Agarose Overlay
Agarose Overlay - Related Videos
04:33
Evaluation of a Liquid Overlay System for Viral Plaque Assays
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2026
Source: Baer, A. and Kehn-Hall, K. Viral Concentration Determination Through Plaque Assays: Using Traditional and Novel Overlay Systems. J. Vis. Exp. (2014).This video demonstrates the use of a liquid microcrystalline cellulose-based overlay in a plaque-based assay by comparing its effectiveness in viral plaque formation with that of a traditional semi-solid agarose overlay.
09:28
Viral Concentration Determination Through Plaque Assays: Using Traditional and Novel Overlay Systems
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Cited by 466 •
2014
Plaque assays are the gold standard for viral quantification, utilizing entrapping overlays on host cellular monolayers to determine viral titers. While various semisolid overlays have traditionally been used, here we demonstrate plaque techniques comparing semisolid overlays to a novel liquid microcrystalline cellulose among several families of viruses.
06:38
Use of the Soft-agar Overlay Technique to Screen for Bacterially Produced Inhibitory Compounds
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Cited by 141 •
2017
We describe a simple method for screening bacterial cultures for the production of compounds inhibitory towards other bacteria.
04:26
Agarose-Based Preparation of Human Precision-Cut Lung Slices
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2025
In this video, we describe a procedure to inflate isolated human lungs with agarose and prepare human precision-cut lung slices. The prepared ex vivo lung slices can be used for further immunologic experiments.
03:17
Soft Agar Overlay Assay for Detecting Bacteriocin-Mediated Killing in Pseudomonas syringae
0 Views •
2025
Source: Hockett, K. L., and Baltrus, D. A. Use of the Soft-agar Overlay Technique to Screen for Bacterially Produced Inhibitory Compounds. J. Vis. Exp. (2017)This video demonstrates the procedure for detecting bacteriocin-mediated killing by spotting supernatant from an antibiotic-induced donor strain onto a soft agar overlay containing a test strain. Clear zones formed after incubation indicate bacterial inhibition.
FAQs
The semisolid overlay restricts newly produced virions from moving broadly through the surrounding nutrient medium. Instead, progeny remain concentrated near initially infected cells and reach neighboring cells in a localized pattern. This spatial confinement links successive rounds of infection to a discrete region of cell damage, making replication easier to visualize and quantify.
A plaque represents localized cell damage or death produced as infection spreads through nearby cells. Its presence shows that infectious virus has generated a detectable focus of injury, while the number of plaques provides the basis for estimating infectious viral titer. Thus, plaque assays translate cellular outcomes into a quantitative measure of infectious material.
Because the assay records whether infection produces localized damage in a cell layer, it can reveal differences in host-cell susceptibility and viral replication behavior. Comparing plaque formation under the same assay framework helps researchers examine how readily a virus infects the available cells and how its spread manifests across the monolayer.
Researchers first inoculate a cell monolayer with virus, then cover the cells with nutrient medium containing agarose. As infectious particles replicate and move to neighboring cells within the restricted region, localized damage becomes visible as plaques. Counting those plaques provides an estimate of infectious viral titer and turns the assay into a measurable infection workflow.
An antiviral condition can be assessed by examining its effect on plaque formation in the infected cell layer. Changes in the number or detectability of localized plaques can provide evidence that viral infection or replication has been altered. This makes the assay useful for comparing antiviral activity through a visible, quantifiable infection outcome.
The approach connects pathogen behavior with a host-cell outcome that can be observed directly in a monolayer. It supports measurement of infectious virus while enabling comparisons of host-cell susceptibility, viral replication, and antiviral activity. Consequently, researchers can study infection as both a property of the pathogen and an interaction with the available host cells.