Immunogen sequence: ILNELKPEQV EQLKLIMSKR YDGSQQALDL KGLRSDPDLV AQNIDVVLNR RSCMAATLRI IEENIPELLS LNLSNNRLYR LDDMSSIVQK APNLKILNLS G. The constitutive transport element (CTE) of type D retroviruses serves as a signal of nuclear export for unspliced viral