Susceptibility of common carp and sunfish to a strain of Francisella noatunensis subsp. orientalis in a challenge experiment

Abstract

Francisellosis, an emerging disease in many fish species, can cause high mortality in affected populations. Here we investigated the susceptibility of common carp Cyprinus carpio and sunfish Lepomis gibbosus to Francisella noatunensis subsp. orientalis (Fno), and possible transmission of the bacteria between the 2 fish species. In a challenge experiment, 3 groups of each species were injected intraperitoneally (IP) with 3 different doses of an Fno strain no. 9449 of the Norwegian Veterinary Institute, recovered from naturally infected ornamental Malawi cichlids. Infected carp were cohabitated with sunfish and vice versa. Control groups were injected with 0.9M phosphate-buffered saline and cohabitated accordingly. Fish were sampled at different time points. Mortality of challenged sunfish was observed during the first 96 h and reached 56.1%. In the control sunfish, 4 of 16 fish (25%) died within 48 h. In carp, no mortalities or clinical signs were observed during the experiment. General clinical and patho-anatomical disease signs of affected sunfish were observed. We detected granulomas in 2 cohabitated sunfish and 1 challenged carp, but could not re-isolate Fno from these fish. Fno was successfully cultured from 6 sunfish and 3 carp specimens until 35 d post injection. PCR of spleen and kidney with 16S rDNA Francisella-like bacterium primers 180f and 485r yielded amplicons in 68.3% of challenged sunfish and only 12.2% of challenged carp. We demonstrated that sunfish were susceptible to Fno infection while the carp were not. Horizontal transmission of the agent between the 2 fish species could not be demonstrated. KEY WORDS: Bacteria · Francisellosis · Cyprinus carpio · Lepomis gibbosus · TransmissionResale or republication not permitted without written consent of the publisher

Comparison of the pathogenicity of Francisella orientalis in Nile tilapia (Oreochromis niloticus), Asian seabass (Lates calcarifer) and largemouth bass (Micropterus salmoides) through experimental intraperitoneal infection

“…Melanomacrophage aggregates seen in high numbers inside granulomas in Asian seabass tissues (c, d). Scale bar = 50 μm [Colour figure can be viewed at wileyonlinelibrary.com] (Lewisch, Menanteau-Ledouble, Tichy, & El-Matbouli, 2016), and common carp and catfish did not die even when injected with a high dose (Dong et al, 2016). Different species of tilapia show different levels of susceptibility (Klinger-Bowen et al, 2016).…”

Diagnosis of piscine francisellosis in Largemouth Bass from a public display exhibit in north‐central Florida, USA

“…The route of F. orientalis introduction to the public display system remains uncertain. Previous challenge experiment results indicated that Pumpkinseed Lepomis gibbosus are susceptible to F. orientalis infection, so the possibility of transmission through frozen sunfish diets should be considered (Lewisch et al 2016). Alternatively, F. orientalis could have been introduced into the system through an infected wild-caught or aquaculture-raised fish.…”

Pathological and Tissue-Based Molecular Investigation of Granulomas in Cichlids Reared as Ornamental Fish

“…Moreover, the relevance of ornamental cichlids is not counterbalanced by literature references regarding pathologic conditions, with only a limited amount of papers being available [ 8 , 9 , 10 , 11 , 12 , 13 , 14 ].…”