Receptor Binding Domain Based HIV Vaccines
(a) Primary structure of HIV-1 Eve glycoprotein and sequence variations in different regions of the Eve. Approximate locations conserved regions (C1 to C5) and variable regions (V1 to V5) are shown along with the numbering scheme of amino acids. The cross-linking disulfide bonds connecting various segments. SP: surfactant protein; FP: fusion peptide; HR: heptad repeat; TM: transmembrane domain; CP: cytoplasm domain. (b) Crystal structures  of gp120. The inner domain in the left portion of core gp120, the outer domain in the right portion, and the 4-stranded sheet at the bottom left of gp120 as the bridging sheet (β3, β2, β21, and β20). α-Helices are depicted in red and β-strands in salmon, except for strand β15 (yellow), which makes an antiparallel β-sheet alignment with strand C terminal of CD4. Connections are shown in grey, except for the disordered V4 loop (dashed line) connecting β18 and β19.
|(a) HIV-1 Env gp120/gp41|
|(b) Structure of gp120|