Physical maps of SfMNPV baculovirus DNA and its genomic variants.

Spodoptera frugiperda MNPV was plaque-purified, and the viral DNA from the plaque-purified isolates was analyzed with restriction endonuclease enzymes. Seven distinct variants were identified when the DNA of the isolates were analyzed by EcoRI and HindIII. The DNAs of the SfMNPV predominant type (prototype) and the variants were mapped with BamHI, BglII, BstEII, EcoRI, HindIII, KpnI, and PstI by multiple enzyme digestion and blot hybridization. The cleavage sites generated by the seven restriction enzymes were ordered, and the sites were assigned map coordinates using a least-squares procedure. Since Autographa californica MNPV-E2 EcoRI fragment I, which contains the polyhedrin gene, hybridized with SfMNPV EcoRI fragment P, the physical map of SfMNPV was oriented with EcoRI P on the left, with site 1 being the EcoRI site between fragments F and P. The calculated genome size was 121.76 kilobase pairs or 80.36 X 10(6) Da. The DNA from each variant was compared to the DNA of the prototype for insertions, deletions, and new restriction sites. Physical maps were generated for each of the variants. The differences between the variant and the prototype were confined to four regions in the SfMNPV genome representing less than 16% of the prototype genome.