The U3 region of the long terminal repeat of a subgroup A transformation-defective rous sarcoma virus (tdPH2010) converts a noncytopathic virus to a cytopathic virus

Molecular characteristics of the complete genome of a J-subgroup avian leukosis virus strain isolated from Eurasian teal in China

The J-subgroup avian leukosis virus (ALV-J) strain WB11098J was isolated from a wild Eurasian teal, and its proviral genomic sequences were determined. The complete proviral sequence of WB11098J was 7868 nt long. WB11098J was 95.3.9 % identical to the prototype strain HPRS-103, 94.2 % identical to the American strain ADOL-7501, 94.5-94.7 % identical to Chinese broiler isolates, 94.8-97.5 % identical to layer chicken isolates, and 94.4-95.0 % identical to Chinese local chicken isolates at the nucleotide level. Phylogenetic analysis showed that the WB11098J isolate shared the greatest homology with the layer strain SD09DP03 and was included in the same cluster. Interestingly, two 19-bp insertions in the U3 regions of the 5'LTR and 5'UTR that were most likely derived from other retroviruses were found in the WB11098J isolate. These insertions separately introduced one E2BP-binding site in the U3 region of the 5'LTR and a RNA polymerase II transcription factor IIB and core promoter motif of ten elements in the 5'UTR. A 5-bp deletion was identified in the U3 region of the 5'LTR. No nucleotides were deleted in the rTM or DR-1 regions in the 3'UTR. A 1-bp deletion was detected in the E element and introduced a specific and distinct binding site for c-Ets-1. Our study is the first to report the molecular characteristics of the complete genome of an ALV-J that was isolated from a wild bird and will provide necessary information for further understanding of the evolution of ALV-J.

A single amino-acid substitution in gag p19 protein (MA) of Rous sarcoma virus suppresses virus production from infected cells

Gag p19 protein (MA) of the transformation-defective Rous sarcoma virus mutant, tdPH2010, has a point mutation at nucleotide 376 (G to A) that results in an amino-acid change at residue 126 of p19 (Glu to Lys). This single amino-acid change is the cause of the aberrantly fast migration of this protein on SDS-polyacrylamide gels. To study the biological significance of the mutation, we introduced this mutation into a transformation-defective derivative of the molecularly cloned Rous sarcoma virus, SRA2, and examined its effect on virus replication. The virus possessing the mutation in its gag p19 gene had 50% slower replication as measured by the amount of reverse transcriptase as well as gag p27 protein (CA) in the culture media. Glu at position 126 appears to be important for efficient production of Rous sarcoma virus in vitro.