Inoculation of BALB/c mice with fish-pathogenic nodaviruses

To investigate the pathogenicity of fish-pathogenic nodaviruses (betanodaviruses) in mammals, weanling mice were inoculated with striped jack nervous necrosis virus (SJNNV; the type species of the genus Betanodavirus) or redspotted grouper nervous necrosis virus (RGNNV), which belong to different genotypes. After inoculation with 10(7.5) TCID50, either intramuscularly or intraperitoneally, mice remained clinically normal for the 14-day observation period. In a subsequent short-term (72 h) experiment, mice inoculated intramuscularly with 10(7.5) TCID50 yielded virus (10(6) to 10(5) TCID50/g) from muscle at the site of injection at 3, 24 and 72 h post-infection; they also yielded virus from the kidneys (10(5) TCID50/g) at 3 and 24 h post-infection, but by 72 h virus had become almost undetectable at this site. Throughout the experiment, no virus was detected in the sites that are target organs of betanodaviruses in fish, namely, the brain, spinal cord and eye. The results indicate that the mouse is not susceptible to betanodaviruses.