RT Journal Article SR Electronic(1) A1 Pomaranski, Eric K. A1 Griffin, Matt J. A1 Camus, Alvin C. A1 Armwood, Abigail R. A1 Shelley, Johnny A1 Waldbieser, Geoffrey C. A1 LaFrentz, Benjamin R. A1 García, Julio C. A1 Yanong, Roy A1 Soto, EstebanYR 2020 T1 Description of Erysipelothrix piscisicarius sp. nov., an emergent fish pathogen, and assessment of virulence using a tiger barb (Puntigrus tetrazona) infection model JF International Journal of Systematic and Evolutionary Microbiology, VO 70 IS 2 SP 857 OP 867 DO https://doi.org/10.1099/ijsem.0.003838 PB Microbiology Society, SN 1466-5034, AB A recently described emergent disease of ornamental fish has been associated with an Erysipelothrix species positive for the surface protective antigen (spa) C gene. Whole genome sequencing was performed on five spaC Erysipelothrix isolates from diseased ornamental fish. In addition, these spaC Erysipelothrix isolates were compared to spaA-, spaB- and other spaC-positive Erysipelothrix species isolated from terrestrial and marine mammals, birds and fish using multi-locus sequence analysis (MLSA). The genomes of fish pathogenic spaC isolates were genetically distinct from Erysipelothrix rhusiopathiae , sharing 86.61–86.94 % average nucleotide identity (ANI) and digital DNA–DNA hybridization (dDDH) values of 31.6–32.2 %, but 99.01–99.11 % ANI and 90.8–91.9 % dDDH values with the uncharacterized spaC-positive Erysipelothrix sp. strain 2 isolated from swine. The findings indicate the spaC-positive fish and swine isolates are conspecific and represent a previously unrecognized taxon. While phylogenies inferred from MLSA sequences confirm this conclusion, slight genetic differences between the spaC fish isolates and swine strain 2 were indicated. Bath immersion challenge trials were conducted using tiger barbs (Puntigrus tetrazona) exposed by immersion to 107 c.f.u. ml−1 of three fish pathogenic spaC Erysipelothrix species, and three spaA and two spaB E. rhusiopathiae isolates as a model of infection. Thirty days post-challenge, cumulative mean percentage survival was 37 % for the spaA, 100 % for the spaB and 13 % for the spaC isolates, revealing differences in virulence among the various spa genotypes in fish. Genetic findings and observed differences in virulence demonstrate the fish pathogenic spaC isolates represent a novel species, for which the name Erysipelothrix piscisicarius sp. nov. is proposed. The type strain is E. piscisicarius 15TAL0474T (=NRRL B-65533T=ATCC-TSD-175T=DSM 110099T)., UL https://www.microbiologyresearch.org/content/journal/ijsem/10.1099/ijsem.0.003838