|
Figure 3.
View larger version (42K): [in
this window] [in
a new window] Fig. 3. Immune evasion at the site of initial
CD4 attachment. (A) Recognition similarity. Centers of
recognition for CD4, F105, b12, and b13. After superposition of
gp120 outer domains, the centers of the recognition surface of
each ligand on gp120 is denoted by balls for CD4 (yellow), F105
(blue), b12 (red), and b13 (purple). (B) Immune evasion. The
initial site of CD4 attachment (cross-hatched yellow surface) is
circumscribed by a combination of glycan (green) and
conformational constraints. The surface on gp120 recognized by
F105, b12, and b13 (that strays beyond the site of CD4
attachment) is shown in blue, red, and purple, respectively.
Glycosylation sterically crowds the immune response toward the
bridging-sheet region (blue surface that F105 recognizes) or
toward the V3 region (purple surface that b13 recognizes) (48).
In either case, recognition of these regions of gp120 results in
antibody-bound conformations of gp120 that are poorly compatible
with the functional spikes of HIV-1 virions from tier 2 primary
isolates.
|
