Comparison of protection levels against pseudorabies virus infection of transgenic mice expressing a soluble form of porcine nectin-1/HveC and vaccinated mice

We recently generated transgenic mice expressing a soluble form of porcine nectin-1 (PHveCIg) showing remarkable resistance to pseudorabies virus (PRV) infection. Nectin-1, also known as herpesvirus entry mediator C (HveC), is an alphaherpesvirus receptor that binds to virion glycoprotein D (gD). In order to evaluate the level of resistance to PRV infection induced by the expression of PHveCIg in the transgenic mice, the protective effects of vaccinated and transgenic mice were directly compared. Mice were immunized with a live vaccine, through intraperitoneal injection of PRV strain Begonia (an attenuated vaccine strain deleted for gE and thymidine kinase genes) at 4 weeks before challenge. The vaccinated and transgenic mice were challenged with 10LD₅₀, 20LD₅₀ or 50LD₅₀ of PRV strainYS-81 via intranasal route. In the vaccinated mice, no protection was observed in the challenges with 20LD₅₀ and 50LD₅₀. Only two out of six vaccinated mice survived in the challenge with 10LD₅₀. In contrast, four transgenic mouse lines showed significant resistance to PRV infection, although the survival rates varied in the challenge with each viral dose. These results demonstrate clearly the high potential of transgenic strategy in control of pseudorabies.