Koi-Herpesvirus Übertragung vom Laichkarpfen zur Brut?: Untersuchungen zur Risikobewertung der Übertragung des Koi-Herpesvirus durch Laichkarpfenbestände zur Sicherung nachhaltiger Sanierungserfolge der KHV-I in Sachsen und im Hinblick auf die Erhaltung der genetischen Vielfalt der Laichfischbestände in Sachsen

Im Bericht wird bisher ungeklärten Fragen des Übertragungswegs des Koi-Herpesvirus nachgegangen. In latent infizierten Laichkarpfenbeständen, in deren Geschlechtsprodukten und in befruchteten Eiern lässt sich das Virus (KHV) nachweisen. Eine Infektion der frisch geschlüpften Karpfenbrut scheint allerdings nicht zu erfolgen. Brütlinge von Laichfischen, die aus KHV-positiven Beständen stammen, haben eine höhere Resistenz gegenüber einer erneuten Infektion mit dem KHV. Der Beitrag richtet sich an praktische Fischzüchter, Fachtierärzte, Fischereiwissenschaftler und an die interessierte Öffentlichkeit. Redaktionsschluss: 31.03.202

Characterization of carp seminal plasma Wap65-2 and its participation in the testicular immune response and temperature acclimation

International audienceTwo functionally distinct isoforms of warm-temperature acclimation related 65-kDa protein (Wap65-1 and Wap65-2) with a role in the immune response are present in fish. To our knowledge, contrary to Wap65-1, Wap65-2 has neither been isolated nor functionally characterized in carp especially in reproductive system. The aim of this study was to characterize Wap65-2 and ascertain its functions in immune response and temperature acclimation within reproductive system. Wap65-2 corresponded to one of the most abundant proteins in carp seminal plasma, with a high immunologic similarity to their counterparts in seminal plasma of other fish species and a wide tissue distribution, with predominant expression in the liver. The immunohistochemical localization of Wap65-2 to spermatogonia, Leydig cells, and the epithelium of blood vessels within the testis suggests its role in iron metabolism during spermatogenesis and maintenance of blood-testis barrier integrity. Wap65-2 secretion by the epithelial cells of the spermatic duct and its presence around spermatozoa suggests its involvement in the protection of spermatozoa against damage caused by heme released from erythrocytes following hemorrhage and inflammation. Our results revealed an isoform-specific response of Wap65 to temperature acclimation and Aeromonas salmonicida infection which alters blood-testis barrier integrity. Wap65-2 seems to be related to the immune response against bacteria, while Wap65-1 seems to be involved in temperature acclimation. This study expands the understanding of the mechanism of carp testicular immunity against bacterial challenge and temperature changes, in which Wap65-2 seems to be involved and highlights their potential usefulness as biomarkers of inflammation and temperature acclimation

Experimental infections of different carp strains with the carp edema virus (CEV) give insights into the infection biology of the virus and indicate possible solutions to problems caused by koi sleepy disease (KSD) in carp aquaculture

Outbreaks of koi sleepy disease (KSD) caused by carp edema virus (CEV) may seriously affect populations of farmed common carp, one of the most important fish species for global food production. The present study shows further evidence for the involvement of CEV in outbreaks of KSD among carp and koi populations: in a series of infection experiments, CEV from two different genogroups could be transmitted to several strains of naïve common carp via cohabitation with fish infected with CEV. In recipient fish, clinical signs of KSD were induced. The virus load and viral gene expression results confirm gills as the target organ for CEV replication. Gill explants also allowed for a limited virus replication in vitro. The in vivo infection experiments revealed differences in the virulence of the two CEV genogroups which were associated with infections in koi or in common carp, with higher virulence towards the same fish variety as the donor fish. When the susceptibility of different carp strains to a CEV infection and the development of KSD were experimentally investigated, Amur wild carp showed to be relatively more resistant to the infection and did not develop clinical signs for KSD. However, the resistance could not be related to a higher magnitude of type I IFN responses of affected tissues. Despite not having a mechanistic explanation for the resistance of Amur wild carp to KSD, we recommend using this carp strain in breeding programs to limit potential losses caused by CEV in aquaculture

Proteomic analysis of carp seminal plasma provides insights into the immune response to bacterial infection of the male reproductive system

