Investigating the interrelation of RSV infection and host cell cycle state

Abstract

Respiratory syncytial virus (RSV) infections are the leading cause of acute lower respiratory infections (ALRI) among young children and the elderly. The RSV virion contains a negative-sense single-stranded RNA genome (vRNA) that encodes eleven proteins that facilitate the propagation of the viral life cycle in infected cells. Progressing RSV infections in A549 cells are known to dysregulate the host cell cycle by inducing G1 phase arrest. Studies attempting to further investigate the patterns between of RSV infection and cell cycle progression are limited to bulk biochemical assays quantifying exclusively progressed RSV infections. We combined the intracellular vRNA visualization system RSV-P-ST/STAb-AausFP1 (P-STAb) developed by our group, with the PIP-FUCCI cell cycle reporter to generate a novel cell line (P-STAb-PIP-FUCCIG/R). We utilized this model to monitor early and progressed RSV infections, as well as RSV entry, with the aim to examine their interrelation with the host cell cycle state and cell cycle phase durations. Our results suggest possible preferential entry for RSV virions in S phase cells and disfavored entry in G1 cells, which could likely be attributed to cell cycle-dependent RSV receptor dynamics. We noted seemingly arrested infected cells with prolonged G1 phases, however some of these cells ultimately progressed into S phase, perhaps suggesting that RSV-induced G1 arrest can be reversed. We also discovered cases of infected cells entering prolonged mitosis. Progressed RSV infections displayed significant elongations in G1 and S phase compared to their non-progressing counterparts, with a large majority of cells stalling at G1. We theorize that these cycling patterns in progressed infections are caused by a buildup of oxidative stress concomitantly induced by RSV infection.