Enhanced immunogenicity of a BoHV-1 gG-/tk- vaccine.

Bovine herpesvirus type 1 (BoHV-1) is a widespread respiratory infection that significantly impacts cattle health worldwide. To address this issue in China, we previously developed a novel double gene-deleted vaccine targeting gG and tk. In this study, we further evaluated the efficacy of this vaccine by challenging vaccinated cattle with a prevalent wild-type BoHV-1 strain and comparing its effectiveness against a commercially available inactivated BoHV-1 vaccine. Post-immunization, all cattle maintained normal rectal temperatures and exhibited no respiratory symptoms. Cattle receiving the gene-deleted vaccine showed a significant increase in the expression of immune markers IFN-γ and TNF-α. Following exposure to wild-type BoHV-1, all immunized groups produced high levels of neutralizing antibodies and specific gB antibodies. Notably, virus shedding was significantly lower in the vaccinated groups compared to the non-immune challenge group. Histological analysis of lung tissues revealed that vaccinated calves had more intact lung structure than their unimmunized counterparts after the challenge. Additionally, the gG-/tk- gene-deleted vaccine demonstrated a higher protective rate based on the average scores of clinical symptoms and lung lesions. Overall, the BoHV-1 gG-/tk- gene-deleted vaccine outperformed the other vaccines tested. This study confirms that the gene-deleted vaccine provides robust protection and superior immunogenicity compared to existing inactivated vaccines, underscoring its potential for future market application.