Interaction of the attenuated recombinant rIHNV-Gvhsv GFP virus with macrophages from rainbow trout (Oncorhynchus mykiss)

11 pages, 7 figures

One of the most important threats to the salmonid aquaculture industry is infection caused by novirhabdoviruses such as infectious haematopoietic necrosis virus (IHNV) or viral haemorrhagic septicaemia virus (VHSV). Using reverse genetics, an avirulent recombinant rIHNV-Gvhsv GFP strain was generated, which was able to replicate as effectively as wild type IHNV in a fish cell line and in macrophages. Although this recombinant virus induced protective responses against IHNV and VHSV, the response did not involve the production of antibodies or modulate the expression of some antiviral genes. To determine the immune mechanisms underlying the protection conferred by the rIHNV-Gvhsv GFP virus, different immune parameters (NO production, respiratory burst activity and the induction of apoptosis) were assessed in the macrophage population. The results obtained in the present work may indicate that the Nv protein could be important in the modulation of NO and ROS production. rIHNV-Gvhsv GFP did not appear to have a clear effect on nitric oxide production or apoptosis. However, an increased respiratory burst activity (with levels induced by the recombinant virus significantly higher than the levels induced by the wild type virus), suggests a stimulation of the macrophage population, which could be related to the protection against virulent viruses.

This work was supported by the projects FAIRCT 98-4398 from the European Union and BIO 2000-0906 from the Spanish Ministerio de Ciencia y Tecnología. European structural funds were used for confocal microscopy. Fondo Europeo de Desarrollo Regional (FEDER) y Ministerio de Ciencia e Innovación. A. Romero acknowledges the CSIC for the I3P fellowship.

Peer reviewed