Inducing Antigen‐Specific and Functional Immune Responses in Mice Toward Bovine Herpesvirus 1 and Bovine Respiratory Syncytial Virus by Chimeric Peptides Delivered by Bovine Herpesvirus 4‐Based Vector

Bovine respiratory disease (BRD) remains a major health and economic challenge for the cattle industry, driven by the interplay of viral and bacterial pathogens that compromise animal welfare, productivity and antimicrobial stewardship. Among the primary viral agents, Bovine herpesvirus 1 (BoHV‐1) and Bovine respiratory syncytial virus (BRSV) play critical roles in initiating and exacerbating respiratory pathology. In this study, we engineered two recombinant Bovine herpesvirus 4 (BoHV‐4)‐based vectors encoding chimeric antigens based on BoHV‐1 glycoprotein D (gD) and BRSV fusion glycoprotein (gF), with the goal of developing a multivalent vaccine platform. Immunological evaluation in a murine model demonstrated that both vaccine constructs elicited robust humoral and cell‐mediated immune responses directed against both pathogens. Vaccination induced neutralising antibodies capable of inhibiting BoHV‐1 and BRSV infection, as well as antigen‐specific T‐cell responses that mediated cytotoxic activity against target cells expressing either antigen. These findings provide proof‐of‐concept that chimeric antigens are effective in eliciting humoral and cellular immune response toward two main different pathogens, BoHV‐1 and BRSV, and BoHV‐4 is a versatile vector for the delivery of heterologous antigens. The demonstrated ability to induce both virus neutralisation and cytotoxic T‐cell activity supports the further development of BoHV‐4‐vectored bivalent vaccines for BRD control, with potential application at improving livestock health and reducing reliance on antimicrobial treatments. Moreover, the present study highlights BoHV‐4‐based vectors and chimeric peptides as a promising bivalent vaccine platform potentially translatable for controlling similar viruses like human respiratory syncytial virus (hRSV) and varicella zoster virus (VZV) across human populations.