Fig 4.

Humoral immune response in genetically modified mice immunized with vectored MV expressing HCV structural proteins. Groups of 7 animals were immunized with two doses of MVvac2 (squares), CE1E2 (circles), or E1/Ft-E2/Ft (triangles). Each symbol represents one animal; a horizontal bar shows the average of the group. Sera were obtained either 4 weeks after the initial infection (4w) or 2 weeks after repeat infection (6w). All sera were assayed for MV neutralization (A; reciprocals of the titer), for reactivity against HCV E2 by ELISA (B; optical density at 450 nm), or for HCV neutralization using an H77-pseudotyped luciferase-expressing retrovirus (C; percent neutralization). In panel B, average readings for the background (−) and monoclonal antibody anti-E2 (+) are shown with gray and black bars, respectively. Even though most of the samples were anti-E2 seropositive as detected by ELISA after the second dose, one and three animals in the MV-CE1E2 and MV-E1/Ft-E2/Ft groups, respectively, had background level values. For panel C, two mice in each experimental group did not develop detectable levels of neutralizing antibodies.