The endogenous Drosophila melanogaster retrovirus gypsy can propagate in Drosophila hydei cells

The endogenous Drosophila melanogaster retrovirus gypsy (mdg4) forms virus- like particles (VLPs) which are found as extracellular particles in the med ium used to culture D. melanogaster cells. The D. hydei somatic cell line D H14, which does not harbour gypsy sequences, was exposed to D. melanogaster VLPs. Subsequent PCR and Southern analysis revealed that gypsy elements ha d penetrated into the D. hydei cells, suggesting interspecific transmission of the retrovirus. A D.hydei cell line containing gypsy sequences was esta blished and grown in a mixed culture together with the G418-resistant D. hy dei cell line DH33, and gypsy was shown to be transmitted from cell to cell . The proportion of cells carrying gypsy increased with time. The rate of g ypsy invasion of the lines DH14 and DH33 was 10(-3) and 10(-2) per cell per generation, respectively. The results demonstrate the possibility of inter specific horizontal transfer of gypsy in the form of its VLPs.