FlyFishMagazine's European operatives might have stumbled upon some key intelligence in the world of international fly fishing competition. Does anyone have any idea why the French are experimenting with "gypsy moth and spruce budworm nuclear polyhedrosis viruses ingested by rainbow trout?"
Rainbow trout fingerlings were fed dried krill injected with gypsy moth or spruce budworm nuclear polyhedrosis virus (LdNPV and CfNPV, respectively) at a total dose of 1.4 x 107 occlusion bodies (OBs) per fish.
The good news is that the trout did fine...
By the end of the 21-day experimental period there were no adverse effects on fish survival or behavior and no significant differences in feeding rates or growth between treated and control fish. The internal organs of all fish were examined at the end of the experiment and there were no signs of lesions, discoloration, swelling, hemorrhaging, or other aberrations.
Apparently it all has something to do with prime rib...
Visceral tissues were analyzed with a horseradish peroxidase-labeled whole genomic DNA probe (enhanced chemiluminescence procedure) to detect infection by the NPVs. There were no indications of NPV infection (no positive signals) in stomach and intestinal tract tissues of treated fish. High background signals were obtained from liver samples, but further analyses indicated that these were not due to the presence of LdNPV or CfNPV.
Perhaps the French are breeding some sort of Mayfly super race?
The protocols outlined here should be applicable to determining infectivity and effects of genetically modified insect viruses on fish.