the presence of
DNA within individual granulocytes of granulocytomas and also in prokaryotic-like inclusion bodies within the digestive epithelial cells. The design of diagnostic tests for surveillance of
including more specific ISH probes and sequencing the genome of the isolates infecting mussels, will shed more light on the pathogenicity and spread of this pathogen.