Protection against EHV-1 challenge infection in the murine model after vaccination with various formulations of recombinant glycoprotein gp14 (gB).

Four formulations of the equine herpesvirus type 1 (EHV-1) glycoprotein gp 14 (gB), were tested for their ability to protect mice against intranasal (inas) EHV-1 challenge infection. The preparations tested included (i) a truncated gp14 produced in Escherichia coli or (ii) a truncated gp14 expressed in insect cells by a recombinant baculovirus, (iii) truncated gp14 coexpressed with human immunodeficiency virus type 1 (HIV-1) gag virus-like particles (VLP) in insect cells, and (iv) a gp14-DNA vaccine under the control of the cytomegalovirus immediate early promoter. All antigen preparations and the DNA vaccine elicited a humoral and delayed-type hypersensitivity (DTH) immune response to EHV-1 after intramuscular (im) immunization. After inas immunization, only the VLP-gp14 preparation produced both a good humoral and a prominent DTH immune response; gp14 expressed by insect cells elicited high titers of EHV-1-specific antibodies, whereas gp14 produced in E. coli and the DNA vaccine elicited only low antibody titers. Glycoprotein gp14 expressed by bacteria, however, induced a strong DTH reaction after inas application. Mice were completely protected against EHV-1 challenge infection after both the im and the inas immunization with the VLP-gp14 preparation. Protection was less efficient after immunization with the E. coli and insect cell gp14s as well as after DNA vaccination. Although the transmembrane domain of EHV-1 gp14 was deleted, recombinant gp14 could be demonstrated in insect cell membranes at late times postinfection and aggregated with the VLPs. It is suggested that the transmembrane domain is not required for gp14-association with membranes in that system.