Monoclonal antibody against canine distemper virus H protein potently neutralizes the giant panda-derived strain

Canine distemper virus (CDV) is a multi-host pathogen with high morbidity and mortality, posing a severe threat to endangered carnivores, including giant pandas. Current vaccines carry risks of vaccine-induced disease in non-target species, creating an urgent need for safe and effective therapeutic alternatives. The hemagglutinin (H) protein is the primary antigen for stimulating neutralizing antibodies. In this study, we generated three murine monoclonal antibodies (mAbs)—2D1, 6G4, and 6H4—using the H protein from a giant panda-derived CDV strain expressed in a mammalian system to preserve authentic glycosylation and conformation. All three mAbs exhibited potent neutralizing activity against the giant panda-derived CDV strain in vitro. Western blot analysis revealed distinct epitope specificities: mAb 2D1 recognized a continuous epitope, as it bound to both eukaryotic and prokaryotically expressed H protein, whereas mAbs 6G4 and 6H4 only reacted with the eukaryotic-expressed protein, suggesting their recognition of non-continuous, conformational epitopes. These data indicate that these mAbs represent promising immunotherapeutic candidates for the control of CDV in giant pandas and other susceptible wildlife.