Fig. 1

ELISA detection of serum antibodies reactive against the ENTV-1 envelope protein and causing neutralization of an ENTV-1 envelope protein pseudotyped retroviral vector. Sheep serum samples were evaluated in an indirect ELISA using purified ENTV-1 envelope (ESU-IgG) protein as the target antigen. The dashed line represents the background cut off value generated using serum from SPF sheep. The solid line with circular points represents results from the sheep that seroconverted following ENTV-1 infection and the dotted line with square points is representative of a non-seroconverter. ENTV-1 envelope pseudotyped MLV particles carrying the human placental alkaline phosphatase reporter gene were incubated with the indicated serum samples prior to infection of NIH 3T3/LL2SN cells [11]. The percent reduction in hPLAP positive foci is graphed