Soluble prefusion-closed HIV-envelope trimers with glycan-covered bases
Adam S. Olia, Cheng Cheng, Tongqing Zhou, Andrea Biju, Darcy R. Harris, Anita Changela, Hongying Duan, Vera B. Ivleva, Wing‐Pui Kong, Li Ou, Reda Rawi, Yaroslav Tsybovsky, David J. Van Wazer, Angela R. Corrigan, Christopher A. Gonelli, Myungjin Lee, Krisha McKee, Sandeep Narpala, Sijy O’Dell, Danealle K. Parchment, Erik-Stephane D. Stancofski, Tyler Stephens, Ivy Tan, I‐Ting Teng, Shuishu Wang, Qing Wei, Yongping Yang, Zhengrong Yang, Baoshan Zhang, Jan Novák, Matthew B. Renfrow, Nicole A. Doria-Rose, Richard A. Koup, Adrian B. McDermott, Jason G. Gall, Q. Paula Lei, John R. Mascola, Peter D. Kwong
Abstract
Soluble HIV-1-envelope (Env) trimers elicit immune responses that target their solvent-exposed protein bases, the result of removing these trimers from their native membrane-bound context. To assess whether glycosylation could limit these base responses, we introduced sequons encoding potential N -linked glycosylation sites (PNGSs) into base-proximal regions. Expression and antigenic analyses indicated trimers bearing six-introduced PNGSs to have reduced base recognition. Cryo-EM analysis revealed trimers with introduced PNGSs to be prone to disassembly and introduced PNGS to be disordered. Protein-base and glycan-base trimers induced reciprocally symmetric ELISA responses, in which only a small fraction of the antibody response to glycan-base trimers recognized protein-base trimers and vice versa. EM polyclonal epitope mapping revealed glycan-base trimers –even those that were stable biochemically– to elicit antibodies that recognized disassembled trimers. Introduced glycans can thus mask the protein base but their introduction may yield neo-epitopes that dominate the immune response.