FIG. 6.

Infectivity and particle production of HERV-K viruses containing the K113 Gag I516M mutation. (A) Infectious titers of HERV-K particles produced by transfection of 293T cells with Rec, VSV-G, and the indicated CHKCG vectors. Producer cell supernatants were used to infect 293T target cells 48 h posttransfection, and GFP foci were counted 72 h postinfection and expressed as infectious units per milliliter (IU/ml). The data are means plus standard deviations (n = 4). (B) Western blot analysis of the producer cells used for panel A. Supernatants were collected, and whole-cell lysates were prepared at the time of target cell infection (48 h posttransfection). The approximately 75-kDa Gag precursor and 30-kDa processed CA proteins are indicated. Only the processed form was detected in the culture supernatants.