tokens: Reversions or additional mutations were not detected in the U3 and R regions of proviral DNA from CEMxl74 cells infected with the SIVmac239 mutants .
folded_tokens: reversions or additional mutations were not detected in the u3 and r regions of proviral dna from cemxl74 cells infected with the sivmac239 mutants .
labels: O O O O O O O O O O O O O O B-DNA_domain_or_region I-DNA_domain_or_region O B-cell_line I-cell_line O O O B-virus O O