Structural rearrangements maintain the Glycan Shield of an HIV-1 envelope trimer after the loss of a glycan
Date
2018Author
Ferreira, Roux-Cil
Grant, Oliver C.
Moyo, Thandeka
Dorfman, Jeffrey R.
Woods, Robert J.
Travers, Simon A.
Wood, Natasha T.
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Show full item recordAbstract
The HIV-1 envelope (Env) glycoprotein is the primary target of the humoral immune response and a
critical vaccine candidate. However, Env is densely glycosylated and thereby substantially protected
from neutralisation. Importantly, glycan N301 shields V3 loop and CD4 binding site epitopes from
neutralising antibodies. Here, we use molecular dynamics techniques to evaluate the structural
rearrangements that maintain the protective qualities of the glycan shield after the loss of glycan
N301. We examined a naturally occurring subtype C isolate and its N301A mutant; the mutant not
only remained protected against neutralising antibodies targeting underlying epitopes, but also
exhibited an increased resistance to the VRC01 class of broadly neutralising antibodies. Analysis
of this mutant revealed several glycans that were responsible, independently or through synergy,
for the neutralisation resistance of the mutant. These data provide detailed insight into the glycan
shield’s ability to compensate for the loss of a glycan, as well as the cascade of glycan movements on
a protomer, starting at the point mutation, that affects the integrity of an antibody epitope located at
the edge of the diminishing effect. These results present key, previously overlooked, considerations for
HIV-1 Env glycan research and related vaccine studies.