Nipah virus (NiV) is a highly lethal zoonotic paramyxovirus that poses a severe threat to humans due to its high morbidity and the lack of viable countermeasures. Vaccines are the most crucial defense against NiV infections. Here, a recombinant chimpanzee adenovirus-based vaccine (AdC68-G) and a DNA vaccine (DNA-G) were developed by expressing the codon-optimized full-length glycoprotein (G) of NiV. Strong and sustained neutralizing antibody production, accompanied by an effective T-cell response, was induced in BALB/c mice by intranasal or intramuscular administration of one or two doses of AdC68-G, as well as by priming with DNA-G and boosting with intramuscularly administered AdC68-G. Importantly, the neutralizing antibody titers were maintained for up to 68 weeks in the mice that received intramuscularly administered AdC68-G and the prime DNA-G/boost AdC68-G regimen, without a significant decline. Additionally, Syrian golden hamsters immunized with AdC68-G and DNA-G via homologous or heterologous prime/boost immunization were completely protected against a lethal NiV virus challenge, without any apparent weight loss, clinical signs, or pathological tissue damage. There was a significant reduction in but not a complete absence of the viral load and number of infectious particles in the lungs and spleen tissue following NiV challenge. These findings suggest that the AdC68-G and DNA-G vaccines against NiV infection are promising candidates for further development.

Nipah virus (NiV) is a World Health Organization priority pathogen and there are currently no approved drugs for clinical immunotherapy. Through the use of a naïve human phage-displayed Fab library, two neutralizing antibodies (NiV41 and NiV42) targeting the NiV receptor binding protein (RBP) were identified. Following affinity maturation, antibodies derived from NiV41 display cross-reactivity against both NiV and Hendra virus (HeV), whereas the antibody based on NiV42 is only specific to NiV. Results of immunogenetic analysis reveal a correlation between the maturation of antibodies and their antiviral activity. In vivo testing of NiV41 and its mature form (41-6) show protective efficacy against a lethal NiV challenge in hamsters. Furthermore, a 2.88 Å Cryo-EM structure of the tetrameric RBP and antibody complex demonstrates that 41-6 blocks the receptor binding interface. These findings can be beneficial for the development of antiviral drugs and the design of vaccines with broad spectrum against henipaviruses.

Nipah virus (NiV) is a zoonotic emergent paramyxovirus that can cause severe encephalitis and respiratory infections in humans, with a high fatality rate ranging from 40% to 75%. Currently, there are no approved human vaccines or antiviral drugs against NiV. Here, we designed a ferritin-based self-assembling nanoparticle displaying the NiV G head domain on the surface (NiV G-ferritin) and assessed immune responses elicited by the soluble NiV G head domain (NiV sG) or NiV G-ferritin. Immunization with NiV G-ferritin or NiV sG conferred complete protection against lethal NiV challenge without detection of viral RNA in Syrian golden hamsters. Compared to NiV sG, NiV G-ferritin induced significantly faster, broader, and higher serum neutralizing responses against three pathogenic henipaviruses (NiV-Malaysia, NiV-Bangladesh, and Hendra virus). Moreover, NiV G-ferritin induced a durable neutralizing immunity in mice as antisera potently inhibited NiV infection even after six months of the third immunization. Additionally, we isolated a panel of 27 NiV G-binding monoclonal antibodies (mAbs) from NiV G-ferritin immunized mice and found that these mAbs targeted four distinct antigenic sites on NiV G head domain with two sites that have not been defined previously. Notably, 25 isolated mAbs have potent neutralizing activity with 50% inhibitory concentrations less than 10 ng/mL against NiV pseudovirus. Collectively, these findings provide new insights into the immunogenicity of NiV G protein and reveal that NiV G-ferritin is a safe and highly effective vaccine candidate against Nipah virus infection.

Nipah virus (NiV), a bat-borne paramyxovirus, results in neurological and respiratory diseases with high mortality in humans and animals. Developing vaccines is crucial for fighting these diseases. Previously, only a few studies focused on the fusion (F) protein alone as the immunogen. Numerous NiV strains have been identified, including 2 representative strains from Malaysia (NiV-M) and Bangladesh (NiV-B), which differ significantly from each other. In this study, an F protein sequence with the potential to prevent different NiV strain infections was designed by bioinformatics analysis after an in-depth study of NiV sequences in GenBank. Then, a chimpanzee adenoviral vector vaccine and a DNA vaccine were developed. High levels of immune responses were detected after AdC68-F, pVAX1-F, and a prime-boost strategy (pVAX1-F/AdC68-F) in mice. After high titers of humoral responses were induced, the hamsters were challenged by the lethal NiV-M and NiV-B strains separately. The vaccinated hamsters did not show any clinical signs and survived 21 days after infection with either strain of NiV, and no virus was detected in different tissues. These results indicate that the vaccines provided complete protection against representative strains of NiV infection and have the potential to be developed as a broad-spectrum vaccine for human use.

The Hendra and Nipah viruses (HNVs) are highly pathogenic pathogens without approved interventions for human use. In addition, the interaction pattern between the attachment (G) and fusion (F) glycoproteins required for virus entry remains unclear. Here, we isolate a panel of Macaca-derived G-specific antibodies that cross-neutralize HNVs via multiple mechanisms. The most potent antibody, 1E5, confers adequate protection against the Nipah virus challenge in female hamsters. Crystallography demonstrates that 1E5 has a highly similar binding pattern to the receptor. In cryo-electron microscopy studies, the tendency of 1E5 to bind to the upper or lower heads results in two distinct quaternary structures of G. Furthermore, we identify the extended outer loop β1S2-β1S3 of G and two pockets on the apical region of fusion (F) glycoprotein as the essential sites for G-F interactions. This work highlights promising drug candidates against HNVs and contributes deeper insights into the viruses.

Current influenza vaccines provide hemagglutinin strain-specific protection, but rarely provide cross-protection against divergent strains. It is, therefore, particularly important to develop a universal vaccine against conserved proteins or conserved regions of the virus. In this study, we used N-terminal extracellular region of the influenza virus M2 protein (M2e) as the target antigen and constructed two optimized M2e DNA vaccines (p-tPA-p3M2e and p-p3M2e) with increased antigenic epitope density and enhanced antigen secretion. Both vaccines induced high M2e-specific humoral and cellular immune responses in the vaccinated mice. These two vaccines also conferred protection against a lethal infection of homo-subtypic H1N1 virus, with p-tPA-p3M2e being the most effective. In addition, p-tPA-p3M2e also showed cross-protection against different subtypes of the influenza virus (H9N2, H6N6, and H10N8) at varying rates (80%, 40%, and 20%, respectively). After passive immunization, M2e DNA vaccine-induced antibodies in the sera provided complete protection against homologous virus challenge. An analysis of the mechanism underlying this immunization-mediated protection indicates that M2e-specific IgG and T-cell immune responses may play critical roles in the prevention of infection and viral clearance. Taken together, our results indicate that this optimized M2e DNA vaccine is a promising candidate for the development of a universal, broad-spectrum influenza virus vaccine.