Virus Enumeration
Virus Enumeration - Related Videos
09:29
Algae Enumeration via Culturable Methodology
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2023
Source: Laboratories of Dr. Ian Pepper and Dr. Charles Gerba - The University of Arizona Demonstrating Author: Bradley Schmitz Algae are a highly heterogeneous group of microorganisms that have one common trait, namely the possession of photosynthetic pigments. In the environment, algae can cause problems for swimming pool owners by growing in the water. Algae can also cause problems in surface waters, such as lakes and reservoirs, due to algal blooms that release toxins. More recently, algae...
10:53
Serial Dilutions and Plating: Microbial Enumeration
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2023
Source: Jonathan F. Blaize1, Elizabeth Suter1, and Christopher P. Corbo1 1 Department of Biological Sciences, Wagner College, 1 Campus Road, Staten Island NY, 10301 Quantitative assessment of prokaryotes can be onerous given their abundance, propensity for exponential proliferation, species diversity within a population, and specific physiological needs. Compounding this challenge, is the four-phase nature in which bacteria replicate (lag, log, stationary and death). The ability to accurately...
10:57
Culturing and Enumerating Bacteria from Soil Samples
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2023
Source: Laboratories of Dr. Ian Pepper and Dr. Charles Gerba - The University of Arizona Demonstrating Authors: Bradley Schmitz and Luisa Ikner Surface soils are a heterogeneous mixture of inorganic and organic particles that combine together to form secondary aggregates. Within and between the aggregates are voids or pores that visually contain both air and water. These conditions create an ideal ecosystem for bacteria, so all soils contain vast populations of bacteria, usually over 1 million...
03:16
Processing of Infected Tissues for Bacterial Enumeration in a Mouse Co-Infection Model
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2026
Source: Lenhard, A., et al. A Mouse Model for the Transition of Streptococcus pneumoniae from Colonizer to Pathogen upon Viral Co-Infection Recapitulates Age-Exacerbated Illness. J. Vis. Exp. (2022)This video demonstrates the processing of lungs from a mouse co-infected with a pathogenic bacterium and a virus. Mincing, homogenizing, and plating the lung tissue allows quantification of bacterial load, indicating bacterial spread to the lungs and disease severity.
10:32
Enumeration of Neural Stem Cells Using Clonal Assays
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Cited by 5 •
2016
Neural stem cells (NSCs) refer to cells which can self-renew and differentiate into the three neural lineages. Here, we describe a protocol to determine NSC frequency in a given cell population using neurosphere formation and differentiation under clonal conditions.
FAQs
A sample may contain viral genomes without an equivalent number of infectious particles. Comparing nucleic acid estimates with infectious measurements therefore helps reveal changes in particle infectivity rather than viral burden alone. This distinction is important when interpreting replication, transmission, disease-related data, or treatment effects, because genome abundance does not by itself indicate how much virus can infect susceptible cells.
Plaque assays quantify infectious virus through visible plaques produced in susceptible cell cultures, whereas TCID50 estimates the dose that infects half of a set of cultured wells. Both assess infectivity, but they express the outcome through different experimental readouts. Selecting between them depends on whether plaque formation or infection across replicate wells best fits the study design.
The relationship between these measurements provides information about the functional quality of a viral preparation. Similar changes in infectious units and genome counts may support an interpretation of altered viral burden, while a divergence between them can indicate a shift in particle infectivity. This comparison adds context to measurements of replication and to evaluations of antiviral responses.
The intended measurement should guide method selection. When the study requires information about infectivity, researchers can use plaque formation in susceptible cell cultures or a TCID50 design based on infection across cultured wells. When estimating viral genomes is the priority, nucleic acid amplification is appropriate. Using more than one measurement can distinguish total genomic material from infectious virus.
These measurements allow investigators to follow pathogen growth while examining how the host responds to infection. Infectious-virus results can indicate changes in replication capacity, whereas genome measurements provide a complementary estimate of viral material. Together, they support interpretation of antiviral responses and help connect virological measurements with infection-related experimental outcomes.
Virus enumeration provides outcome measures for testing vaccine efficacy and therapeutic activity. A study can compare viral burden or infectious virus between experimental conditions, then assess whether an intervention changes replication or infectivity. Including both genome estimates and infectious measurements can clarify whether an observed effect reflects less viral material, reduced infectivity, or both.