Targeted N-glycan deletion at the receptor-binding site retains HIV Env NFL trimer integrity and accelerates the elicited antibody response

PLoS Pathogens

Arlette Movsesyan¹  Viktoriya Dubrovskaya¹  Natalia de Val²  Richard T. Wyatt²  Gunilla B. Karlsson Hedestam³  Andrew B. Ward⁴  Javier Guenaga⁴  Yu Feng⁴  Richard Wilson⁴ 

[1] Department of Immunology and Microbiology, The Scripps Research Institute, La Jolla, California, United States of America;Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, California, United States of America;Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Stockholm, Sweden;IAVI Neutralizing Center at TSRI, Department of Research and Development, International AIDS Vaccine Initiative, La Jolla, California, United States of America

关键词: Antibodies;    Antigens;    Rabbits;    Enzyme-linked immunoassays;    B cells;    Antibody response;    Immune response;    Liposomes;   

DOI  :  10.1371/journal.ppat.1006614

学科分类：生物科学（综合）

来源: Public Library of Science

【 摘 要 】

Extensive shielding by N-glycans on the surface of the HIV envelope glycoproteins (Env) restricts B cell recognition of conserved neutralizing determinants. Elicitation of broadly neutralizing antibodies (bNAbs) in selected HIV-infected individuals reveals that Abs capable of penetrating the glycan shield can be generated by the B cell repertoire. Accordingly, we sought to determine if targeted N-glycan deletion might alter antibody responses to Env. We focused on the conserved CD4 binding site (CD4bs) since this is a known neutralizing determinant that is devoid of glycosylation to allow CD4 receptor engagement, but is ringed by surrounding N-glycans. We selectively deleted potential N-glycan sites (PNGS) proximal to the CD4bs on well-ordered clade C 16055 native flexibly linked (NFL) trimers to potentially increase recognition by naïve B cells in vivo. We generated glycan-deleted trimer variants that maintained native-like conformation and stability. Using a panel of CD4bs-directed bNAbs, we demonstrated improved accessibility of the CD4bs on the N-glycan-deleted trimer variants. We showed that pseudoviruses lacking these Env PNGSs were more sensitive to neutralization by CD4bs-specific bNAbs but remained resistant to non-neutralizing mAbs. We performed rabbit immunogenicity experiments using two approaches comparing glycan-deleted to fully glycosylated NFL trimers. The first was to delete 4 PNGS sites and then boost with fully glycosylated Env; the second was to delete 4 sites and gradually re-introduce these N-glycans in subsequent boosts. We demonstrated that the 16055 PNGS-deleted trimers more rapidly elicited serum antibodies that more potently neutralized the CD4bs-proximal-PNGS-deleted viruses in a statistically significant manner and strongly trended towards increased neutralization of fully glycosylated autologous virus. This approach elicited serum IgG capable of cross-neutralizing selected tier 2 viruses lacking N-glycans at residue N276 (natural or engineered), indicating that PNGS deletion of well-ordered trimers is a promising strategy to prime B cell responses to this conserved neutralizing determinant.

【 授权许可】

CC BY