High amplification of a densovirus-derived vector in larval and adult tissues of Drosophila

The Lepidopteran densovirus-derived vector, pJlacZ Delta NS3, is a defectiv e virus genome with an insertion of lacZ DNA in the viral structural protei n coding sequence, and a deletion of the sequence coding the non-structural polypeptide NS3. pJlacZ Delta NS3 was injected into Drosophila eggs and th e maintenance of the viral genome was monitored by expression of beta -gala ctosidase and by Southern blot hybridizations. Intense beta -galactosidase activity was observed in many somatic tissues of third-instar larvae and ad ult flies, in more than 60% of the injected animals. DNA analyses showed th at staining in adult tissues correlated with the amplification of the vecto r. Together, these results suggest the occurrence of early events of integr ation of the vector into the Drosophila host genome.