Aeromonas salmonicida is recognized as a significant bacterial pathogen in ulcerative disease of cyprinid fish. However, the mechanism of immunity to these bacteria in common carp is still not well understood, especially the immune regulation in the gonad to bacterial infection. The aims of our study were to analyze changes in the seminal plasma proteome following A. salmonicida infection in carp males. The observed pathological changes in the tissue (liver, spleen, kidney and testis) morphology and upregulation of immune-related genes (tnfa2, il6a) confirmed the successful infection challenge. Using mass spectrometry-based label-free quantitative proteomics, we identified 1402 seminal plasma proteins, and 44 proteins (20 up- and 24 downregulated) were found to be differentially abundant between infected and control males. Most differentially abundant proteins were involved in the immune response mechanisms, such as acute phase response, complement activation and coagulation, inflammation, lipid metabolism, cell-cell and cell-matrix adhesion, creatine-phosphate biosynthesis and germ cell-Sertoli cell junction signaling. Bacterial infection also caused profound changes in expression of selected genes in the testis and hematopoietic organs, which contributed to changes in seminal proteins. The altered seminal proteins and bacterial proteins in seminal plasma may serve as valuable markers of infection in the testis

Glycoprotein changes in the intestinal mucus of gilthead sea bream Sparus aurata parasitized by Enteromyxum leei (Myxozoa)

15th International Conference on Diseases of Fish and Shellfish celebrado en Splitz del 12 al 16 de septiembre 2011.The mucus layer that covers the intestinal epithelium, mainly mucine glycoproteins, acts as a barrier against enteric pathogens, and at the same time host-parasite interactions take place at this surface. Modulated mucus secretion, including changes in the glycosylation pattern, has been reported for several infectious diseases [1]. Enteromyxum leei is an enteric parasite affecting several aquarium and farmed marine fish. In gilthead sea bream (GSB), this myxosporean leads to severe enteritis, with emaciation and often with lethal consequences [2]. In the present study, the biochemical properties of isolated intestinal mucins of GSB infected by Enteromyxum leei were analysed. Mucus of the anterior (Ai), middle (Mi) and posterior (Pi) intestine was isolated from control-unexposed (C) and recipient experimentally infected (R) fish and concentrated by ultrafiltration prior to downward gel chromatography. Carbohydrate and protein content were determined for each molecular size fraction and their glycosylation degree calculated. Terminal glycosylation of the mucin glycoproteins was analysed via a lectin-binding assay. Additionally, adhesion of Aeromonas hydrophila and Vibrio alginolyticus to the isolated mucin glycoproteins was measured in order to detect variations of bacterial adhesion to the modulated mucus secretion. Biphasic elution profiles were obtained for both, protein and carbohydrate contents of mucin glycoproteins. Pi mucins presented a higher glycosylation degree than those in Ai and Mi. A reduction of glycoprotein content and changes among their terminal monosaccharides were found in R fish. A statistically significant reduction of bacterial adhesion to glycoproteins of R fish occurred for all intestine segments. Data from this study indicate that E. leei-parasitized GSB undergo a modulation in their intestinal mucus secretion. Mucus depletion may arise as a side effect of mucin secretion for parasite removal [1]. Variations in glycoprotein content and glycosylation pattern in the intestinal mucus of infected fish could be the consequence of a modified mucin and carbohydrate expression and might have implications in the reduced bacterial adhesion to mucus as a host derived mucosal response. Further studies are still needed to elucidate the specific role of host mucins in recognition and penetration of the parasite.Peer Reviewe

Stunning of common carp: Results from a field and a laboratory study

Abstract Background Common carp Cyprinus carpio is an important food fish in Central Europe, which in some regions is consumed as part of local tradition. The majority of carp are sold by small retailers and not processed in commercial processing plants. The overall objective of this study was to monitor how animal welfare is safeguarded during the stunning and slaughtering of carp for retail sale. For this, the stunning and slaughtering process was monitored on 12 carp farms. Four welfare-related parameters were assessed: (i) stunning success, (ii) injuries related to the applied stunning method, (iii) time between stunning and slaughter, and (iv) visible responses of carp during slaughtering. In addition, indicators of physiological stress were measured. In order to analyse whether the absence of behavioural indicators of consciousness after electrical stunning was correlated with unconsciousness a complementary laboratory study was performed. Here, carp were exposed to electrical current densities between 0.09 and 0.41 A/dm2. The presence of behavioural responses and visually-evoked responses (VER) in the electro-encephalogram in response to light flashes as indicators for an absence of consciousness was recorded. Results The carp farms applied manual percussive (18%) or electrical (23%) stunning methods, while the majority of farms used a combination of electrical stunning immediately followed by manual percussive stunning (59%). In the latter condition, 92.6% of stunned carp displayed no behavioural indicators of consciousness and significantly fewer injuries related to mishits compared to sole percussive stunning. In the laboratory study, behavioural indicators of consciousness recovered in carp between 1 and 9 min following removal of the electrical current. However, VER could be recorded already at 30 ± 8 s post stunning. This indicates a fast recovery of carp from electrical stunning when exposed to current densities in the range of those generated by commercially available stunning instruments for fish. Conclusions Under field conditions, percussion (applied manually) and electrical stunning might be poor inducers of unconsciousness before slaughter, while a combination was most effective. In order to undertake improvements in electrical stunning, further investigations into the current density, required for inducing prolonged insensibility in carp during electrical stunning, are needed

