Funtional and applied studies on the adenovirus minor capsid protein IX

Abstract

The adenoviral vector is one of the most used viral vectors for gene therapy applications. The specificity towards its primary receptor is a limitation of the use of HAdV as therapeutical vector, as not all cells have these primary receptors on their surface. To overcome this problem scientists have started to change the receptor specificity of the HAdV vectors by introducing heterologous polypeptides. One of the most promising candidates to function as anchor for these heterologous polypeptides is the minor capsid protein IX (pIX). Alpha-helical spacers of different lengths have been inserted between pIX and a polypeptide ligand. The results showed that an increase in spacer length positively correlated with the accessibility of the peptide on the capsid surface for antibodies and cellular membrane proteins. Next, a hyper stable scFv directed against __-galactosidase was incorporated in the virion via fusion to pIX. These data were the first to show incorporation of a hyper-stable scFv into the HAdV, and that was functional on the capsid surface. Beside the technical approach to use pIX as anchor for heterologous polypeptides here also the function of pIX in the capsid has been studied. This study has led to the model in which the capsid stability mediated by pIX might not be the result of homo-multimerization of this molecule.