Virus Quantification
Virus Quantification - Related Videos
02:37
Quantification of Infectious Hepatitis C Virus by Fluorescence Microscopy
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2026
Source: Ren, S., et al. A Protocol for Analyzing Hepatitis C Virus Replication. J. Vis. Exp. (2014)This video demonstrates the fluorescence focus assay used to quantify infectious Hepatitis C virus in cell culture. It demonstrates the serial dilution of viral supernatant, the infection of hepatoma cells, and the detection of viral replication sites using antibody-based fluorescence microscopy.
03:43
Virus Plaque Assay: A Technique to Measure Infectious Herpes Simplex Virus via Quantification of Plaques Formed in Monolayer of Virus-Infected Cells
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2025
This video describes the virus plaque assay of the infectious herpes simplex virus or HSV. The diluted viral particles are inoculated to the monolayer of epithelial cells. Upon incubation, the virus forms plaques and is counted visually to determine the infectious virus titer.
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...
07:26
Virus Propagation and Cell-Based Colorimetric Quantification
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2023
The present protocol describes the propagation of Zika virus (ZIKV) in Vero African green monkey kidney cells and the quantification of ZIKV using cell-based colorimetric immunodetection methods in 24-well and 96-well (high throughput) formats.
09:14
Isolation and Quantification of Epstein-Barr Virus from the P3HR1 Cell Line
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Cited by 1 •
2022
This protocol permits the isolation of Epstein-Barr virus particles from the human P3HR1 cell line upon inducing the viral lytic cycle with phorbol 12-myristate 13-acetate. DNA is subsequently extracted from the viral preparation and subjected to real-time PCR to quantify the viral particle concentration.
FAQs
Virus quantification can report either infectious activity or genome abundance, and those outputs are not interchangeable. Plaque and focus-forming assays register viral replication in susceptible cells, whereas quantitative PCR detects viral genetic material. A sample may therefore contain many genome copies but fewer infectious virions. Interpreting results requires matching the measurement to the biological question.
Plaque and focus-forming assays connect the measurement to replication in infected cells. As infection proceeds, infected-cell zones provide the basis for counting infectious activity, making these assays useful when the question concerns particles capable of initiating productive infection. They differ from genome-based measurements, which do not establish that the detected material retains infectivity.
Quantitative PCR adds a genome-level readout that can be applied when researchers need to measure viral genetic material rather than infectious activity. It can complement cell-based assays by showing whether changes in infectious output are accompanied by changes in genome abundance. This paired interpretation helps prevent genome copies from being treated as a direct count of infectious virions.
Viral burden becomes more informative when interpreted alongside host outcomes. In immunology and infection studies, measurements can be compared with disease severity or immune responses to examine how viral abundance relates to pathology and host defense. The relationship is not established by quantification alone, but the measurements provide the basis for those comparisons.
The experimental objective determines which measurement is most appropriate. Plaque or focus-forming assays are suited to questions about infectious activity and replication in cells, while quantitative PCR addresses the abundance of viral genomes. Using both approaches can be valuable when researchers need to distinguish changes in total genetic material from changes in infectious virus.
Virus quantification supports replication-kinetics studies by allowing viral measurements to be compared across the course of an infection. Researchers can examine how viral abundance or infectious activity changes over time and determine whether different pathogen strains show distinct patterns. These comparisons help connect the progression of replication with experimental infection outcomes.
Vaccines and antiviral treatments can be evaluated by comparing viral measurements between experimental conditions. Reduced infectious activity or lower genome abundance may indicate an altered viral burden, although the two readouts should not be assumed to represent the same outcome. Combining quantification with immune-response measurements helps assess both pathogen control and host protection.