FIG. 1.

JSRV expression constructs. (A) All constructs are driven by the CMV immediate-early promoter (bold arrows). The organization of the JSRV genome, along with its open reading frames, is detailed for the full-length provirus molecular clone of JSRV, pCMV2JS21. pTN3 has the majority of the env gene deleted, except for a portion that maps to the C terminus of Env. For the ΔGP deletions, deletions are shown as gaps. The nomenclature reflects amino acids deleted within the Env protein. The splice donor (sd) and splice acceptor (sa) nucleotide positions for the JSRV env transcript are indicated. The locations of the putative Env signal peptide (SP), the Env surface (SU) and transmembrane (TM) domains, and the Env membrane-spanning sequence (MS) and CT are shown. (B) The influenza virus HA epitope tag was fused immediately downstream of the Env CT domain for the JSRV Env and Env signal peptide expression constructs (ΔGPHA and ΔGPSPHA, respectively).