Identification of a human respiratory syncytial virus phosphoprotein domain required for virus-like-particle formation

• Published in: Virology (New York, N.Y.) N.Y.), 2019-06, Vol.532, p.48-54
• Main Authors: Meshram, Chetan D., Oomens, Antonius G.P.
• Format: Article
• Language: English
• Subjects: Assembly; Phosphoprotein; Respiratory syncytial virus; Virus-like-particle
• ISSN: 0042-6822; 1096-0341
• DOI: 10.1016/j.virol.2019.04.001

Perceived inefficiency and inadequate knowledge of the human respiratory syncytial virus (hRSV) assembly process present a hurdle for large-scale production of authentic hRSV virus-like particles (VLPs) for vaccine purposes. We previously established that the matrix protein, phosphoprotein (P), and fusion protein carboxy-terminus were sufficient to generate VLPs that resemble filamentous wildtype hRSV. Here, the contribution of P was examined. By co-expressing matrix, fusion, and modified P proteins, a ser/thr-rich P region (residues 39–57) was found to be critical for VLP formation, whereas the oligomerization domain was not. Substitutions throughout region 39–57 inhibited VLP formation and relevant amino acids were identified. Phosphomimetic substitutions of serines and threonines inhibited VLP formation; Phosphoblatant substitutions did not. The data show that P not only co-regulates replication and transcription but also has an important role in assembly, mediated by a separate domain that likely interacts with M and/or F and is highly regulated by phosphorylation. •A ser/thr -rich viral assembly domain (AD) was identified in the RSV phosphoprotein.•Several AD residues blocked VLP formation when individually mutated to alanine.•Phosphomimetic substitutions of ser/thr in the AD blocked VLP formation.•The phosphoprotein is multifunctional and highly regulated by phosphorylation.