In vitro efficacy of new antiprotozoals against Philasterides dicentrarchi (Ciliophora, Scuticociliatida)

Abstract

Philasterides dicentrarchi is a histiophagous ciliate that causes severe losses in turbot and sea bass farming. This study investigated the in vitro efficacy against P. dicentrarchi of 85 newly synthesized compounds and 12 commercial compounds, of which 2 are fluoroquinolones (norfloxacine and lomefloxacine) with known antibacterial activity. Seventeen of the newly synthesized compounds (2 naphthyridines, 2 pyridothienodiazines and 13 pyridothienotriazines) and the fluoroquinolone norfloxacin showed good activity. The most promising compound was the pyridothienotriazine 12k, with activity similar to that of the salicylanilides niclosamide and oxiclozanide (MLC 0.8 mg l -1 in PBS, 1.5 mg l -1 in seawater; MLC = minimum 24 h lethal concentration).KEY WORDS: Philasterides dicentrarchi · Turbot · Scuticociliatosis · In vitro assay · Naphthyridines · Pyridothienotriazines · PyridothienodiazinesResale or republication not permitted without written consent of the publisher

Immune response of turbot, Psetta maxima (L.) (Pisces: Teleostei), to formalin-killed scuticociliates (Ciliophora) and adjuvanted formulations

“…Thus far, despite the toxicity of several common chemicals tested in vitro on the ciliates [10,11], the in vivo application of common treatments in the farms has been unsuccessful, most likely due to the internal location of the parasites. In this scenario, preventive measures based on immunoprophylaxis are an attractive option, considering the empirical data from field observations in affected farms pointing to the acquisition of disease resistance in fish surviving scuticociliate epizootics.…”

Identification of scuticociliate Philasterides dicentrarchi from indo-pacific seahorses Hippocampus kuda

“…The causative agents of scuticociliatosis in Korea have been isolated and identified as Uronema marinum (Jee et al, 2001), Pseudocohnilembus persalinus (Kim et al, 2004b), Philasterides dicentrarchi (Kim et al, 2004a). P. dicentrachi and Miamiensis avidus have caused mass mortality in turbot farms in Spain, Portugal, and France (Dyková and Figueras, 1994;Iglesias et al, 2001;Álvarez-Pellitero et al, 2004;Paramá et al, 2004). Seahorses are especially popular in some Asian countries due to strong demand from the Chinese traditional medicine and the souvenir trade on a global scale (Marichamy et al, 1993;Vincent, 1995).…”

Scuticociliatosis and its recent prophylactic measures in aquaculture with special reference to South Korea

“…Iglesias et al [14] proposed blood as one possible dissemination route within fish tissues and Paramá et al [44] demonstrated its chemoattractant properties for scuticociliates. The tendency to anaemia is consistent with the haematophagous activity of scuticociliates [10,14,19].…”

“…P. dicentrarchi causes fatal systemic scuticociliatosis in several cultured marine fish including sea bass [8], olive flounder [15], turbot [10,14,18], and gilthead bass [8] and turbot [9,16,20]. So far in NW Spain (Galicia) only P. dicentrarchi has been reported to cause mass mortality in turbot farms [7], although some authors have reported disease outbreaks caused by species of Philasterides and Miamiensis in turbot farms in Spain, Portugal, and France [10,14,18,44]. I. multifiliis and C. irritans are obligate parasites that cause significant economic loss in aquaculture [2].…”