This morning, I found 4 scientific papers, on the vaccines made using an adenovirus vector, developed against MERS, a coronavirus similar to SARS-CoV-2. All were published by Sarah Gilbert, among others.
The first paper describes the adenovirus vector itself, which became their standard DNA vaccine vector. The other 3 papers clearly say that the vaccine's adenovirus vector contained DNA coding for the full spike (S) protein from the MERS virus. I could not find a paper describing the SARS-CoV-2 vaccine in detail, but I think it's safe to assume their methods followed those published for the MERS virus. They put the DNA sequence for the SARS-CoV-2 virus S protein into their adenovirus vector, as they previously had done with the MERS S protein.
If I quote text below, it appeared in the introduction sections of these papers.
PLOS One 2012
This paper describes and characterizes the Oxford Group's original adenovirus vector.
Vaccine, 2017
The Middle East respiratory syndrome coronavirus (MERS-CoV) has infected more than 1900 humans, since 2012. The syndrome ranges from asymptomatic and …
reader.elsevier.com
"Here, we report development of MERS-CoV vaccine candidates that are based on two different viralvectors: Chimpanzee Adenovirus, Oxford University #1 (ChAdOx1) and Modified Vaccinia virus Ankara (MVA). Each viral vector was developed by generating two alternative versions, resulting in four vaccine candidates that all encode the same complete MERS-CoV spike gene (S)."
Nature, 2019
"The trimeric spike (S) glycoprotein is the main target of most experimental MERS-CoV vaccines as it plays an integral role in viral entry and fusion with target cells. It consists of a receptor-binding domain (RBD)-containing S1 subunit that binds to dipeptidyl peptidase 4 (DPP4) on target cells, and a S2 subunit which contains the fusion peptide involved in viral fusion with target cells. Several vaccine candidates have been developed and tested in multiple animal models including mice, rabbits, non-human primates and dromedaries (reviewed in 22–24). While many of these vaccines were designed based on full-length S protein, some others were targeting the S1 subunit or the RBD of the protein to focus the immune response on the critical neutralising epitopes to induce nAbs. Nonetheless, non-neutralising antibodies (Abs) could also aid in protection against MERS-CoV by inhibiting essential steps in viral replication such as virus-target cell fusion. Furthermore, it has been shown that nAbs alone could not confer sterilising immunity but could provide partial protection in camels probably due to several factors including waning of nAbs and genetic change of viral lineage. Thus, developing a camel vaccine based on full-length S protein could potentially elicit more robust antibody and T cell response compared to shorter targets. We have developed a chimpanzee adenoviral vector based vaccine for MERS-CoV (ChAdOx1 MERS) that has now been tested in mouse models for immunogenicity and efficacy, demonstrating 100% efficacy after a single dose. ChAdOx1 MERS was generated by inserting the full length of the spike gene, from a MERS-CoV isolate (Genbank accession number: KJ650098.1), into the genome of the replication deficient ChAdOx1 vector as described previously."
Science, 2020
"We recently demonstrated that vaccination of mice with a replication-deficient simian adenovirus vaccine vector (ChA-dOx1) encoding full-length MERS-CoV S protein (ChAdOx1 MERS) elicited high-titer MERS-CoV neutralizing antibodies and a robust CD8+ T cell response against the S protein."
