Infectious Center Assay
Infectious Center Assay - Related Videos
05:01
Quantifying Infectious Viruses in Water Samples Using an In Vitro Total Culturable Virus Assay
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2026
Source: Fout, G. S., Cashdollar, J. L. EPA Method 1615. Measurement of Enterovirus and Norovirus Occurrence in Water by Culture and RT-qPCR. II. Total Culturable Virus Assay. J. Vis. Exp. (2016)This video demonstrates the use of a total culturable virus assay to quantify infectious viruses in water samples. It outlines host cell inoculation, observation of cytopathic effect, and statistical quantification of infectious virus concentration.
04:32
Plaque Titration Assay for Quantification of Infectious Respiratory Syncytial Virus
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2026
Source: Bouillier, C., et al. Generation, Amplification, and Titration of Recombinant Respiratory Syncytial Viruses. J. Vis. Exp. (2019)The video demonstrates a plaque titration assay used to quantify infectious recombinant respiratory syncytial virus (RSV) in epithelial cell monolayers. It presents the infection of host cells with serially diluted viral suspensions, the restriction of viral spread by a cellulose-based semi-solid overlay, and the formation of localized plaques from cytopathic...
07:23
Detection of Infectious Virus from Field-collected Mosquitoes by Vero Cell Culture Assay
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Cited by 19 •
2011
We describe a method to process and screen field-collected mosquitoes for a diversity of viruses by Vero cell culture assay. By employing this technique, we have detected 9 different viruses from 4 taxonomic families in mosquitoes collected in Connecticut.
13:48
Reverse Genetics Mediated Recovery of Infectious Murine Norovirus
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Cited by 24 •
2012
Noroviruses are a major cause of gastroenteritis yet molecular techniques for their characterisation are still relatively new. Here we report two different reverse genetics approaches for the efficient recovery of murine norovirus (MNV), the only member of this genus which can be propagated in cell culture.
02:40
Amplification and Recovery of Infectious Bacteriophages
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2026
Source: Rustad, M. et al. Synthesis of Infectious Bacteriophages in an E. coli-based Cell-free Expression System. J. Vis. Exp. (2017)This video demonstrates the amplification and recovery of infectious bacteriophages from E. coli cultures. It outlines the steps for plaque isolation, phage replication, controlled lysis, and purification.
FAQs
Rather than measuring all viral material present in a sample, the assay focuses on cells that retain the ability to release infectious virus or transmit infection. Infected cells are diluted and exposed to susceptible cells, so the resulting count reflects functional infectivity associated with cells. This distinction is useful when viral material is present but does not represent infectious activity.
A permissive cell monolayer provides the susceptible cellular environment needed for infection to spread from an infectious cell. If the plated cells are not permissive, transmission may not generate a visible focus or plaque, reducing what the assay can reveal. Thus, the monolayer links cell-associated infectivity to a countable localized signal.
Localized foci or plaques convert transmission events into countable readouts. A focus or plaque forms when an infectious cell initiates infection in neighboring susceptible cells; immunostaining can identify infected areas, while cytopathic changes provide an alternative visible indication. The selected readout determines how infectious centers are recognized and counted after plating.
The workflow begins with infected cells, followed by dilution and plating onto a permissive cell monolayer. After infectious cells initiate localized transmission, investigators identify the resulting foci or plaques through immunostaining or visible cytopathic changes. Counting these localized signals provides an estimate of infectious centers and supports analysis of cell-associated infectivity.
Researchers can apply the assay when they need to evaluate viral dissemination or transmission between cells rather than simply detect viral material. It can also compare how susceptible host cells are to infection or how effectively infection remains associated with cells. These uses make the method relevant to studies of pathogen spread and cellular infection behavior.
In immunology and infection research, changes in infectious-center counts can help assess immune-mediated control of infection. The assay can also evaluate neutralizing antibody activity by examining how antibody activity affects the ability of infected cells to generate infectious transmission. Results connect an immune intervention with a functional outcome based on detectable infectious centers.