Viral Titering
Viral Titering - Related Videos
08:35
Production and Titering of Recombinant Adeno-associated Viral Vectors
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Cited by 137 •
2011
Recombinant adeno-associated virus (rAAVs) vectors are becoming increasingly valuable for in vivo studies in animals. We describe how rAAVs can be produced in the laboratory and how these vectors can be titered to give an accurate reading of the number of infectious particles produced.
11:08
Packaging HIV- or FIV-based Lentivector Expression Constructs & Transduction of VSV-G Pseudotyped Viral Particles
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Cited by 16 •
2012
Lentiviral expression vectors are the most effective vehicles for stably expressing different effector molecules or reporter constructs in dividing and non-dividing mammalian cells and whole organisms. Here we provide a protocol on how to package lentivector expression constructs in pseudoviral particles and to transduce target cells using the pseudoviral particles.
09:28
Viral Concentration Determination Through Plaque Assays: Using Traditional and Novel Overlay Systems
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Cited by 441 •
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.
13:45
Using a Pan-Viral Microarray Assay (Virochip) to Screen Clinical Samples for Viral Pathogens
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Cited by 84 •
2011
The Virochip is a pan-viral microarray designed to simultaneously detect all known viruses as well as novel viruses on the basis of conserved sequence homology. Here we demonstrate how to run a Virochip assay to analyze clinical samples for the presence of both known and unknown viruses.
02:41
Concentration and Purification of Viral Particles
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2026
Source: Fricano-Kugler, C. J., et al. Designing, Packaging, and Delivery of High Titer CRISPR Retro and Lentiviruses via Stereotaxic Injection. J. Vis. Exp. (2016).This video demonstrates the step-by-step process for concentrating and purifying lentiviral particles from a mixed suspension containing host cell debris. The procedure utilizes centrifugation, filtration, and PEG-salt precipitation to isolate viral particles while removing soluble impurities. The final product is resuspended in a...
FAQs
Serial dilutions create a range of virus concentrations, allowing researchers to identify a dilution that produces countable plaques, infected cell foci, or cytopathic effects. Comparing responses across dilutions supports calculation of infectious units rather than relying on a single potentially overcrowded or indistinct measurement. The dilution series also makes samples with different starting concentrations more comparable.
These readouts provide observable evidence that infectious virus affected susceptible cultured cells. Plaques and infected foci can be quantified directly, while cytopathic effects provide a measurable cellular response used in the assay. Selecting a suitable readout determines how infectious virus is quantified and whether results are reported as plaque-forming units or another assay-based measure.
Susceptible cells provide the biological system in which virus can produce a measurable effect. Without an appropriate cellular response, the assay cannot distinguish infectious activity through plaques, infected foci, or cytopathic effects. This requirement makes the cell culture component central to interpreting a sample's infectious concentration, rather than simply detecting virus-related material.
PFU and TCID50 are reporting formats linked to different ways of quantifying infectious virus in cultured cells. Plaque-based measurements are commonly expressed as plaque-forming units, whereas TCID50 represents another assay-based infectious measurement. The reported unit therefore communicates how the infectious effect was detected and supports consistent comparison within and across experiments.
A typical workflow begins with preparing serial dilutions of the virus-containing sample. Researchers then expose susceptible cultured cells to those dilutions and monitor the cultures for plaques, infected cell foci, or cytopathic effects. They quantify the selected endpoint and use the dilution results to calculate the infectious concentration, producing a standardized value for later experiments.
Viral titering is useful when experiments require a standardized inoculum or quantitative comparison of infectious virus. It supports studies of viral replication, neutralization, vaccines, antiviral treatments, and host immune responses. Reliable titers help researchers interpret whether differences between conditions reflect altered infection or treatment and immune effects, while improving reproducibility across infection models.