Abstract
The susceptibility and the lethal time of infection by a nuclear polyhedrosis virus (NPV) were almost the same between silkworm larvae reared on artificial diets with or without containing of an antibiotic, chloramphenicol, indicating the antibiotic in artificial diet had no effect on NPV infection and multiplication in the fed larvae. On the other hand, the antibiotic in diet was great effective to prolong the lethal time of the fed larvae infected with a cytoplasmic-polyhedrosis virus (CPV). The prolongation of life was mainly due to the fact that the antibiotic in diet almost suppressed the abnormal multiplication of intestinal bacteria in the midgut lumen, which was usually accompanied by CPV infection.
