Newcastle disease virus fusion and haemagglutinin-neuraminidase proteins contribute to its macrophage host range.

The fusion (F) and haemagglutinin-neuraminidase (HN) proteins of Newcastle disease virus (NDV) are multifunctional proteins that play critical roles during infection. Here, we assessed the ability of NDV to replicate in macrophages and investigated the contribution of the F and HN proteins to NDV infection/replication in these cells. Results of our study revealed that, while presenting similar replication kinetics in a fibroblast cell line (DF1) or in primary non-adherent splenocytes, the NDV strain CA02 replicates better in macrophages (HD11 and primary adherent splenocytes) than the NDV strain Anhinga/93. Notably, exchange of the HN or both F and HN genes of NDV Anhinga/93 by the corresponding genes from NDV CA02 markedly improved the ability of the chimeric viruses to replicate in macrophages. These results indicate that the F and HN proteins are determinants of NDV macrophage host range. This represents the first description of productive NDV infection in macrophages.