Isolation of the causative agent in mass mortality of wild Mullet in the Caspian Sea.
Confirmation of the isolated virus with Golden test through OIE recommended methods.
Positive result in pathogenicity test on Guppy fish in confirmation of isolated VNN.
TEM observation of VNN virus particles (25–30 nm) in infected and challenged fishes.
Observation of pathognomonic symptoms in clinical signs and histopathology findings.