Recombinant adenovirus synthesizing cell surface-anchored βhCG induces bioneutralizing antibodies in rats

Abstract

A recombinant adenovirus (re-Ad) has been constructed that synthesizes a cell surface-anchored form of the β-subunit of human chorionic gonadotropin (βhCG). This was achieved by in-frame fusion of βhCG cDNA at its C terminus with the gene sequences coding for the vesicular stomatitis virus glycoprotein (VSVg) transmembrane domain. The fusion protein gene was placed under the control of human cytomegalovirus (hCMV) immediate early promoter and this expression cassette was inserted into the E1 region of Ad type 5 by homologous recombination. In vitro experiments using re-Ad-infected 293 cells showed that βhCG fusion protein was made as early as 6 h post infection and the protein was anchored to the cell membrane as seen by immunofluorescence staining. The re-Ad induced bioneutralizing antibodies (Ab) to hCG when inoculated in rats through intraperitoneal or intramuscular routes. The Ab were made in a dose-dependent manner. However, orally delivered re-Ad failed to generate any significant immune response.