Therapeutic efficacy of bovine ultra-long CDR H3 antibody against BVDV in challenged BALB/c mouse model.

Abstract

Bovine Viral Diarrhea Virus (BVDV), the etiologic agent of bovine viral diarrhea, poses substantial economic threats to the cattle industry worldwide. While vaccination represents the cornerstone of preventive strategies, relying primarily on inactivated whole-virus vaccines, continuous viral evolution has rendered these conventional formulations inadequately protective. Bovine ultralong CDR H3 antibodies, characterized by a 70-amino-acid composition, emerge as promising candidates for therapeutic development. However, their effectiveness against BVDV remains largely unexplored. In this study, a phage display library encoding BVDV-specific ultralong CDR H3 antibodies was successfully constructed and subjected to biopanning. Selected high-affinity antibodies were expressed and purified, and showed specific binding to BVDV with an affinity of 312.5 ng/mL and neutralizing activity (IC&#xa0;=&#xa0;11.72 &#x3bc;g/mL). To evaluate therapeutic efficacy, a BALB/c mouse challenge model was established. We found that antibody treatment significantly reduced viral load and attenuated histopathological damage compared to the control group (<&#xa0;0.05). These results collectively underscore the potential of ultralong CDR H3 antibody platforms as viable candidates for novel BVDV immunotherapeutics and vaccine development.