Fig. 6: Immunogenicity of BG505 UFO Env immunogens with trimmed glycans in mice and rabbits.
a Schematic representation of mouse and rabbit immunization regimen 1, where glycan-trimmed immunogens were used throughout, and regimen 2, where glycan-trimmed and wildtype immunogens were used as prime (doses 1 and 2) and boost (doses 3 and 4), respectively. A 3-week interval was used to facilitate the rapid evaluation of various vaccine formulations. b Frequency of vaccine responders (FVR) calculated for groups in which mice were immunized with the BG505 UFO trimer (left), E2p SApNP (middle), and I3-01v9 SApNP (right). The first column of each panel represents the all-wildtype regimens as control, with the data either derived from the previous publications (from refs. 27,55, marked with a solid circle) or generated in the current study (Fig. 5b, marked with asterisks). Each experimental repeat (expt. repeat) indicates a different immunization experiment using the same protocol (n = 8 mice/group). Purified mouse IgGs from week 11 were tested against tier 2 clade A BG505.T332N. A vaccine responder is defined as a subject with IC50 ≤300 μg/ml. No IgG was available for one mouse in the UFO trimer/AP regimen 1 group, two mice in the I3-01v9/AP regimen 1 (1st repeat) group, and one mouse each in the wildtype E2p/AP and E2p/AV comparator groups. For each vaccine platform (trimer or SApNP), statistical comparison was made between the wildtype group and the glycan-trimmed group(s) with the highest FVR using a two-sided Fisher’s exact test. c Percent neutralization values of week 11 mouse IgG from select mouse samples (≥ 30% autologous neutralization at the highest IgG concentration) against BG505.T332N and its I396R mutant. d Neutralization of tier 2 clade A BG505.T332N by purified rabbit IgG from week 11 (n = 6 rabbits/group). e FVR of four rabbit groups based on the week 11 autologous neutralization data, with vaccine responders defined as in b. f Percentage neutralization of select week 11 rabbit IgG samples (≥30% autologous neutralization at the highest IgG concentration) against BG505.T332N and its four glycan hole mutants. All mouse and rabbit TZM-bl assays were done in duplicate at a starting concentration of 300 µg/ml, followed by three-fold dilutions. Error bars in the neutralization curves in d represent the difference between the duplicate values for each sample at each concentration tested. Color coding in c and f indicates the level of reduction in % neutralization relative to BG505.T332N. Mouse and rabbit images created with BioRender.com.
