Characteristics of neutralizing antibodies to adenovirus capsid proteins in human and animal sera

Although it is known that Ad5-specific neutralizing antibodies (NAbs) against three major viral capsid components (hexon, penton and fiber) are generated, differences in the frequency and nature of these pre-existing NAbs remain unclear. The results emphasized the contribution of anti-fiber antibodies to Ad5 neutralization responses generated during natural viral infection. Additionally, Ad5-specific NAbs against the fiber knob protein were present in over 90% of the positive serum samples while 42% of the sera had NAbs against hexon in this study based on neutralization assay of anti-HVR and anti-knob subtracted sera and Western blotting analysis. We also found that the trimeric knob was preferentially recognized by fiber-induced NAbs and it was serotype-specific in human adenovirus species C. Results indicated that the trimeric knob protein would be a good candidate antigen for detecting adenovirus serotype-specific NAbs in naturally infected sera.

► NAbs against fiber are commonly generated in natural adenovirus infection in humans.
► Trimeric knob protein was specifically recognized by Ad NAbs in species C.
► Trimeric knob protein would be a good candidate antigen for detecting Ad serotype-specific NAbs.