Figure 7.

Boosting Chimpanzee SIV MT145K Trimer-Induced B Cell Responses with an HIV Trimer Cocktail in CH01 UCA HC-Only Knockin Mice

(A) Schematic showing immunization schedule of CH01 UCA HC-only KI mice with a chimpanzee SIV MT145K trimer followed by an HIV Env-derived three-trimer cocktail. A group of five animals was immunized with two doses (prime, week 0; boost-1, week 4) of the MT145K trimer (as also shown in Figure 6). The animals were further boosted (boost-2 at week 8) with an HIV Env-derived three-trimer cocktail (C108, WITO, and ZM197-ZM233V1V2). The V1V2 loops on trimer cartoons are depicted in red to highlight that the region is shared between HIV and SIV Env trimers. The CH01 UCA HC-only KI mice were immunized with 25 μg of the soluble MT145K trimer or HIV three-trimer cocktail (25 μg total) with GLA-SE as adjuvant. Time points for the immunizations and the bleeds are indicated.

(B) The ID50 virus neutralization titers of the Bleed #4 serum samples collected post boost-2 immunization with an HIV three-trimer cocktail. The neutralization of the post-immune sera was assessed against the priming immunogen-matched autologous virus, MT145K, the boosting immunogen-matched, CH01 sensitive viruses, and global panel HIV Env-encoding viruses. Each filled circle in the plot represents virus ID50 neutralization values for the individual animals; an asterisk (^∗) indicates that 50% neutralization was not reached at a 1:100 serum dilution.