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SUMMARYCydia pomonella granulosis viruses (CpGV) from seven different sources in Europe, America and New Zealand were compared by restriction enzyme analysis. Most samples were indistinguishable from the Mexican isolate (CpGV-M). Isolates from Russia (CpGV-R) and England (CpGV-E) showed small genotypic differences. CpGV-E was shown to be a mixture of two variants, E1 and E2. CpGV-E1 was indistinguishable from CpGV-M. A physical map of CpGV-M was constructed for the enzymes EcoRI, BamHI, HindIII, Sinai and ApaI. A comparison of fragment profiles allowed construction of maps for CpGV-R and CpGV-E2. Relative to CpGV-M, CpGV-R had a single deletion of 2.4 kbp and CpGV-E2 was modified in one area resulting in an additional EcoRI site, a shift in a BamHI site and in total about 1 kbp more DNA. The map was orientated by locating the granulin gene using the cloned granulin gene from Trichoplusia ni GV as a probe. There was no significant difference between the infectivities of the Mexican, Russian and English isolates for neonate larvae.

Hr1a consists of two 30-bp imperfect palindrome sequences separated by 58 bp and each palindrome contains a naturally occurring EcoRI site at its core. Plasmid subclones of the hr1a-containing AcMNPV HindIII-N fragment were examined for their ability to replicate in virus-infected (Spodoptera frugiperda) Sf9 cells, and to stimulate transcription when linked in cis with a 39K gene promoter-beta-glucuronidase fusion and cotransfected into cells along with a plasmid (ple-1) containing the gene encoding the trans-acting factor IE-1. Only those plasmids containing hr1a underwent infection-dependent replication and were able to stimulate transcription. Sequences mapping to the left of hr1a were required for maximal levels of replication. A single palindrome from hr1a was sufficient for supporting plasmid replication and for stimulating transcription, although both activities were more efficient when both palindromes were present. Plasmids containing only one-half of a palindrome or disruptions of the central EcoRI core either did not replicate, or replicated very poorly, and did not exhibit enhanced transcriptional activity from the 39K gene promoter. Gel retardation experiments showed that labeled hr1a-containing DNA fragments had retarded migration after incubation with extracts from cells transfected with ple-1. Supershift experiments using polyclonal antibodies to IE-1 indicated that IE-1 is a component of the protein complex bound to hr1a. Fragments containing disruptions of the EcoRI-core still bound IE-1, as shown by gel retardation assays, indicating that IE-1 binding alone is not sufficient to allow replication and transcriptional enhancement.

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