Generation, characterization, and application of caprine herpesvirus 1 secreted glycoprotein D

Caprine herpesvirus 1 (CpHV-1), a member of the <i>Herpesvirales</i> order, <i>Herpesviridae</i> family, <i>Alphaherpesvirinae</i> subfamily, and <i>Simplexvirus</i> genus, is classically associated with two distinct clinical syndromes. In kids, CpHV-1 induces severe systemic disease with high morbidity and mortality, whereas in adult goats, the infection leads to genital lesions such as vulvovaginitis or balanoposthitis, with abortions occurring mainly in the second half of gestation. CpHV-1 shares several biological characteristics with human herpesvirus 2, including molecular features, tropism for vaginal epithelium, genital lesion nature, and latency in the sacral ganglia. These features make CpHV-1-infected goats a reliable animal model for studying human herpesvirus-induced genital disease, relevant for pathogenic research, as well as the development of new vaccines and antiviral agents. Recent full sequencing of the CpHV-1 genome has identified at least 10 genes encoding glycoproteins. Among these, glycoprotein D (gD) has been characterized but not yet exploited for immunogenic or diagnostic purposes. In this study, the structural features of CpHV-1 gD were predicted using <i>in silico</i> analysis. A truncated version of gD lacking the transmembrane domain (secreted glycoprotein D [Sec-gD]) was subsequently generated and expressed in mammalian cells, enabling its secretion into the culture medium. Despite the structural modifications, Sec-gD retained a conserved glycosylation pattern, as confirmed by N-glycosylation mutants generation and peptide-N-glycosidase F treatment. Furthermore, the antigenic properties of Sec-gD were preserved, as demonstrated by reverse serum neutralization assays. Notably, the culture supernatant containing Sec-gD was directly usable in diagnostic enzyme-linked immunosorbent assays, supporting its potential as a valuable tool for both diagnostic and immunization strategies.IMPORTANCECaprine herpesvirus 1 (CpHV-1)-infected goats represent a large animal model for studying human herpesvirus-induced genital disease and could be utilized for pathogenic research, as well as for the development of new vaccines and antiviral agents. CpHV-1 glycoprotein D can be efficiently produced and rescued from the supernatant of transfected mammalian cells, retaining its immunogenic properties, and could be used for immunogenic and diagnostic purposes.