Table 1.

Nomenclature and description of HIV-1 gp120 outer domain fragment constructs based on HXBc2 strain

No.	Construct name	Description
1	ODEC	HIV-1 gp120 outer domain (OD) fragment from HXBc2 strain was codon-optimized for expression in E. coli with all 14 PNGS intact. This fragment consists of residues 255–474 of gp120 with 11 designed mutations to prevent aggregation. It lacks V1/V2 and V3 variable loops but retains V4 loop residues (66)
2	ΔG14-ODECa	An ODEC variant lacking all 14 PNGS
3	ODYCO	The same amino acid sequence as ODEC but codon-optimized for expression in yeast (S. cerevisiae). All 14 PNGS are intact. YCO stands for yeast codon-optimized
4	ΔG4-ODYCO	Partially glycan-free ODYCO lacking four PNGS (at residues 276, 386, 392, and 463) proximal to the CD4-binding region
5	ΔG14-ODYCO	Completely glycan-free derivative of ODYCO. Devoid of all 14 outer domain PNGS
6	ΔG14-ODYCO-D368R	ΔG14-ODYCO with a D368R mutation known to decrease the binding of gp120 with CD4-binding site antibodies

^a ΔG in a construct's name indicates that it lacks certain glycosylation sites, whereas the numeral followed by ΔG indicates the total number of glycosylation sites mutated. The background in which each construct is made is also indicated in the construct's name. This scheme of nomenclature is followed throughout the paper.