Detection of infectious pancreatic necrosis virus in infected trout by an immunodot assay

Two monoclonal antibodies (MAbs) which react with different structural prot eins of infectious pancreatic necrosis virus (IPNV) were used to perform an immunodot diagnostic assay. The MAb 1, which reacts with Vp3/4, gave sligh tly stronger signals than the MAb 14 directed against Vp2, the major struct ural protein of the virus. Both MAbs reacted with the widespread IPNV serot ypes VR299, Sp and Ab. The production of viral antigens in CHSE-214 culture d cells infected at a low multiplicity of infection was followed with the M Ab 1. Positive signals were detected after 16 hours post infection. The met hod was tested with infected trout (Onchorynchus mykiss). Extract of homoge nized whole animals were tested directly or after performing an amplificati on step in CHSE-214 cells. Samples from fish showing symptoms of the diseas e gave clear dot signals when assayed directly. In order to detect the viru s in fish which recover from the disease, thus, putative virus carriers, CH SE-214 cells were infected with the fish extracts. Only one day was require d to obtain positive signals in all the animals tested. In addition, the co lor intensity of the dots correlated well with time course of the infection in the fish.