IN-VITRO AND IN-VIVO REPLICATION OF TURBOT AQUAREOVIRUS (TRV) IN TURBOT TISSUES

The replication of the turbot aquareovirus TRV in turbot tissues was s tudied in vitro in excised turbot tissues, and in vivo, following the evolution of viral titers in organs and tissues from experimentally in fected turbot fry. Replication of TRV in vitro was demonstrated in kid ney (with an increase of viral titer of more than 2 logs in 5 d), but also in liver and heart (increasing more than 1 log). Viral replicatio n was also demonstrated in vivo, with the kidney being the possible ta rget organ. The virus was detected in most tissues of turbot fry 2 h p ost infection, which suggests involvement of the circulatory system in the rapid spreading of the virus to all fish organs and tissues. It a ppears that stress conditions, and/or simultaneous occurrence of bacte rial infections, can enhance the replication of TRV in turbot, and the virus is more efficiently released to the environment. Our results su ggest that, under normal conditions, TRV shows low levels of replicati on in turbot tissues, and thus infected fish may behave as asymptomati c carriers, spreading the virus to the environment and healthy fish.