Browsing by Author "Costa, Janina Z."
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- Detection of Betanodavirus in experimentally infected European seabass (Dicentrarchus labrax, Linnaeus 1758) using non‐lethal sampling methodsPublication . Ferreira, Inês Almeida; Costa, Janina Z.; Macchia, Valeria; Thompson, Kimberly Dawn; Baptista, TeresaOne of the major disease threats affecting the Mediterranean aquaculture industry is viral encephalopathy and retinopathy (VER). The target organs for Betanodavirus detection are the brain and eyes, obtained through lethal sampling. This study aimed to evaluate the efficacy and suitability of non‐lethal samples for detecting Betanodavirus in European seabass (Dicentrarchus labrax). European seabass juveniles were infected with Betanodavirus, by either an intramuscular injection or immersion (107 TCID50/ml and 106 TCID50/ml, respectively), and samples collected 7, 15 and 30 days post‐infection (dpi). The brain was collected as a lethal sample, and gills, caudal fin and blood as non‐lethal tissues for detecting Betanodavirus by quantitative reverse transcription PCR (RT‐qPCR). The presence of virus in non‐lethal tissues was inconsistent, with lower viral loads than in the brain. For blood, higher viral loads were detected in intramuscular‐infected fish at 15 dpi until the end of the challenge. Serum antibodies against Betanodavirus were assessed using an enzyme‐linked immunosorbent assay (ELISA). Antibodies were detected as early as 7 dpi, with higher mean antibody titres at 15 and 30 dpi. The presence of Betanodavirus‐specific antibodies indicates that this is a suitable evaluation method for detecting early stages of the infection.
- Early immune modulation in European Seabass (Dicentrarchus labra) juveniles in response to Betanodavirus infectionPublication . Vaz, Mariana; Pires, Damiana; Pires, Pedro; Simões, Marco; Pombo, Ana; Santos, Paulo; Carmo, Beatriz do; Passos, Ricardo; Costa, Janina Z.; Thompson, Kim D.; Baptista, TeresaThe early host–pathogen interaction between European seabass (Dicentrarchus labrax) and Betanodavirus was examined by using juvenile fish infected intramuscularly with RGNNV (red-spotted grouper nervous necrosis virus). The time course selected for sampling (0–144 h post-infection (hpi)) covered the early stages of infection, with hematological, antioxidant and immunological responses examined. Early activation of the host’s immune system was seen in the first few hours post-infection (6 to 9 hpi), as evidenced by an increase in tnfa, cd28 and c3 expression in the head kidney of infected fish. Most hematological parameters that were examined showed significant differences between sampling times, including differences in the number of thrombocytes and various leukocyte populations. The plasma lysozyme concentration decreased significantly over the course of the trial, and most antioxidant parameters examined in the liver showed significant differences over the infection period. At 144 hpi, peak expression of tnfa and il-1b coincided with the appearance of disease symptoms, peak levels of virus in the brain and high levels of fish mortality. The results of the study show the importance of analyzing the early interactions between European seabass and Betanodavirus to establish early indicators of infection to prevent more severe outcomes of the infection from occurring.