Chimpanzee adenovirus type 3 vector capsid (ChAd3)

The Chimpanzee adenovirus type 3 (ChAd3) vector capsid is a non-enveloped, icosahedral protein structure that serves as a delivery system for genetic material in vaccine development. It is derived from a simian adenovirus to circumvent the high levels of pre-existing neutralizing antibodies found in humans against common human adenoviruses like Ad5 (Stanley et al., 2014, Nature Medicine). The capsid is primarily composed of three major proteins: the hexon, the penton base, and the fiber, which collectively determine the vector's tropism and immunogenicity (Colloca et al., 2012, Science Translational Medicine). In therapeutic use, the ChAd3 vector is typically rendered replication-deficient by deleting the E1 gene region and is used to express foreign antigens, such as the Ebola virus glycoprotein or Hepatitis C virus non-structural proteins (Ledgerwood et al., 2017, New England Journal of Medicine). The capsid's primary role is to protect the DNA payload and facilitate its transport into the nucleus of host cells, where the antigen is produced to stimulate a robust immune response. While generally well-tolerated, the use of ChAd3 capsids requires monitoring for anti-vector immunity, which can limit the efficacy of repeated doses (Barnes et al., 2012, Science Translational Medicine).

Other names

Chimpanzee adenovirus 3cAd3ChAd3 vectorChimpanzee adenovirus serotype 3

The ChAd3 vector capsid facilitates the delivery of genetic material into host cells by binding to cellular receptors and undergoing endocytosis. Once inside, the capsid protects the viral genome during transport to the nucleus, where the encoded therapeutic antigen is expressed to elicit a robust T-cell and B-cell immune response.