Immunoserology of European seabass (Dicentrarchus labrax) and white grouper (Epinephelus aeneus) as a non-lethal diagnostic tool for viral nervous necrosis
- 60 Downloads
Viral nervous necrosis (VNN) is a lethal fish disease that has spread worldwide over the last two decades, causing severe losses in aquaculture. Diagnosis of the infection is generally made by sampling brain tissue, which involves sacrificing often valuable fish. Aiming at developing a non-lethal diagnostic method, the immune responses to an experimental nervous necrosis virus (NNV) infection in sea bass Dicentrarchus labrax and white grouper Epinephelus aeneus, two species most susceptible to the disease, were studied. RT-qPCR revealed presence of NNV in the fish brain within 24 h post-infection, the virus titer remaining high up to 30–35 days post-infection. In D. labrax blood, the virus was detectable within the first 5 days, after which its presence declined rapidly. Mx gene expression correlated to the virus presence in the blood and brain. An indirect ELISA was developed that quantified anti-NNV IgM in the fish blood. In D. labrax, anti-NNV IgM titer increased significantly within 5 days post-infection, and presence of specific IgM was detectable for 180 days. A sandwich ELISA was developed for E. aeneus. In this latter species, anti-NNV IgM titer increased significantly within the first 12 days and was detectable for 208 further days. The sandwich ELISA can be used as a diagnostic tool for detecting NNV exposure in all fish species for which specific antibodies against their IgMs are not yet commercially available. Our immunoserological method can reliably be used for diagnosis of VNN infection and does not require sacrificing the fish.
KeywordsBetanodavirus NNV Dicentrarchus labrax Epinephelus aeneus Diagnostics ELISA
We are very grateful to Prof. Moshe Kotler and Prof. Michael Steinitz, Department of Pathology, The Hebrew University, Hadassah Medical School, Jerusalem, for their authoritative guidance in the virology and immunology fields. We also thank Dr. Angelo Colorni, Department of Pathobiology, Israel Oceanographic and Limnological Research, National Center for Mariculture, Eilat, for his invaluable critical review of the manuscript. This work was carried out at the Green–Keiser Fish Health Center, IOLR–NCM, Eilat.
This study was financially supported by the Israeli Ministry of National Infrastructures (grant no. 894-0165-10) and the Jewish Colonization Association (ICA) funds (grant no. 02-11-16).
- Chaves-Pozo E, Guardiola FA, Meseguer J, Esteban MA, Cuesta A (2012) Nodavirus infection induces a great innate cell-mediated cytotoxic activity in resistant, gilthead seabream, and susceptible, European sea bass, teleost fish. Fish Shellfish Immunol 33:1159–1166. https://doi.org/10.1016/j.fsi.2012.09.002 CrossRefGoogle Scholar
- Glazebrook JS, Heasman MP, de Beer SW (1990) Picorna-like viral particles associated with mass mortalities in larval barramundi, Lates calcarifer Bloch. J Fish Dis 13:245–249. https://doi.org/10.1111/j.1365-2761.1990.tb00780.x CrossRefGoogle Scholar
- Jaramillo D, Hick P, Deece K, Tweedie A, Kirkland P, Arzey E, Whittington RJ (2016b) Comparison of ELISA formats for detection of antibodies specific for nervous necrosis virus ( Betanodavirus ) in the serum of immunized barramundi Lates calcarifer and Australian bass Macquaria novemaculeata. Aquaculture 451:33–38. https://doi.org/10.1016/j.aquaculture.2015.08.015 CrossRefGoogle Scholar
- Korsnes K, Karlsbakk E, Devold M, Nerland AH, Nylund A (2009) Tissue tropism of nervous necrosis virus (NNV) in Atlantic cod, Gadus morhua L., after intraperitoneal challenge with a virus isolate from diseased Atlantic halibut, Hippoglossus hippoglossus (L.). J Fish Dis 32:655–665. https://doi.org/10.1111/j.1365-2761.2009.01035.x CrossRefGoogle Scholar
- Novel P, Fernández-Trujillo MA, Gallardo-Gálvez JB, Cano I, Manchado M, Buonocore F, Randelli E, Scapigliati G, Álvarez MC, Béjar J (2013) Two mx genes identified in European sea bass (Dicentrarchus labrax) respond differently to VNNV infection. Vet Immunol Immunopathol 153:240–248. https://doi.org/10.1016/j.vetimm.2013.03.003 CrossRefGoogle Scholar
- Reed LJ, Muench H (1938) A simple method of estimating fifty per cent endpoints. Am J Epidemiol 27:493–497. https://doi.org/10.1093/oxfordjournals.aje.a118408 CrossRefGoogle Scholar
- Terlizzi A, Tedesco P, Patarnello P (2012). Spread of pathogens from marine cage aquaculture - a potential threat for wild fish assemblages under protection regimes? In: Carvalho ED, David GS, Silva RJ, (eds) Health and Environment in Aquaculture. InTech 403–414. https://doi.org/10.5772/30826
- Toffan A, Pascoli F, Pretto T, Panzarin V, Abbadi M, Buratin A, Quartesan R, Gijón D, Padrós F (2017) Viral nervous necrosis in gilthead sea bream (Sparus aurata) caused by reassortant betanodavirus RGNNV/SJNNV: an emerging threat for Mediterranean aquaculture. Sci Rep 7:46755. https://doi.org/10.1038/srep46755 CrossRefGoogle Scholar
- Vendramin N, Patarnello P, Toffan A, Panzarin V, Cappellozza E, Tedesco P, Terlizzi A, Terregino C, Cattoli G (2013) Viral encephalopathy and retinopathy in groupers (Epinephelus spp.) in southern Italy: a threat for wild endangered species? BMC Vet Res 9:1–7. https://doi.org/10.1186/1746-6148-9-20 CrossRefGoogle Scholar
- Yoshikoshi K, Inoue K (1990) Viral nervous necrosis in hatchery-reared larvae and juveniles of Japanese parrotfish, Oplegnathus fasciatus (Temminck & Schlegel). J Fish Dis 13:69–77. https://doi.org/10.1111/j.1365-2761.1990.tb00758.x CrossRefGoogle Scholar