The Chimpanzee SIV Envelope Trimer: Structure and Deployment as an HIV Vaccine Template

Andrabi, Raiees; Pallesen, Jesper; Allen, Joel D.; Song, Ge; Zhang, Jinsong; de Val, Natalia; Gegg, Gavin; Porter, Katelyn; Su, Ching-Yao; Pauthner, Matthias; Newman, Amanda; Bouton-Verville, Hilary; Garces, Fernando; Wilson, Ian A.; Crispin, Max; Hahn, Beatrice H.; Haynes, Barton F.; Verkoczy, Laurent; Ward, Andrew B.; Burton, Dennis R.

Next, we evaluated immune sera for neutralization of autologous and heterologous viruses. Reproducible MT145K autologous virus-specific neutralizing Ab responses were induced in the MT145K immunization group but not in the MT145-WT immunization group (Figures 6C and 6D) . As for the ELISA binding responses, the nAb titers in the MT145K trimer immunized group increased at 2 weeks post prime, as indicated by nAb titers against a highly CH01-sensitive HIV Env-encoding virus (Q23_17) and, further, markedly increased after the boost-1 immunization ( Figure 6C ). At this point, all animals in the MT145K group developed autologous virus-specific nAb responses (Figure 6C ). The nAb responses in MT145K trimer-immunized animals mapped to the glycan N160 and strand C K171 residue, both of which form part of the core epitope for V2-apex bnAbs, suggesting that the MT145K trimer successfully primed V2-apex UCA B cells in an epitope-specific manner in vivo.