At about 48 h after infection (MOI 0.001), cells were harvested and incubated first with anti-GPC mAbs specific for different GPC epitopes or a negative control mAb specific for HIV-1 envelope (Env) glycoprotein (PGT-145) after which the cells were fixed and permeabilized for detection of intracellular VSV N. Over 90% of the cells stained with anti-GPC antibodies were positive for both intracellular VSV N and the cell-surface LASV glycoprotein. This evidence concerns the gene ERVW-1 and infection.