Figure 2. Schematics of bivalent RNA aptamers used as agonists.
A) The bivalent 4-1BB aptamer. The 3′-terminus of two 4-1BB aptamers are attached to a 21-nt complementary linker sequence and subsequently annealed together. B) The bivalent OX40 aptamer. The 3′-end linker sequences (20 nt in length) of OX40 aptamers were annealed to a flexible DNA scaffold. A tandem repeat of 20 nt DNA oligos was connected by a flexible polyethylene spacer.