Irodalmi áttekintés a süllő és sügér esetében előforduló vírusos és baktériumok okozta betegségekről

A fogassüllő (Sander lucioperca L.) intenzív tenyésztésére több próbálkozás történt már Magyarországon, melyekről számos közlemény, szakmai előadás (Horváth és mtsai, 2005, Tamás és mtsai, 2006, Bódis és mtsai, 2005; Szabó és mtsai, 2007), valamint PhD disszertáció (Molnár, 2002, Bódis, 2008, Szabó, 2009, Németh, 2013) is született. Az eredményes tenyésztés korlátozó tényezői lehetnek a nevelés során fellépő betegségek, melyek felismerése, megelőzése és az ellenük való védekezés kidolgozása elengedhetetlen fontosságú. Témacsoportunk munkatársai a Halászat 109/2 számában megjelent cikkben (Molnár és mtsai, 2016) már beszámoltak a balatoni fogassüllőt károsító parazitás fertőzöttségekről, kiemelve az intenzív rendszerekben is potenciális veszélyt jelentő patogén kórokozókat. Hazánkban egy korábbi előadásanyagban Csaba és mtsai. (2008) ismertették a ragadozóhalakat, köztük a süllőt is érintő, abban az időben ismert betegségeket. A vírusok és baktériumok okozta, süllőt érintő betegségekről ugyanakkor hazánkban csekély tapasztalattal rendelkezünk, bár jelentőségük korán sem elhanyagolható. Így, jelen tanulmányunkban az európai és észak-amerikai (intenzív süllő és sügér) telepeken jelentkező megbetegedésekben kimutatott kórokozókról szerzett információkat gyűjtöttük össze és ismertetjük

Molecular detection and genome analysis of circoviruses of European eel (Anguilla anguilla) from Lake Balaton

Circoviruses are small, non-enveloped viruses with a circular single-stranded (ss) DNA genome, which ranges from about 1.3-2.3 kb in size. The genome contains at least two open reading frames (ORF) arranged on different strands, these encode the replication (Rep) and capsid (Cap) proteins. Before the last decade, circoviruses were known only from birds and swine, but recently, due to the different metagenomic methods and PCR based diagnostic tests, numerous circovirus-related sequences were described from environmental samples, invertebrates and also from lower vertebrates (amphibian and fish). According to the increasing number of the detected piscine circoviruses, a monitoring program (Bioclimate) is carried out for screening circoviruses in Hungarian freshwater fishes. Samples were taken regularly also from Lake Balaton. In March 2014, fifteen living European eels (Anguilla anguilla) and two razorfish (Pelecus cultratus) were caught among other species at the Sió-floodgate sampling site. After euthanasia, tissue samples were collected from the gills, liver, spleen, kidney and intestine. The presence of circoviral DNA was detected by a broad-spectrum nested PCR, targeting the Rep gene. In case of positive results, rolling circle amplification and inverse nested PCR reactions were carried out to amplify the remaining part of the circular genomes. Six out of the fifteen eels, and one razorfish sample were found to be positive for circoviral DNA. Analysis of these fragments revealed the presence of three different circovirus-related rep-like sequences. One of them (representing with 3 samples) was identical with the previously described eel circovirus (EeCV) by Doszpoly et al. (2014). The whole genome amplification of these 3 samples was also successful. Comparing the partial rep-like sequences, two other samples were similar with 96% nucleotide identity to the above mentioned ones, and were identical to the rep-like sequence originating from razorfish. The 6th circovirus positive sample showed only 50% similarity to the EeCV, but it was found to be identical to the rep-like sequences of roaches (Rutilus rutilus) caught from Lake Balaton, recently. Circoviruses were described as host-specific or narrow host range microorganisms. To the best of our knowledge, this is the first report about the detection of the same circovirus related sequences in various, distantly related fishes and the occurrence of different rep-like sequences in the same fish species

Molecular detection and genome analysis of circoviruses of European eel (Anguilla anguilla) and Sichel (Pelecus cultratus) from lake Balaton, Hungary

Balatoni angolnákból és gardából kimutatott cirkovírusok genomiális szintű összehasonlító vizsgálat

Description of Henneguya jaczoi sp. n. (myxosporea, myxobolidae) from Perca fluviatilis (L.) (pisces, percidae) with some remarks on the systematics of Henneguya spp. of european fishes

A new Henneguya species, H. jaczoi sp. n., is described from perch (Perca fluviatilis) from Lake Balaton, Hungary. This species infects the palatal region of the fish, forming large plasmodia in the thickened caudal part of the buccal cavity and at the dorsal ends of the cartilaginous gill arches. The species differs from the gill-dwelling Henneguya species of perch and pike (Esox lucius) both morphologically and in molecular aspects. The authors conclude that the type species H. psorospermica Thélohan is a specific parasite of pike, while the species forming plasmodia in the gills of perch corresponds to H. texta Cohn, which was hitherto regarded as a synonym of H. psorospermica. Besides the above-mentioned species, H. creplini was frequently found in pikeperch (Sander lucioperca) and Volga pikeperch (Sander volgensis), but no Henneguya infection has been recorded in ruffe (Gymnocephalus cernua), which is a common percid fish of the lake and is known to be the type host species for H. creplini

