Conversion of Friend mink cell focus-forming virus to Friend spleen focus-forming virus by modification of the 3' half of the env gene.
The 3' half of the env gene of the dualtropic Friend mink cell focus-forming virus was modified by replacing the restriction enzyme fragment of the genome DNA with the corresponding fragment of the acutely leukemogenic, polycythemia-inducing strain of Friend spleen focus-forming virus (F-SFFVP) genome DNA. Replacement with the fragment of F-SFFVP env containing the 585-bp deletion, the 6-bp duplication, and the single-base insertion converted the resulting chimeric genome so that the mutant had a pathogenic activity like that of F-SFFVP. Replacement with the fragment containing only the 585-bp deletion did not result in a pathogenic virus. However, when this virus pseudotyped by Friend murine leukemia virus was passaged in newborn DBA/2 mice, we could recover weakly pathogenic viruses with a high frequency. Molecular analysis of the genome of the recovered virus revealed the presence of a single-base insertion in the same T5 stretch where the wild-type F-SFFV env has the single-base insertion. These results provided evidence that the unique genomic structures present in the 3' half of F-SFFV env are the sole determinants that distinguish the pathogenicity of F-SFFV from that of Friend mink cell focus-forming virus. The importance of the dualtropic env-specific sequence present in the 5' half of F-SFFV env for the pathogenic activity was evaluated by constructing a mutant F-SFFV genome in which this sequence was replaced by the ecotropic env sequence of Friend murine leukemia virus and by examining its pathogenicity. The results indicated that the dualtropic env-specific sequence was essential to pathogenic activity.
Watanabe
N
N
Laboratory of Gene Technology and Safety, Institute of Physical and Chemical Research (RIKEN), Ibaraki, Japan.
Nishi
M
M
Ikawa
Y
Y
Amanuma
H
H
D000818:Animals; D003001:Cloning, Molecular; D004279:DNA, Viral / Q000235:genetics / Q000302:isolation & purification; D005260:Female; D005622:Friend murine leukemia virus / Q000235:genetics* / Q000472:pathogenicity; D015752:Genes, env; D007942:Leukemia, Experimental / Q000382:microbiology; D008297:Male; D051379:Mice; D008811:Mice, Inbred DBA; D008815:Mice, Inbred Strains; D008908:Mink Cell Focus-Inducing Viruses / Q000235:genetics* / Q000472:pathogenicity; D010957:Plasmids; D011995:Recombination, Genetic; D012091:Repetitive Sequences, Nucleic Acid; D015183:Restriction Mapping; D013155:Spleen Focus-Forming Viruses / Q000235:genetics* / Q000472:pathogenicity
D004279:DNA, Viral