EFFECT OF THE TURBOT AQUAREOVIRUS ON FISH MACROPHAGES USING AN IN-VITRO MODEL

The turbot aquareovirus TRV has an invasive behaviour, as the virus sp reads throughout most fish organs and tissues. In the present study th e presence of TRV inside macrophages of both naturally and experimenta lly infected turbot was demonstrated, and the ability of the virus to resist killing and to replicate within turbot macrophages in vitro was evaluated. The virus survived and replicated in the phagocytic cells, as demonstrated by electron microscopy and growth curve. Superoxide a nion (O-2(-)) production of phorbol 12-myristate 13-acetate (PMA)-stim ulated macrophages infected with TRV was similar to that of normal mac rophages. However, the levels of O-2(-) produced by macrophages infect ed with a non-virulent Aeromonas salmonicida strain lacking the A-laye r were clearly reduced when phagocytic cells had been previously incub ated with TRV, but this reduction did not modified the ability of infe cted macrophages to kill the bacteria. These results indicate that the viral agent eludes the recognition system of the macrophages and the bactericidal capacity of these phagocytic cells is not affected by the presence of the virus, although the interaction with the virus must a ffect the mechanism of reduction of molecular oxygen into O-2(-).