Myxobolus infection in the cornea of the roach (Rutilus rutilus) in Lake Balaton

Infection of the cornea in fishes by Myxobolus plasmodia is a common but still little known site preference of myxosporeans. A sporadic but striking infection in the cornea of the roach (Rutilus rutilus) was observed in Lake Balaton, Hungary. Relatively small, round plasmodia 250 to 500 μm in diameter developed in the dense connective tissue of the cornea. Morphological and molecular biological examination of spores collected from cysts in the cornea demonstrated that this infection is caused by Myxobolus fundamentalis, a species hitherto reported only from the cartilaginous gill arch of the roach. The 18S rDNA sequences of spores from the cornea showed 99.9% identity to the sequences of spores from the gill arch, and they also shared 99.9% identity with the sequences of triactinomyxon actinospores obtained from the oligochaete Isochaetides michaelseni

Molecular detection and genome analysis of circoviruses of European eel (Anguilla anguilla) and sichel (Pelecus cultratus)

The prevalence and distribution of piscine circoviruses (CVs) were tested in a routine virus monitoring programme in Lake Balaton, Hungary. A high prevalence of European eel CV (EeCV) was found in the apparently healthy eel population (35.5%). The copy number of the viral DNA in different organs was determined by quantitative real-time PCR. The results suggested that some eel specimens were in active viraemic status despite their asymptomatic condition. Furthermore, a novel, previously undescribed CV was also detected in eel and sichel samples. Full genome characterisation confirmed that the virus represents a novel EeCV species (EeCV-2). The genome contains an integrated eel chromosome-derived fragment, suggesting that the original host of the virus was the eel and it probably emerged subsequently in the sichel by host switching. In some samples, an additional, 1,111-nt-long circular ssDNA was also observed involving a CV-like stem-loop structure and an ORF showing homology to CV capsid protein genes, without any sign of a replication initiator protein sequence

Three new species of Myxobolus Bütschli, 1882 (Myxozoa: Myxobolidae) infecting the common nase Chondrostoma nasus (L.) in the River Danube

The common nase Chondrostoma nasus (L.) is a frequent cyprinid fish in the River Danube. In a survey on its infection with myxosporeans, eight different Myxobolus spp. spore types were found in the gills, swim bladder, fins and intestinal wall. Of these, spore types representing three species were studied in detail by morphological and molecular methods. Based on the differences in 18S rDNA sequences, two new species of Myxobolus Bütschli, 1882 from the gills and one from the swim bladder are described: M. arrabonensis n. sp., M. szentendrensis n. sp. and M. paksensis n. sp. The new species resembled M. muelleri Bütschli, 1882, M. intimus Zaika, 1965 and M.cycloides Gurley, 1893, all parasitic in leuciscine cyprinids, in spore size and location in the host, but exhibited differences in partial 18S rDNA sequences as follows: M. arrabonensis - M. muelleri (1.4%), M. szentendrensis - M. intimus (2.8%), M. paksensis - M. cycloides (2.4%). Based on the significant differences in rDNA sequences, the three forms are considered to represent new, hitherto undescribed species in spite of their morphological similarities to some Myxobolus spp. forming spores in identical locations in genetically closely related cyprinids of the subfamily Leuciscinae

Balatoni angolnákból (Anguilla anguilla) és gardából (Pelecus cultratus) kimutatott circovírusok molekuláris elemzése

Balatoni angolnákban és gardában kimutatott cirkovírusok részleges és teljes genom alapú összehasonlító vizsgálat

Detection of cyprinid herpesvirus 1 (CyHV-1) in barbel (Barbus barbus): First molecular evidence for the presence of CyHV-1 in fish other than carp (Cyprinus carpio)

Two adult barbels (Barbus barbus) with visible skin tumours were subjected to histopathological and molecular examinations. The fish were caught in the River Danube near Budapest. Papillomas were found around their oral cavity, at the operculum and at the pectoral fins, while epidermal hyperplasias were seen on the body surface. Cyprinid herpesvirus 1 (CyHV-1) was detected in the kidney of the specimens by polymerase chain reaction (PCR), and barbel circovirus 1 (BaCV1) was found in all internal organs and in the tissues of the tumours. The whole genome of BaCV1 and three conserved genes from the genome of CyHV-1 were sequenced. Previously, BaCV1 had been reported only once from a mass mortality event among barbel fry. The whole genome sequence of our circovirus shared 99.9% nucleotide identity with that of the formerly reported BaCV1. CyHV-1 is known to infect common carp and coloured carp (Cyprinus carpio), and has been assumed to infect other cyprinid fish species as well. We found the nucleotide sequences of the genes of CyHV-1 to be identical in 98.7% to those of the previous isolates from carp. To the best of our knowledge, this is the first molecular confirmation of the presence of CyHV-1 DNA in cyprinid fish species other than carp