FIG. 6.

SP-A is the site of JSRV_JS7 proviral integration. (A) JSRV_JS7-provirus is integrated in a reverse orientation to the 5′ untranslated region of SP-A exon 1. Both JSRV_JS7 and SP-A sequence fragments are shown to scale. Ovine SP-A exons are shaded and introns are white. US is a 25-nucleotide upstream “enhancer” region which shares high homology to sequences in human and baboon. (B) The boundaries of the integration site are shown in detail. Exon 1 is predicted to begin approximately 25 nucleotides downstream of the TATA box. Integration of JSRV_JS7 interrupts the proposed six-amino-acid exon 1 SP-A translation product. The dotted line represents the JSRV_JS7 provirus. GGCTGT is the retroviral target sequence duplicated by the host upon integration. Amino acids are indicated above some of the codons in the nucleotide sequences as follows: M, Met; G, Gly; C, Cys; V, Val; R, Arg; A, Ala. us, upstream; ds, downstream.