Interestingly, homologous recombinants were generated only during infection involving MatH-HVR-BMV. Fiftyfive percent of analyzed lesions contained the RNA3 recombinant. In all sequenced recombinants, one HVR and the spacer were deleted ( Figure 5C ). Their 3 0 -UTR was composed of a 295 nt RNA1-derived sequence and HVRs followed by To test the recombination activity of HCV-derived sequences X and HVR the following Mat0-RNA3 derivatives were prepared: MatH-X-RNA3-with two copies of X in sense orientation (3 0 and 5 0 Xs), MatNH-X-RNA3-with two copies of X located in different orientation (3 0 Xs and 5 0 Xas), MatH-HVR-RNA3-containing two copies of HVR in sense orientation (3 0 and 5 0 HVRs) and MatNH-HVR-RNA3-with two copies of HVR, 3 0 -copy in sense and 5 0 in antisense orientation (3 0 HVRs and 5 0 HVRas). MatH-X-and MatH-HVR-RNA3 were applied to test X's and HVR's ability to support homologous crossovers while MatNH-X-and MatNH-HVR-RNA3 were applied to examine X's and HVR's competence to induce non-homologous, heteroduplex-mediated recombination. RF, recombination frequency observed during infection involving each RNA3 derivative. (C). Homologous recombinants generated during infection involving MatH-HVR-BMV. RNA3 recombinants were only formed during MatH-HVR-BMV infection. In all of them, one recombinationally active sequence HVRs and a spacer were deleted and their 3 0 -UTR was composed of RNA1 derived sequence and HVRs followed by the CP coding region. Because crossovers occurred within identical regions, the location of recombinant junction sites could not be precisely The presence of homologous and non-homologous recombinants in the examined lesions was always confirmed not only by RT-PCR but also by northern blot analysis ( Figure 6 ). This revealed the same tendency as that observed earlier using the heteromolecular system (30, 33) . BMV accumulated to a very low level in lesions containing parental RNA3 (original molecules with duplicated sequences- Figure 6A , lane 5 and Figure 6B , lane 2). However, this changed in lesions where a recombinant was generated ( Figure 6A , lanes 1-4 and Figure 6B, lanes 1 and 3) .