Nipah and Hendra Virus Glycoproteins Induce Comparable Homologous but Distinct Heterologous Fusion Phenotypes

Abstract

Nipah and Hendra viruses (NiV and HeV) exhibit high lethality in humans and are biosafety level 4 (BSL-4) paramyxoviruses in the growing genus Henipavirus. The attachment (G) and fusion (F) envelope glycoproteins are both required for viral entry into cells and for cell-cell fusion, which is pathognomonic of henipaviral infections. Here, we compared the fusogenic capacities between homologous and heterologous pairs of NiV and HeV glycoproteins. Importantly, to accurately measure their fusogenic capacities, as these depend on glycoprotein cell surface expression (CSE) levels, we inserted identical extracellular tags to both fusion (FLAG tags) or both attachment (hemagglutinin [HA] tags) glycoproteins. Importantly, these tags were placed in extracellular sites where they did not affect glycoprotein expression or function. NiV and HeV glycoproteins induced comparable levels of homologous HEK293T cell-cell fusion. Surprisingly, however, while the heterologous NiV F/HeV G (NF/HG) combination yielded a hypofusogenic phenotype, the heterologous HeV F/NiV G (HF/NG) combination yielded a hyperfusogenic phenotype. Pseudotyped viral entry levels primarily corroborated the fusogenic phenotypes of the glycoprotein pairs analyzed. Furthermore, we constructed G and F chimeras that allowed us to map the overall regions in G and F that contributed to these hyperfusogenic or hypofusogenic phenotypes. Importantly, the fusogenic phenotypes of the glycoprotein combinations negatively correlated with the avidities of F-G interactions, supporting the F/G dissociation model of henipavirus-induced membrane fusion, even in the context of heterologous glycoprotein pairs. IMPORTANCE The NiV and HeV henipaviruses are BSL-4 pathogens transmitted from bats. NiV and HeV often lead to human death and animal diseases. The formation of multinucleated cells (syncytia) is a hallmark of henipaviral infections and is caused by fusion of cells coordinated by interactions of the viral attachment (G) and fusion (F) glycoproteins. We found via various assays that viral entry and syncytium formation depend on the viral origin of the glycoproteins, with HeV F and NiV G promoting higher membrane fusion levels than their counterparts. This is important knowledge, since both viruses use the same bat vector species and potential coinfections of these or subsequent hosts may alter the outcome of disease.

Synchronous shedding of multiple bat paramyxoviruses coincides with peak periods of Hendra virus spillover

“…The frequent sample level co-detection of TevPV with all other viruses (highest median interaction coefficients) suggests it may play a central role in driving co-infections, potentially through immunosuppression or perhaps through activation of latent infections, as has been observed in herpesvirus co-infections [58]. Alternatively, a recent study has demonstrated that interactions between glycoproteins in HeV-NiV co-infections may promote viral entry and, perhaps, increase viral loads [59]. Further empirical and modelling studies are warranted to assess whether this approach could contribute to improved spillover predictions.…”

MeV-Stealth: A CD46-specific oncolytic measles virus resistant to neutralization by measles-immune human serum

“…We postulated that the enhanced cell membrane fusion observed for the CDV-H 5804/F SPA pair might be related to a lower binding avidity at the H/F interface. This was based on the observation that H/F dissociation is essential for the fusion process [ 23 , 24 ]. In order to test our hypothesis, we evaluated the relative strengths of association for different combinations of CDV-H and F proteins by coimmunoprecipitation (co-IP) assays.…”

Probing Morbillivirus Antisera Neutralization Using Functional Chimerism between Measles Virus and Canine Distemper Virus Envelope Glycoproteins

“…The strength of envelope protein interaction is known to affect fusion activity [65,66]. Yet, we did not pursue assessment of the H and F physical interaction since our efforts to detect equally the F glycoprotein of the two viral species by means of a FLAG-tag specifically abrogated heterotypic complementation (Muñoz-Alía and Russell, unpublished data, 2019) [67].…”