Construction and insect larval expression of recombinant vesicular stomatitis nucleocapsid protein and its use in competitive ELISA.

The gene encoding the nucleocapsid (N) protein of Indiana 1 serotype vesicular stomatitis virus (VSV-IN1) was transferred into the genome of Autographa californica nuclear polyhedrosis virus (baculovirus) as a full-length non-fusion construct under the control of the polyhedrin gene promoter. Recombinant N protein was obtained from Trichoplusia ni insect larvae inoculated 72-96 h previously with the recombinant baculovirus. Polyclonal antibody (PAB) against VSV-IN1 was produced in mice using VSV-IN1 whole virus antigen concentrated from virus-infected cell culture fluids. The N protein and the PAB were used without further purification in a competitive enzyme-linked immunosorbent assay (C-ELISA) for detection of bovine, porcine, and equine origin serum antibodies against VSV-IN1. A limited number of field origin, experimental, and reference VSV antisera were evaluated using the C-ELISA and with a standard serum neutralization (SN) procedure. Sensitivity of the C-ELISA was comparable to the serotypically homologous SN procedure. Subject to further validation, similar C-ELISA tests for the other VSV serotypes, used in conjunction with the test described here, may offer the best combination of rapidity, sensitivity, simplicity, economy, and laboratory biosafety of any of the methods yet developed for VSV serodiagnosis.