Figure 4.

Circumventing strategies against preexisting vector immunity. (A) Inoculation with a rare human adenoviral (HAdV) or nonhuman AdV can evade the preexisting vector immunity. (B) Since most of the neutralizing antibodies (NAbs) target the capsid proteins, such as the fiber and hexon, exchanging the capsid and/or fiber proteins with a different AdV type can elude the preexisting vector immunity. (C) Chemical encapsulation can mask the AdV vector from antibody-mediated neutralization. (D) The use of different routes of inoculation or different vector platforms (prime–boost approach) can circumvent the preexisting vector immunity. ChAdV, chimpanzee adenovirus; PEG, polyethylene glycol.