Abstract
After naturally recovered from the disease caused by Bombyx cytoplasmic-polyhedrosis virus (Bm CPV), Hyphantria cunea and Orgyia thyellina acquired a high resistance to the same virus spesies, Bm CPV, but their susceptibilities to other species of CPVs, nuclear-polyhedrosis viruses, and a granulosis virus were not different from those of the larvae uninfected previously with Bm CPV. Electron microscopical observation revealed that no sign of the replication of the secondary inoculated Bm CPV was detected in the midgut epithelium of the larvae which have been cured from Bomyx cytoplasmic-polyhedrosis, but secondary inoculated CPVs of the other species multiplied normally. These results suggested that the high resistance to virus infection acquired in the insects after natural recovery from Bombyx cytoplasmic polyhedrosis was specific against the infection of the same virus species, Bm CPV.
