Quantitative investigation of antigen and immune response in nervous and lymphoid tissues of Atlantic halibut (Hippoglossus hippoglossus) challenged with nodavirus

Abstract The present study reports the quantitative analysis of the spatio-temporal development of nodavirus infection and corresponding immune response in juvenile Atlantic halibut ( Hippoglossus hippoglossus ) challenged by intramuscular injection of nodavirus. Novel quantitative real-time RT-PCR protocols were applied to evaluate the absolute copy numbers of nodavirus RNA2 (RNA2) and secretory-IgM mRNA (sec-igμ) in the eye, brain, mid/posterior kidney and spleen sampled over a period of 81 days. In the eye and brain, levels of both RNA2 and sec-igμ increased significantly early in the infection. In the spleen and mid/posterior kidney, both RNA2 and sec-igμ were detected but the levels remained unchanged during the experimental period. The levels of RNA2 and sec-igμ in the eye and brain were strongly correlated ( P The results suggest that the nodavirus infection induced a significant antibody response through activation of B-cells in the kidney and spleen, and involved a substantial migration of antibody-secreting cells to infected peripheral tissues.