The Central Role of the Matrix Protein in Nipah Virus Assembly and Morphogenesis

Nipah virus (NiV) is an emerging paramyxovirus distinguished by its ability to cause fatal disease in both animal and human hosts. Together with Hendra virus (HeV), they comprise the genus Henipavirus in the Paramyxoviridae family. NiV and HeV are restricted to Biosafety Level-4 (BSL-4) containment and this has hampered progress towards examining the details of their replication and morphogenesis mechanisms. Here, recombinant gene expression systems to study NiV particle assembly and budding through the formation of virus-like particles (VLPs) have been established to circumvent these obstacles. When expressed by recombinant Modified Vaccinia virus Ankara (rMVA) or by plasmid vector transfection, individual NiV matrix (M), fusion (F) and attachment (G) proteins were released into cell culture supernatants in a membrane associated state as determined by sucrose density gradient flotation and immunoprecipitation analysis. However, co-expression of F and G along with M revealed a shift in their distribution across the gradient, indicating association with M in VLPs.