Conventional identification of virus involves isolation of
viral genome followed by nested PCR, DNA-based detection
and symptomatic methods have the potential for widespread
application of in aquaculture[17]. Efforts to overcome these
problems have led to the development of immunoassay and
DNA-based symptomatic methods, including fluorescent
antibody tests (FAT), enzyme-linked immunosorbent assays
( ELISA ) , radioimmunoassay ( RIA ) , in situ hybridization
(ISH), dot blot hybridization (DBH) and polymerase chain
reaction (PCR) amplification techniques. The use of DNA-
based methods derives from the premise that each species
of pathogen carries unique DNA or RNA sequences that
differentiate it from other organisms.