Nipah virus (NiV) and Hendra virus (HeV) have an extremely high case fatality, leading to hundreds of deaths in several countries around the globe. Belonging to the same genus Henipavirus (HNV), the two species have a high degree of sequence similarity, resulting in cross-neutralizing immunity under favorable conditions. Here, we obtained ten anti-NiV-F monoclonal antibodies using hybridoma technology, and verified that these antibodies had potent neutralizing activities against epidemic NiV strains from different regions using a pseudovirus assay, and the neutralizing concentration reached the nanogram per milliliter level. Moreover, two of the antibodies, NiF03-3C9 and NiF03-2F6, were found to have cross-neutralizing activity against HeV, which was even stronger than that against NiV. Epitope competition analysis revealed two classes of epitopes for these antibodies. Cryo-electron microscopy showed that NiF03-3C9 binds to lateral residues of the prefusion F protein trimer, highly conserved in both Nipah and Hendra. The protective potency of the antibodies was also validated using in vivo pseudovirus infection models of Nipah and Hendra viruses. The mAbs developed in this study and their conserved cross-neutralizing epitopes elucidated by structural analysis may contribute to the control of highly pathogenic HNV outbreaks.

Neutralizing antibodies targeting the spike (S) protein of SARS-CoV-2, elicited either by natural infection or vaccination, are crucial for protection against the virus. Nonetheless, the emergence of viral escape mutants presents ongoing challenges by contributing to breakthrough infections. To define the evolution trajectory of SARS-CoV-2 within the immune population, we co-incubated replication-competent rVSV/SARS-CoV-2/GFP chimeric viruses with sera from COVID-19 convalescents. Our findings revealed that the E484D mutation contributes to increased viral resistant against both convalescent and vaccinated sera, while the L1265R/H1271Y double mutation enhanced viral infectivity in 293T-hACE2 and Vero cells. These findings suggest that under the selective pressure of polyclonal antibodies, SARS-CoV-2 has the potential to accumulate mutations that facilitate either immune evasion or greater infectivity, facilitating its adaption to neutralizing antibody responses. Although the mutations identified in this study currently exhibit low prevalence in the circulating SARS-CoV-2 populations, the continuous and meticulous surveillance of viral mutations remains crucial. Moreover, there is an urgent necessity to develop next-generation antibody therapeutics and vaccines that target diverse, less mutation-prone antigenic sites to ensure more comprehensive and durable immune protection against SARS-CoV-2.

Objective: Establish an in vivo evaluation model focused on the attachment and entry stages of Hendra virus infection for protective immunity assessment. Methods: A golden hamster infection model based on recombinant Hendra-F/G pseudovirus was developed, and a luciferase luminescence assay was used to assess the optimal pseudoviral challenge in terms of route of infection, dose and detection time. The biodistribution of the pseudovirus in infected organs was evaluated using the IVIS spectral CT system. The protective effect of antibody prophylaxis was evaluated by measuring the luminescence intensity of pseudoviruses. Results: Intraperitoneal injection was identified as the optimal route of infection, and the optimal time of detection was 6 h post-challenge. Our model simulates the infection of the brain and lungs by live viruses, with the strongest infection occurring in the abdomen, especially in the intestinal organs. The dose of pseudovirus was linearly correlated with luminescence intensity. The infection model was able to differentiate the protective effect of monoclonal antibodies, with complete protection in the high-dose group. Conclusions: The recombinant Hendra-F/G pseudovirus hamster model allows the effective evaluation of prophylactic monoclonal antibodies, providing a crucial tool for studying Hendra virus infection and control strategies.