RESUMEN
We report the production and characterisation of three monoclonal antibodies to the prion protein (PrP) of Rainbow trout (Oncorhynchus mykiss), a piscine protein with characteristic structural features common to mammalian prion protein. All of the antibodies were used to detect PrP in ELISA, Western blot and by immunohistochemistry. The antibodies showed specificity for certain genera of the Salmonidae, binding to PrP of Rainbow trout and Atlantic salmon (Salmo salar) but not to that from Arctic char (Salvelinus alpinus). Using the immunoreagents in Western blots, we demonstrated that O. mykiss PrP protein is a 64 kDa protein present in brain, spinal chord and optic nerve. PrP was not detected in a range of peripheral tissues: eye, heart, stomach, intestine, liver, kidney, spleen, muscle and skin. Furthermore, PrP could be detected in all brain regions studied: optic lobe, cerebrum/olfactory lobe, cerebellum, hypothalamus/pituitary and medulla oblongata and was widespread within these tissues as determined by immunohistochemistry. These immunoreagents provide specific tools to study the biology of Rainbow trout and Atlantic salmon PrP and any possible transmissible spongiform encephalopathy-like disease of these economically important fish species.