Swine testis (ST) cell lines producing a murine recombinant retrovirus (RRV) were established in order to transfer the bacterial lacZ gene fused to a nuclear location signal (nlslacZ) into animal cells. ST cells were infected with the supernatant of the cat G355.5LacZ2 cell line which produces amphotropic and xenotropic MMuLVSVnlslacZ-defective RRV and wild amphotropic and xenotropic MMuLV. Expression of the nlslacZ reporter gene was under the transcriptional control of both the SV40 early promoter and the retroviral LTR. ST cells expressing the reporter gene were sorted and cloned by limiting dilutions. Fourteen STLacZ-cell lines were isolated and subsequently tested for virus production. Depending on the host range of the retroviruses, two cell lines (STBF11 and STAA3) produced both a xenotropic recombinant pseudotype and wild retroviruses; another (STAB 10) produced both an amphotropic recombinant pseudotype and wild retroviruses. Southern blot analysis of the producer cell lines was carried out to verify proviral integration. The efficiency of the different pseudotypes in the transfer of the nlslacZ reporter gene to cultured animal cells, including porcine cells, was compared to the pseudotyped RRV produced by cat lines. Our results showed that the xenotropic RRV produced by the porcine STBF 11 cell line has a high titre for cells from different species and led to a higher number of porcine endothelial and lymphoblastoid cells expressing the reporter gene than did RRV produced by the cat packaging cell lines.