EXCISION OF THE POLYDNAVIRUS CHROMOSOMAL INTEGRATED EP1 SEQUENCE OF THE PARASITOID WASP COTESIA-CONGREGATA (BRACONIDAE, MICROGASTINAE) AT POTENTIAL RECOMBINASE BINDING-SITES

Cotesia congregata polydnavirus (CcPDV) is essential for successful pa rasitism of Manduca sexta larvae by the braconid wasp Cotesia congrega ta. To determine the molecular mechanisms for the vertical transmissio n of CcPDV in the wasps, we analysed the different forms of the vi rus sequences containing the gene encoding the early parasitism-specific protein 1 (EP1), By a detailed molecular analysis, we demonstrated tha t the EP1 sequences are present in wasp DNA in two forms: a circular f orm as seen in the virus particles and a form integrated into the wasp genome, Moreover, we showed that the integrated form of the EP1 seque nces is able to excise in the ovary cells, A fragment corresponding to an EP 1 'empty locus' (without the viral sequence) was PCR-amplified from ovarian DNA. Comparison of the sequences isolated from the EP1 ci rcle, the integrated form and the empty locus revealed that the extrem ities of the EP1 genomic sequences constitute a direct repeat, Strikin gly, these sequences contain a potential binding site for a recombinas e of the Hin family located in close vicinity to the position where th e DNA strand exchange occurs. Thus, the data bear upon the possibility that the bracovirus circles are excised via a mechanism related to th e Hin mediated Conservative Specific-Specific Recombination (CSSR) of prokaryotes.