New data on aetiology of nodular gill disease in rainbow trout, Oncorhynchus mykiss

Abstract

Abstract:We studied amoebae associated with nodular gill disease (NGD) outbreaks in rainbow trout Oncorhynchus mykiss (Walbaum) in fish farms in South-Western Germany. Gills of 12 diseased rainbow trout were examined in fresh, by isolation attempts, histologically and using in situ hybridisation (ISH). A total of nine amoeba strains of the genera Acanthamoeba (1), Hartmannella (2), Naegleria (1), Protacanthamoeba (1) and Vannella (4) were isolated and determined using light microscopical, ultrastructural and molecular methods. Specific molecular probes designed from the SSU rDNA sequences of individual amoeba strains were used for non-radioactive ISH in histological sections. Association of Naegleria sp. with NGD and a direct ISH proof of Naegleria trophozoites attached to hyperplastic gill epithelium are novel findings, expanding the number of possible agents of NGD and supporting the hypothesis on multicausal aetiology of this disease.

Thermophilic potentially pathogenic amoebae isolated from natural water bodies in Poland and their molecular characterization

“…Our T16 sequences with GenBank accession numbers HQ632776, JQ408993 and JQ408994 showed 100% similarity to Acanthamoeba T16 GQ342606 sequence obtained from bronchoalveolar lavage (BAL) of Polish newborn with symptoms of atypical pneumonia (Lanocha et al 2009), in opposite to our remaining T16 sequences (JQ408995, JQ408996, HQ632775 and HQ632777) which similarity to GQ342606 was 99.68%. All our H. vermiformis strains were identical to each other and they showed the highest similarity (99%) to the sequences obtained earlier from different kinds of water bodies, isolated by us (HQ632781 -lake water, JQ409010 -fountain water, JQ409009 -fire water reservoir and JQ409008 -hospital tap water) and other au- (Dyková et al 2010). …”

Two new species of Ripella (Amoebozoa, Vannellida) and unusual intragenomic variability in the SSU rRNA gene of this genus

“…SUM1S/I, CAZ6/I, CAZ7/I, W181G/I, GERL14, GERL34, 805, DP13, GP2 and PS2, as well as an unnamed strain BEN3V originally designated Vannella sp. (Dyková and Kostka 2013;Dyková et al 2005Dyková et al , 2010) also belonged to this clade. The clade of Ripella spp.…”

“…This clade includes also previously sequenced R. platypodia and a number of unnamed strains previously studied and illustrated by Dyková et al (1996Dyková et al ( , 2005Dyková et al ( , 2010, and Dyková and Kostka (2013). SSU rRNA gene of the studied amoebae shared features characteristic of the genus Ripella, in particular, it is one of the shortest among Amoebozoa, with extensive deletions in the regions V2 and V4.…”

“…Unfortunately, too few members of this genus have been morphologically characterized until now. In spite of the presence of 5 unnamed isolates within a clade corresponding to Ripella (Dyková et al 1996(Dyková et al , 2005(Dyková et al , 2010Dyková and Kostka 2013), the genus has been remaining formally monotypic until now, and its diagnosis was mainly based on the characters of R. platypodia. Therefore, it contains very few differentiating morphological details, and outlines the group most reliably based on small-subunit ribosomal RNA gene sequence characteristics.…”

“…(Dyková et al 1996(Dyková et al , 2005(Dyková et al , 2010Dyková and Kostka 2013;Page 1968;Page and Blakey 1979;Smirnov et al 2007) shows that all currently known strains assigned to this genus are very similar to each other and to the type species R. platypodia in the set of light microscopic characters. Shapes and sizes of locomotive forms and structure of nucleus are nearly identical, while floating forms have only been illustrated for R. platypodia (Page 1968;Smirnov et al 2007) and two species investigated during the present study.…”