Development of a novel hybrid alphavirus-Nipah virus pseudovirion for rapid quantification of vaccine-induced neutralization antibodies.

Nipah virus (NiV) is an emergent paramyxovirus that causes serious disease in humans and animals. Accurate quantification of neutralizing antibodies (nAB) against NiV is essential for vaccine development. The current standard, the plaque reduction neutralization test (PRNT), requires authentic infectious NiV and BSL-4 containment, taking 4-7 days to complete. In this study, we developed a hybrid alphavirus-Nipah virus pseudovirion (Ha-NiV) composed of a non-replicating Nipah virus virus-like particle (VLP) that encapsulates an RNA genome from a fast-expressing SFV (Semliki Forest Virus) alphaviral vector. Ha-NiV can infect NiV target cells but is replication incompetent, enabling rapid quantification of nAB (6-18 h) in BSL-2 conditions. We demonstrated concentration-dependent neutralization of Ha-NiV using an anti-NiV F glycoprotein antibody, 12B2, which is induced with a prefusion stabilized NiV F ectodomain trimer. We further validated the Ha-NiV-based neutralization assay using sera from Nipah virus-infected African green monkeys, and established a good correlation (R² = 0.86) with PRNT, demonstrating comparable specificity and sensitivity. These results demonstrate that the Ha-NiV assay can serve as a novel platform for convenient and rapid quantification of vaccine-induced nAB in BSL-2 settings.