Expression of the Provirus from the Host-Cell Genome

Host-cell enzymes (such as RNA polymerase II) are now used by the integrated virus to express the gag, pal, and env proteins from spliced RNA transcripts. A splice-donor signal (AGGT) at nucleotides 203-206 downstream of the 5’ LTR is used in conjunction with splice-acceptor (sa) sites in the genome, principally a major 3’ splice site at about 6 kbp into the MoMLV
genome, upstream of the env sequences. Full-length transcripts of viral RNA are also produced, beginning at the start of the R region in the 5’ LTR and terminating at the end of the R region in the 3’ LTR.