Bovine herpesvirus glycoprotein D: a review of its structural characteristics and applications in vaccinology

The viral envelope glycoprotein D from bovine herpesviruses 1 and 5 (BoHV-1 and -5), two important pathogens of cattle, is a major component of the virion and plays a critical role in the pathogenesis of herpesviruses. Glycoprotein D is essential for virus penetration into permissive cells and thus is a major target for virus neutralizing antibodies during infection. In view of its role in the induction of protective immunity, gD has been tested in new vaccine development strategies against both viruses. Subunit, DNA and vectored vaccine candidates have been developed using this glycoprotein as the primary antigen, demonstrating that gD has the capacity to induce robust virus neutralizing antibodies and strong cell-mediated immune responses, as well as protection from clinical symptoms, in target species. This review highlights the structural and functional characteristics of BoHV-1, BoHV-5 and where appropriate, Human herpesvirus gD, as well as its role in viral entry and interactions with host cell receptors. Furthermore, the interactions of gD with the host immune system are discussed. Finally, the application of this glycoprotein in new vaccine design is reviewed, taking its structural and functional characteristics into consideration.