Determination of the titer of infectious LNCE in the presence of XMRV.

<p>The supernatant from DU145LNCE cells exposed to the medium from either DU145 (control medium) or DU145XMRV cells was applied in various dilutions to subconfluent cultures of naïve DU145 cells grown in 6-well plates. The treated cells were selected for G418 resistance and the surviving colonies were visualized by methylene blue staining. Neo-transducing particles were readily detectable in the supernatant of XMRV-exposed cells at 1,000-fold (panel A) and 10,000-fold (panel B), but not 100,000-fold (panel C) dilutions. The supernatant from DU145LNCE exposed to control medium was not toxic by itself (panel E), but it failed to transduce the resistance marker even when used without dilution (panel D).