Reovirus designated as Mud crab reovirus (MCRV) is associated with the mass mortalities of mud crabs resulting
in significant economic loss to crab and shrimp-mud crab polyculture farmers in the Nagayalanka, Krishna
district, Andhra Pradesh. The 100 % chronic mass mortalities have been attributed to the outbreak of Mud crab
reovirus (MCRV) in the polyculture farms. The moribund crabs showed autotomy, discoloration of carapace, loss
of appetite, slow movement and loose gills. Histopathological observations of the infected mud crabs showed an
atrophied hepatopancreas, complete degeneration of tissues along with viral inclusions in hepatopancreas, gills
and muscles. Further analysis using Transmission electron microscopy (TEM), showed that the viral particles had
a diameter of 70 nm and exhibited a non-enveloped, icosahedral shape arranged in a crystalline manner. The
virus mainly infects the connective tissue of hepatopancreas, gills, muscle and develops in the cytoplasm. RT-PCR
reconfirmed the presence of reovirus in the hepatopancreas of spontaneously infected mud crab Scylla serrata.
The current study shows the importance of monitoring the MCRV prevalence in polyculture farms to minimize its
spread and precautionary measures can be taken by screening the brooders from the crab hatchery and stocking
of wild crabs without screening should be avoided in order to prevent MCRV outbreak.