Identification and nucleotide sequence of the regions of Autographa californica nuclear polyhedrosis virus genome carrying insertion elements derived from Spodoptera frugiperda

Abstract

A morphology mutant of the baculovirus Autographa californica nuclear polyhedrosis virus called M5 was previously shown to synthesize two size classes of viral DNA, one of which had a deletion of 42% of the genome. It was hypothesized that the presence of the smaller M5 circular DNA resulted from the specific deletion of the region located between two sites carrying short DNA insertions. These sites have now been identified by DNA-DNA hybridization using cloned EcoRI fragments of M5 DNA. One cloned M5 EcoRI fragment was found to correspond to the deletion junction fragment where sequences from the insertion site in the 2.6-map unit region were covalently linked to sequences from the insertion site in the 46-map unit region. The 2.6- and 46-map unit regions of Wt AcMNPV DNA were sequenced. Potential long open reading frames which would be disrupted by the M5 inserts were detected. Nucleotide sequence analysis of the same regions of M5 DNA revealed the presence of almost identical inserts of 290 bp. The primary sequence of the inserts revealed characteristics similar to the termini of transposons. Hybridization studies suggested that the inserts were derived from repetitive elements of the Spodoptera frugiperda host cell genome.