Arrested spread of vesicular stomatitis virus infections in vitro depends on interferon‐mediated antiviral activity

Abstract

A quantitative understanding of the innate immune response will enable its recruitment against emerging, poorly characterized, or weaponized viral pathogens. To gain insights into how the innate responses can limit viral spread, we used quantitative focal infections to study how the spread of recombinant vesicular stomatitis viruses (VSV) on baby hamster kidney (BHK) and delayed brain tumor (DBT) cell monolayers is affected by innate cellular antiviral responses. We observed that rates of infection spread correlated with one-step growth rankings for four ectopic VSV strains: N1, N2, N3, and N4. However, this correlation was lost for M51R, a recombinant VSV mutant that lacks the ability to shut-off host gene expression. In BHK cells, M51R spread at two-thirds the rate of the recombinant control virus, XK3.1, even though their one-step growth was comparable. In DBT cells, M51R infections failed to spread beyond the site of inoculation. Addition of anti-interferon antibody restored M51R spread and one-step growth to wild-type levels. Interestingly, the antibody enhanced the spread of wild-type virus but not its growth. These results suggest that while the rate of viral spread generally correlates with the rate of viral growth, the induction of cellular antiviral activities can be in some cases, the overriding factor in both spread and growth. In summary, focal infections enabled us to visualize and quantify how viral spread was inhibited by cellular antiviral activities. This study demonstrates a mechanism for quantifying how innate cellular responses can mitigate infection spread in vitro.

High-Throughput Single-Cell Kinetics of Virus Infections in the Presence of Defective Interfering Particles

“…11), suggesting the presence of proviral factors in cell populations that are not available to isolated cells or the enrichment of antiviral factors by isolated cells. Common antiviral factors include interferons (IFNs), and IFN-mediated responses can be triggered by DIPs (63, 64); however, the host BHK cells used here lack such responses (65,66). Alternatively, confinement of cells to microwells can reduce the capacity of cells to grow, as reflected by longer G 1 and shorter G 2 /M phases of the cell cycle (67), conditions that are consistent with lower average productivities of VSV from BHK cells (51).…”

Image-Guided Modeling of Virus Growth and Spread

“…One-step growth infection of cell monolayers were performed as described in Lam, Duca, and Yin (15).…”

“…For this virus/host system, the images demonstrate three prominent features: (1) the infection propagates unimpeded outward radially for the first three images, (2) the intensity of the measurement amplifies from the first to the third measurement, and (3) the infection spread is halted after the third image and the intensity of the measurement diminishes. This particular cell line is known to have an antiviral strategy, namely the interferon signaling pathway (15,21). We now build a model to quantitatively capture all of these features.…”

Cell-Type-Specific Growth Restriction of Vesicular Stomatitis Virus polR Mutants Is Linked to Defective Viral Polymerase Function

“…Host range defects can also result from virus mutations that alter the ability of the virus to counter host cell antiviral responses. For instance, wild-type (wt) VSV Indiana strains generally shutdown host cell functions rapidly under single-cycle infection conditions, which limits interferon (IFN) production, but mutants defective in host cell shutoff display strong growth restriction at low multiplicities of infection (MOI) in IFN-competent cells (1,16,27,51). We document here a distinctly different instance of cell-type-specific growth restriction for a VSV mutant that displays aberrant viral RNA synthesis.…”