Betanodavirus genotypes produce clinical signs and mortality in the shi drum (Umbrina cirrosa), and infective particles are isolated from the damaged brain

The susceptibility of shi drum juveniles to betanodavirus increases with rearing densities in a process mediated by neuroactive ligand–receptor interaction

“…Interestingly, shi drum specimens at the larval stage or with a low bw are very susceptible to RGNNV ( 5 , 9 ); however, in this study, fish with a bw of 30 g and were reared at low density (2 kg/m 3 ) became asymptomatic, even after demonstrating infection, as shown by the expression of the viral CP in their tissues. The inverse relationship between susceptibility to NNV and bw observed in this work has already been described in many species ( 18 ).…”

“…The fact that the industrial culture of shi drum has not been consolidated yet could be due to some gaps on the knowledge about its biology, to technical problems, or to inadequate market promotion policies that dissuade enterprises to produce this species, among others ( 3 ). Although several aspects of shi drum biology have been studied since the 1990s, such as its reproduction, digestive system development, dietary requirements, and growth performance ( 9 ), its immunity or stress has only recently started to be assessed ( 9 – 11 ).…”

“…Under experimental conditions, shi drum juveniles of 10 g body weight (bw) were found susceptible to all NNV genotypes (RGNNV, SJNNV, BFNNV, and TPNNV), although the signs of the disease and lesions varied depending on the genotype ( 9 ). In general, VER disease is characterized by neurological abnormalities (e.g., erratic swimming and spiral movements with the belly up) and a distinct vacuolization of the nerve tissue (brain and retina) ( 19 , 28 ).…”

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“…The fact that the industrial culture of shi drum has not been consolidated yet could be due to some gaps on the knowledge about its biology, to technical problems, or to inadequate market promotion policies that dissuade enterprises to produce this species, among others (3). Although several aspects of shi drum biology have been studied since the 1990s, such as its reproduction, digestive system development, dietary requirements, and growth performance (9), its immunity or stress has only recently started to be assessed (9)(10)(11).…”

“…Under experimental conditions, shi drum juveniles of 10 g body weight (bw) were found susceptible to all NNV genotypes (RGNNV, SJNNV, BFNNV, and TPNNV), although the signs of the disease and lesions varied depending on the genotype (9). In general, VER disease is characterized by neurological abnormalities (e.g., erratic swimming and spiral movements with the belly up) and a distinct vacuolization of the nerve tissue (brain and retina) (19, 28).…”