APHIDICOLIN INHIBITION OF THE PRODUCTION OF REPLICATIVE-FORM DNA DURING BOVINE PARVOVIRUS INFECTION

Since parvoviruses apparently do not possess a DNA polymerase activity, one or more of the host cell DNA polymerases must be responsible for replicating the single-stranded DNA genome. This study determines which polymerase, alpha, beta or gamma (pol.alpha., pol.beta. or pol.gamma., respectively), is responsible for the first step in bovine parvoviral DNA replication: conversion of the single-stranded DNA genome to a parental replicative form (RF). Aphidicolin, a specific inhibitor of DNA pol.alpha., was used to assay for the requirement of pol.alpha. activity in parental RF formation in vivo. Synchronized [bovine fetal lung] cell cultures were infected with bovine parvovirus with or without amphidicolin, and the products of viral replication were separated on agarose gels and identified by Southern blot analysis. Complete inhibition of viral DNA synthesis resulted when 20 .mu.M was present throughout the infection. Viral DNA synthesis was inhibited by as little as 1 .mu.M aphidicolon; lower concentrations (0.1 and 0.01 .mu.M) resulted in partial inhibition of the replication process. Using 32P-labeled bovine parvovirus as the input virus, parental RF were differentiated from daughter RF and progeny DNA synthesis. Evidently, DNA pol.alpha. is required for the production of RF during bovine parvovirus replication in vivo and this requirement is most likely for the conversion of bovine parvovirus input single-stranded DNA to parental RF These results do not rule out a possible role for DNA poly.gamma. in the first step, nor do they rule out a role for pol.alpha. or pol.gamma. in later stages of the replication cycle.