Summary auto-generated
This study describes the successful expression of infectious bronchitis virus (IBV) spike protein using recombinant vaccinia virus as a vector. Researchers cloned the IBV spike gene into vaccinia virus to create recombinant virus vSP19-1. When cells infected with this recombinant virus were analyzed, they produced the 180-kilodalton spike protein precursor in properly glycosylated form and transported it to the cell surface, as demonstrated by immunofluorescence and immunoprecipitation. Notably, the spike protein was not cleaved into its S1 and S2 subunits, yet remained immunologically functional. Mice vaccinated with the recombinant virus developed antibodies against IBV spike antigen detectable by ELISA and produced neutralizing antibodies capable of inhibiting IBV infectivity, as shown by ciliostasis assays in chicken tracheal organ cultures. The neutralizing antibodies generated against the Beaudette strain spike protein even cross-neutralized the more virulent M41 IBV strain. These findings suggest that recombinant vaccinia virus expressing IBV spike protein could potentially serve as a live vaccine candidate for infectious bronchitis in poultry.
Key findings
- Recombinant vaccinia virus successfully expressed the IBV spike protein as a properly glycosylated 180K molecular weight precursor on infected cell surfaces
- The spike protein was transported to the cell membrane and recognized by antibodies despite lacking proteolytic cleavage into S1 and S2 subunits
- Vaccinated mice produced virus-neutralizing antibodies that inhibited IBV infectivity in tracheal organ culture assays, with cross-neutralization activity against heterologous IBV strains
- Spike protein expression did not require other IBV proteins, demonstrating that proper membrane transport and immunogenicity depend on intrinsic properties of the spike protein itself
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Abstract
A cDNA clone of the infectious bronchitis virus (IBV) spike protein gene has been recombined into vaccinia virus. Cells infected with the recombinant virus synthesized IBV spike antigen which was recognized by antibody raised against purified spike protein. Immunofluorescence showed that the IBV spike antigen was transported to the infected cell surface membrane and immunoprecipitation showed the presence of the glycosylated 180K mol. wt. polypeptide precursor of the two spike subunits S1 and S2 that comigrated with this antigen from IBV-infected cells. Vaccinated mice produced antibody that recognized the IBV spike antigen by ELISA and which neutralized IBV infectivity as shown by ciliostasis tests on tracheal organ cultures.