Development of a neutralization ccombody, synthetic hagfish antibody, for viral hemorrhagic septicemia virus (VHSV) targeting glycoprotein G.

Viral hemorrhagic septicemia virus (VHSV) is a highly contagious fish pathogen affecting a wide range of marine and freshwater fish species worldwide. Its geographic distribution is predicted to expand, increasing the probability of transmission to previously unexposed host species. In the absence of effective control strategies for VHSV, the development of large-scale therapeutic interventions remains a priority for fish farmers to control disease outbreaks. A key target for vaccines and virus-neutralizing agents is the surface glycoprotein G, which plays a crucial role in viral entry and host specificity. In this study, we identified a synthetic, consensus-designed ccombody, based on the hagfish variable lymphocyte receptor B (VLRB), capable of binding VHSV. Two candidates, V4B and V4H, were selected, expressed in bacteria, and purified. Binding affinity to VHSV was confirmed through ELISA and Western blotting, while a pull-down assay followed by mass spectrometric analysis demonstrated recognition of the viral G protein. Immunofluorescence assays revealed that both ccombodies recognized the VHSV G protein in its native conformation within infected cells, indicating their potential for use in imaging and diagnostic applications. Neutralization assays revealed that V4B attenuated cytopathic effects in VHSV-infected cell cultures, supporting its potential application in future intervention strategies.