Vaccinia virus strain Western Reserve protein B14 is an intracellular virulence factor
Chen RA-J., Jacobs N., Smith GL.
A characterization of theB14Rgene fromVaccinia virus(VACV) strain Western Reserve (WR) is presented. Computational analyses of theB14Rgene indicated high conservation in orthopoxviruses but no orthologues outside thePoxviridae. To characterize the B14 protein, theB14Rgene was expressed inEscherichia coliand recombinant protein was purified and used to generate a rabbit polyclonal antiserum. This antiserum recognized a 15 kDa cytoplasmic protein in mammalian cells that were transfected with theB14Rgene or infected with VACV WR, but not from cells infected with a VACV mutant (vΔB14) from which theB14Rgene was deleted. Compared to wild-type and revertant virus controls, vΔB14 had normal growth kinetics in cell culture. The virulence of vΔB14 was assessed in twoin vivomodels. Mice infected intranasally with vΔB14 had similar weight loss compared to the controls, but in C57BL/6 mice infected intradermally vΔB14 induced a smaller lesion size compared with controls. Moreover, intradermal infection with vΔB14 caused an increased infiltration of cells into the infected lesion despite the smaller lesion size. Therefore, B14 is an intracellular protein that is non-essential for virus replication in cell culture but contributes to virus virulencein vivoand affects the host response to infection.