Analysis of Synchronous and Asynchronous In Vitro Infections with Homologous Murine Norovirus Strains Reveals Time-Dependent Viral Interference Effects

Figures

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  Figure 1. Workflow of the experimental set-up to analyse synchronous and asynchronous in vitro infections with homologous murine norovirus strains MNV-1 WU20 and CW1. MOI = Multiplicity of infection; ORF = Open Reading Frame; qPCR = quantitative polymerase chain reaction.

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  Figure 2. Genomic quantification on 5′ genome ends establishing raw genomic copy numbers (top) and relative proportions of mean genomic copies (below) of co- or superinfecting murine noroviruses MNV-1 WU20 and CW1 in viral progenies 24 h post co- or superinfection. Genomic copy numbers and their relative proportions resulting from one co-infection (t0) and seven asynchronous infections (primary infection: WU20; superinfection at half-hour to 24-h delays (t0.5 to t24): CW1) are shown. Varying multiplicities of infection (MOI) were analysed; the MOI of primary infecting WU20 remained stable at 1 throughout all assays while the MOI of superinfecting CW1 varied between 0.1 (left panels), 1 (middle panels), and 10 (right panels). Black bars represent WU20, grey bars represent CW1. Differences in yield between mean WU20 and CW1 genome copies were analysed using GraphPad Prism 7 (Graph-Pad Software) and p values were determined using two-sided unpaired-sample t tests, where *** p ≤ 0.001, ** p ≤ 0.01, and * p ≤ 0.05.

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  Figure 3. Relative proportions of viable co- or superinfecting murine noroviruses MNV-1 WU20 and CW1 after plaque purification and amplification. Black bars show the proportion of WU20, grey bars show the proportion of CW1, and striped bars indicate mixed signals of both WU20 and CW1 in viral progenies amplified from 36 plaques per condition. One coinfection (t0) and seven asynchronous infections (primary infection: WU20; superinfection at half-hour to 24-h delays (t0.5 to t24): CW1) and varying multiplicities of infection (MOI) were analysed; the MOI of primary infecting WU20 remained stable at 1 throughout all assays while the MOI of superinfecting CW1 varied between 0.1 (left panel), 1 (middle panel), and 10 (right panel)).