TABLE 1.

Protein sequence positions embedded in alpha helices, beta sheets, and loops with regard of whether they overlap epitope-presenting or epitope-lacking regions^a

Secondary structure	No. (%) of protein sequence positions embedded in protein regions:
	Epitope lacking	Epitope presenting
Alpha helix	122 (30.1)	283 (69.9)
Beta sheet	123 (50.4)	121 (49.6)
Loop	292 (44.5)	364 (55.5)

^aP < 10⁻⁶ by Fisher's exact test, summary for RT, Gag p24, and p17, Nef, and Env gp120 gp41.