ViralPlaque: a Fiji macro for automated assessment of viral plaque statistics.

Marco Cacciabue,Anabella Currá,Maria I Gismondi

doi:10.7717/peerj.7729

Abstract

Plaque assay has been used for a long time to determine infectious titers and characterize prokaryotic and eukaryotic viruses forming plaques. Indeed, plaque morphology and dimensions can provide information regarding the replication kinetics and the virulence of a particular virus. In this work, we present ViralPlaque, a fast, open-source and versatile ImageJ macro for the automated determination of viral plaque dimensions from digital images. Also, a machine learning plugin is integrated in the analysis algorithm for adaptation of ViralPlaque to the user’s needs and experimental conditions. A high correlation between manual and automated measurements of plaque dimensions was demonstrated. This macro will facilitate reliable and reproducible characterization of cytolytic viruses with an increased processing speed.

Highlights

Plaque assay is a typical test originally used for bacteriophage characterization and subsequently adapted to eukaryotic viruses to estimate infectious titers or to perform clonal purification of viral agents (D’Hérelle & Smith, 1926; Dulbecco, 1952)
Viruses used for this study were foot-and-mouth disease virus (FMDV) isolates of serotype A and vesicular stomatitis Indiana virus (VSV)
We tested the ability of the ViralPlaque macro to detect and measure viral plaques accurately from low resolution images

Summary

Introduction

Plaque assay is a typical test originally used for bacteriophage characterization and subsequently adapted to eukaryotic viruses to estimate infectious titers or to perform clonal purification of viral agents (D’Hérelle & Smith, 1926; Dulbecco, 1952). Beyond these uses, formation of viral plaques is a relevant phenotypic feature that can withhold essential information of the virus under study. Cellular monolayers are fixed and counterstained with neutral red or crystal violet solutions, which facilitates the identification of the plaques formed.

Methods

Results

Conclusion