Exploration of New Sites in Adenovirus Hexon for Foreign Peptides Insertion

Abstract

Adenoviral vectors are now being explored as vaccine carriers to prevent infectious diseases in humans and animals. There are two strategies aimed at the expression of a vaccine antigen by adenoviral vectors. The first includes an insertion of the foreign gene expression cassette into the E1 region. The second strategy is antigen incorporation into the viral capsid proteins. To extend this methodology, we have searched for new sites at the human adenovirus serotype 5 major capsid protein hexon for a vaccine antigen insertion. To this end, we utilized sites in the hexon hypervariable region (HVR) 7, 8 and 9 to display a 15-mer peptide containing the main neutralizing epitope of porcine reproductive and respiratory syndrome virus. However, we could not rescue the viruses with the insertions of the peptide into HVR 8 and 9, consistent with the viruses being unable to tolerate insertions at these sites. In contrast, the virus with the insertion of the peptide in HVR 7 was viable - growing well in cell culture and the inserted peptide was exposed on the virion surface.

Capsid-Incorporation Strategy To Display Antigens for an Alternative Adenoviral Vector Vaccine Approach

“…Their study showed that the insertion of the peptide into HVRs 8 and 9 was not tolerated. This is in contrast to the incorporation into HVR7 that resulted in the exposure of the epitope on the virion surface . In conclusion, HVR1–3 and 5–7 tolerate Ag insertion.…”

“…This is in contrast to the incorporation into HVR7 that resulted in the exposure of the epitope on the virion surface. 20 In conclusion, HVR1−3 and 5−7 tolerate Ag insertion.…”

“…These studies also showed that HVR1 accommodates insertions up to 90 aa. ,, The noted study of the incorporation of a neutralizing B-cell epitope from PRRS into HVR7 was the most extensive insertion in HVR7 performed. The epitope size was 9 amino acids (aa) with 3 linker aa on both sides, which makes the total incorporation 15 aa . In conclusion, HVR2 allows incorporation up to 57 aa, HVR5 up to 77 aa, HVR1 up to 90 aa, and HVR7 up to 15 aa.…”

A Novel System for Simple Rapid Adenoviral Vector Construction to Facilitate CRISPR/Cas9-Mediated Genome Editing

“…With this method, it is feasible to modify the adenovirus genome or even chemically synthesize the entire adenovirus genome, enabling the creation of tailored adenoviruses with distinct features. 4,[24][25][26] By replacing the construction of the adenoviral skeleton plasmid vector in the AdEasy system with enzymatic assembly, we ensured that the AdBlue system is rapid. In addition, the kanamycin resistance screening in the AdEasy system is inefficient for screening positive transformants, and at least 10-20 small colonies must be selected for analysis.…”

Novel Genotype Definition and the First Epidemiological Investigation of Canine Adenovirus Type 2 in Dogs in Central China

“…The capsid is icosahedral: and the faces are composed of 240 Hexons, each comprising three identical [Hexon] proteins, and the trimer constitutes the outer sheath of the capsid. Because it contains a specific antigenic determinant, it is also the main protein targeted by the host neutralizing antibody ( 3 ).…”