Figure 6

Syncytin-1 but not MSRV Env, Xq22.3 Env FLΔStop, or Xq22.3 Env induces syncytia in HeLa cells. HeLa cells were transfected with the indicated HERV-W Env constructs and subsequently stained with May-Grünwald and Giemsa solutions to visualize syncytia formation. Multinucleated giant cells (syncytia) were only detectable in cells transfected with Syncytin-1. Magnification × 250.