NS2 of respiratory syncytial virus causes G2/M accumulation in HeLa/Fucci(CA)2 cells.

The cell cycle is a fundamental mechanism that regulates eukaryotic cell proliferation. It comprises the G1, S, G2, and M phases and is tightly controlled by cyclin/cyclin-dependent kinase complexes. Many viruses manipulate the host cell cycle to create a favorable environment for replication. In particular, RNA viruses such as Hepatitis C virus and human immunodeficiency virus interfere with cell cycle progression. Human respiratory syncytial virus (RSV), an RNA virus that infects the respiratory tract, suppresses the cell cycle. However, previous studies did not clearly distinguish between infected and uninfected cells, consequently limiting the interpretability of their results. Therefore, we utilized recombinant RSV expressing a fluorescent reporter in combination with HeLa-Fucci cells to enable the real-time visualization of cell cycle progression. This system enabled clear distinction between infected and uninfected cells. In this study, RSV infection induced cell cycle arrest at the G2 phase. This arrest was attributed to the viral nonstructural protein NS2. The fully infectious RSV system developed in this study provides novel and physiologically relevant insights into the mechanisms underlying RSV modulation of the host cell cycle to facilitate viral replication and pathogenesis. These findings may enable the identification of novel antiviral targets and development of therapeutic strategies.