Changes in DNA Polymerase Activities in Pupae of the Silkworm Bombyx mori after Infection with Nuclear Polyhedrosis Virus

Abstract
Changes in DNA polymerase activities were studied in pupae of the silkworm Bombyx mori upon infection with nuclear polyhedrosis virus (BmNPV). Two effects were observed in male and female pupae after inoculation of BmNPV: a marked increase in cellular .alpha.-polymerase activity and the induction of a new DNA polymerase (BmNPV-polymerase). Activities of both DNA polymerases, .alpha. and BmNPV, in the infected pupae increased in parallel, reached a maximum at 72 h post-inoculation and decreased subsequently. The virus infection did not affect the activity of .gamma.-polymerase in the pupae. An increased activity of .beta.-polymerase in the pupae was detected at the late stage of the infection cycle prior to pupal death. The possible roles of the DNA polymerases in BmNPV replication are discussed.