M-MuLV glyco-gag facilitates XMRV release. A) The organizations of M-MuLV glyco-gag expression plasmids are shown. In some cases the CTG (CUG) initiation codon for glyco-gag was changed to ATG (AUG) to enhance expression of glyco-gag. B) pVP62 and the glyco-gag expression vectors were co-transfected into 293 T cells and Gag proteins in the released viruses and the cell lysates were detected by SDS-PAGE and Western blots with anti-p30CA antibodies. The amount of viral release relative to control viruses is shown. Welch’s t-test with unequal variances was conducted to detect the difference between mean scores in the two groups and values significantly different from pVP62 alone (control) are indicated (*, p < 0.01).