Koi-Herpesvirus Übertragung vom Laichkarpfen zur Brut?: Untersuchungen zur Risikobewertung der Übertragung des Koi-Herpesvirus durch Laichkarpfenbestände zur Sicherung nachhaltiger Sanierungserfolge der KHV-I in Sachsen und im Hinblick auf die Erhaltung der genetischen Vielfalt der Laichfischbestände in Sachsen

Im Bericht wird bisher ungeklärten Fragen des Übertragungswegs des Koi-Herpesvirus nachgegangen. In latent infizierten Laichkarpfenbeständen, in deren Geschlechtsprodukten und in befruchteten Eiern lässt sich das Virus (KHV) nachweisen. Eine Infektion der frisch geschlüpften Karpfenbrut scheint allerdings nicht zu erfolgen. Brütlinge von Laichfischen, die aus KHV-positiven Beständen stammen, haben eine höhere Resistenz gegenüber einer erneuten Infektion mit dem KHV. Der Beitrag richtet sich an praktische Fischzüchter, Fachtierärzte, Fischereiwissenschaftler und an die interessierte Öffentlichkeit. Redaktionsschluss: 31.03.202

Koi-Herpesvirus Übertragung vom Laichkarpfen zur Brut?: Untersuchungen zur Risikobewertung der Übertragung des Koi-Herpesvirus durch Laichkarpfenbestände zur Sicherung nachhaltiger Sanierungserfolge der KHV-I in Sachsen und im Hinblick auf die Erhaltung der genetischen Vielfalt der Laichfischbestände in Sachsen

Im Bericht wird bisher ungeklärten Fragen des Übertragungswegs des Koi-Herpesvirus nachgegangen. In latent infizierten Laichkarpfenbeständen, in deren Geschlechtsprodukten und in befruchteten Eiern lässt sich das Virus (KHV) nachweisen. Eine Infektion der frisch geschlüpften Karpfenbrut scheint allerdings nicht zu erfolgen. Brütlinge von Laichfischen, die aus KHV-positiven Beständen stammen, haben eine höhere Resistenz gegenüber einer erneuten Infektion mit dem KHV. Der Beitrag richtet sich an praktische Fischzüchter, Fachtierärzte, Fischereiwissenschaftler und an die interessierte Öffentlichkeit. Redaktionsschluss: 31.03.202

Effects of Enteromyxum leei (Myxozoa) infection on gilthead sea bream (Sparus aurata) (Teleostei) intestinal mucus: Glycoprotein profile and bacterial adhesion

The intestinal myxosporean parasite Enteromyxum leei causes severe desquamative enteritis in gilthead sea bream (Sparus aurata) (Teleostei) that impairs nutrient absorption causing anorexia and cachexia. In fish, as in terrestrial vertebrates, intestinal goblet cells are responsible for the adherent mucus secretion overlying epithelial cells, which constitutes a first line of innate immune defense against offending microorganisms but serves also as substrate and nutrient source for the commensal microflora. The secreted intestinal mucus of parasitized (n = 6) and unexposed (n = 8) gilthead sea bream was isolated, concentrated, and subjected to downward gel chromatography. Carbohydrate and protein contents (via PAS and Bradford stainings), terminal glycosylation (via lectin ELISA), and Aeromonas hydrophila and Vibrio alginolyticus adhesion were analyzed for the isolated intestinal mucins. Parasitized fish, compared with unexposed fish, presented intestinal mucus mucins with a lower glycoprotein content and glycosylation degree at the anterior and middle intestine, whereas both glycoprotein content and glycosylation degree increased at the posterior intestine section, though only significantly for the total carbohydrate content. Additionally, a slight molecular size increase was detected in the mucin glycoproteins of parasitized fish. Terminal glycosylation of the mucus glycoproteins in parasitized fish pointed to an immature mucin secretion (N-acetyl-α-d-galactosamine increase, α-l-fucose, and neuraminic-acid-α-2-6-galactose reduction). Bacterial adhesion to large-sized mucus glycoproteins (>2,000 kDa) of parasitized fish was significantly lower than in unexposed fish. © 2012 Springer-Verlag Berlin Heidelberg.This work was funded by the Spanish Ministry of Science and Innovation (MICINN) through the project AGL2009-13282-C02-01. Additional funding was obtained from the Generalitat Valenciana (research grants PROMETEO 2010/006, ISIC 2012/003).Peer Reviewe