Figure 1.

Anti-Env Ab responses in vaccinated RMs before and after virus challenge. A. Time line of vaccine/challenge study [12]. In red, immunization phase; in blue, challenge phase. Plasma samples were collected at weeks −1, 0, 1, 2 and 6. B. Quantitative ELISA to determine Env-specific Ab titers in two vaccine-protected RMs. In red, time points post 3^rd immunization and pre-challenge; in blue, time points post challenge. C. Time line of immunogenicity study (unpublished). The last protein immunization was designated as week −2, so that the subsequent weeks would correspond to the study in (A). D. Quantitative ELISA to determine Env-specific Ab titers in eight vaccinated, but not challenged RMs. In red, 1 or 2 weeks post 3^rd immunization; in green, subsequent time points. E. The gp140_CN54-specific Ab titers were compared before and after live-virus challenges in five completely protected vaccinees. The challenge viruses used are indicated. Height of each bar, average titer from three independent assays; error bars, standard error of the mean (SEM). P values are shown (P < 0.05 was considered significant). F. Subtractive biopanning. Three rounds of selection were performed to identify Ab epitopes linked to live-virus exposure. Each round of selection consists of (1) positive selection, (2) negative selection and (3) amplification of the selected phages. Light gray, the Fc portion of all Abs. Dark gray, Fab portion of anti-RM IgG immobilized onto paramagnetic beads via the Fc. Positive selection used week 7 plasma from a protected animal. In dark blue, Fab portions of the live-virus induced Abs and the corresponding phages. Positively selected recombinant phages were counter-selected with plasma from the same vaccinee but collected at week 0 (containing vaccine-induced Abs only). In red, Fab portions of negative selector Abs and the corresponding bound phages. Purple or yellow phages, unspecific phages bound to anti-RM Ab or beads, respectively.