Viral Quantification
Viral Quantification - Related Videos
02:31
Sample Preparation for Luciferase-Based Viral Quantification
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2026
Source: Garcia, V., et al. High-throughput Titration of Luciferase-expressing Recombinant Viruses. J. Vis. Exp. (91), e51890, doi:10.3791/51890 (2014).This video demonstrates the preparation of cell culture samples to assess viral load using a luciferase-based assay. It outlines the process of infecting epithelial cells with a genetically modified virus, transferring viral supernatants and standards into assay wells, and promoting viral entry through centrifugation and incubation. The...
03:40
Plaque Assay–Based Quantification of Viral Load in an Infected Mouse Tissue Sample
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2026
Source: Morales Vasquez, D., et al. Live Imaging and Quantification of Viral Infection in K18 hACE2 Transgenic Mice Using Reporter-Expressing Recombinant SARS-CoV-2. J. Vis. Exp. (2021)This video demonstrates the protocol for carrying out plaque assay–based viral titration for quantifying infectious virus levels in tissue sample collected from a virus–infected mouse model.
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A Streamlined, Label-Free Real-Time 50% Tissue Culture Infectious Dose (TCID50) Assay using Impedance for Automated Viral Titer Quantification
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2026
The TCID50 assay reported here leverages label-free real-time impedance measurements and the system's Virology module to objectively monitor virus-induced cytopathic effects (CPE) in real time. This streamlined assay significantly reduces hands-on time while supporting high-throughput, quantitative kinetic CPE measurements and enabling automated, real-time TCID50 calculations.
02:23
Visualizing the Effect of pH on Solubilization of the Influenza A Viral Core
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2026
Source: Stauffer, S. et al., In Vitro Disassembly of Influenza A Virus Capsids by Gradient Centrifugation. J. Vis. Exp. (2016)This video demonstrates the effect of pH on the solubilization of influenza A viral cores. Gel electrophoresis and protein staining reveal the progressive disassembly of the core structure under acidic conditions.
00:57
Viral Recombination
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2019
Cells are sometimes infected by more than one virus at once. When two viruses disassemble to expose their genomes for replication in the same cell, similar regions of their genomes can pair together and exchange sequences in a process called recombination. Alternatively, viruses with segmented genomes can swap segments in a process called reassortment. Viral Recombination Can Create New Diseases Some diseases can infect multiple species. For example, pigs can be infected by some human and...
FAQs
Viral quantification can produce different values depending on whether the assay measures infectious activity or viral genomes. Plaque formation and cytopathic effects depend on virus particles that can infect and replicate in susceptible cells, whereas quantitative PCR estimates genome copies. Consequently, genome abundance may exceed the amount of replication-competent virus, so the readout must match the research question.
Serial dilution separates samples into concentrations where plaques or cytopathic effects can be measured in susceptible cells. Those cells provide the biological system needed to reveal replication-competent virus. The resulting signal reflects infectious activity rather than simply the presence of viral genetic material, making this approach useful for comparing viral growth or standardizing an infectious dose.
Quantitative PCR estimates how many viral genomes are present in a sample, while cell-based assays measure infectious activity. Genome measurements are valuable for following viral abundance, but they do not establish that every detected genome belongs to a replication-competent particle. Pairing both readouts gives a more complete view of infection and antiviral responses.
Researchers serially dilute the sample, apply the dilutions to susceptible cells, and measure plaque formation or cytopathic effects. Dilution creates a range in which the cell-based signal can be assessed instead of relying on an overly concentrated sample. This workflow supports estimation of infectious activity and provides a basis for comparing viral growth between samples.
Quantitative PCR is especially informative when the objective is to estimate viral genome abundance. It can complement infectious assays in studies of infection, immune control, and antiviral responses because genome measurements may not track replication-competent virus directly. Using both readouts helps distinguish changes in detected genetic material from changes in infectious activity, strengthening interpretation of experimental outcomes.
It supports viral growth analysis, dose standardization, vaccine evaluation, antiviral testing, transmission studies, and assessment of immune responses that control infection. In vaccine or antiviral experiments, quantification supplies a measurable outcome for comparing conditions. In immunology studies, selecting infectious or genome-based readouts helps determine whether the experiment captures replication-competent virus, viral genomes, or complementary aspects of infection.