EXPRESSION OF BOVINE INTERLEUKIN-1-BETA IN A BOVINE HERPESVIRUS-1 VECTOR - IN-VITRO ANALYSIS

In order to evaluate whether bovine herpesvirus-1 (BHV-1) could be use d as a live viral vector for the expression of cytokines, we construct ed a recombinant BHV-1 expressing bovine interleukin-1 beta (bolL-1 be ta). The bolL-1 beta coding sequence, corresponding to the cleaved mat ure product, was fused with the BHV-1 glycoprotein C (gC) signal pepti de sequence; the resultant gC-boIL-1 beta fusion gene was recombined i nto the gC locus of the BHV-1 genome, Southern blot analysis confirmed the proper genomic configuration of the recombinant virus. Results fr om transcript analysis showed that boIL-1 beta was expressed in infect ed cells with kinetics similar to that of go. Indirect immunofluoresce nce and immunoprecipitation assays showed that the recombinant protein was produced in both cell-associated and secreted forms. Western blot analysis detected a 19.3-kDa protein. Further analysis, using an IL-1 beta bioassay demonstrated that both the cellular and secreted forms of recombinant boIL-1 beta possessed biological activity. The expressi on of the boIL-1 beta protein did not affect the in vitro growth effic iency of the virus, which exhibited similar growth kinetics to that of a simple gC deletion mutant. The results from this study demonstrate that BHV-1 can be used to express a functional cytokine, thereby estab lishing the basis to further study recombinant BHV-1 expressing cytoki nes as an alternative means to attenuate the virus and also as a poten tial in situ cytokine delivery system to modulate immune responses aga inst BHV-1 and other cattle pathogens. (C) 1996 Academic Press, Inc.