Identification and characterization of cauliflower mosaic virus replication complexes--analogy to hepatitis B viruses

Putative replication complexes of cauliflower mosaic virus (CaMV) which resemble hepatitis B virus replication complexes in several respects have been identified. The CaMV replication complexes contain a heterogeneous population of minus-strand DNA ranging in size from less than 600 nucleotides to full genome length of 8000 nucleotides. The minus-strand DNA of these replication complexes is largely single stranded or in a DNA/RNA hybrid structure. All of the plus-strand DNA within the complexes is in a DNA duplex which contains regions of single-stranded minus-strand DNA. These DNAs appear to be replication intermediates arising from reverse transcription of the CaMV 35 S RNA and to be encapsidated into virions or virion-like particles. The same fractions from sucrose density gradients that contain the putative replication intermediates also contain an enzymatic activity that incorporates deoxyribonucleotide triphosphates in both minus- and plus-strand CaMV DNA. This replication activity is consistent with a reverse transcription model for CaMV replication based on results which demonstrate that incorporation of deoxyribonucleotides into minus-strand DNA is refractory to actinomycin D while incorporation into plus-strand DNA is inhibited by the drug.