Lytic Units
Lytic Units - Related Videos
01:30
Lytic Cycle of Bacteriophages
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2019
Bacteriophages, also known as phages, are specialized viruses that infect bacteria. A key characteristic of phages is their distinctive “head-tail” morphology. A phage begins the infection process (i.e., lytic cycle) by attaching to the outside of a bacterial cell. Attachment is accomplished via proteins in the phage tail that bind to specific receptor proteins on the outer surface of the bacterium. The tail injects the phage’s DNA genome into the bacterial cytoplasm. In the lytic replication...
07:10
Establishment and Quantification of De Novo Lytic Infection by Cell-free Kaposi's Sarcoma-Associated Herpesvirus
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2025
This protocol describes an in vitro system to model de novo lytic infection of Kaposi's sarcoma-associated herpesvirus using BAC16-derived virions. The method enables investigation of early viral replication and dissemination. Infectious virus production is quantified by GFP-based infectious units assays and real-time PCR of encapsidated viral genomes.
11:28
Dissecting Host-virus Interaction in Lytic Replication of a Model Herpesvirus
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Cited by 2 •
2011
We describe a protocol to identify key roles of host signaling molecules in lytic replication of a model herpesvirus, gamma herpesvirus 68 (γHV68). Utilizing genetically modified mouse strains and embryonic fibroblasts for γHV68 lytic replication, the protocol permits both phenotypic characterization and molecular interrogation of virus-host interactions in viral lytic replication.
02:52
Inducing the Prophage Lytic Replication for Transcriptomic Analysis
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2026
Source: Krishnamurthi, R., et al. Understanding the Impact of Temperate Bacteriophages on Their Lysogens Through Transcriptomics. J. Vis. Exp. (2024)This video demonstrates the induction of lytic replication in a prophage integrated into the bacterial genome and the capture of gene expression changes through timed sampling for transcriptomic analysis.
01:20
Viral Replication: Lytic Cycle
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2025
Bacteriophages, or phages, are viruses that specifically infect bacteria. Among them, T-even bacteriophages, such as T4, exhibit a well-characterized lytic replication cycle in Escherichia coli (E. coli). This process ensures the rapid proliferation of the virus while ultimately leading to the destruction of the bacterial host.Attachment and DNA InjectionThe infection process begins with the recognition and binding of the T4 phage to the E. coli cell surface. Tail fibers of the phage...
FAQs
Effector cells first recognize susceptible target cells, then use perforin to disrupt the target-cell membrane and deliver granzymes. These molecules initiate apoptosis, the programmed cell-death process that supplies the assay’s measurable endpoint. Because the readout reflects successful target destruction, changes in either recognition or killing efficiency can alter the calculated cytotoxic activity.
A defined destruction threshold converts cytotoxicity into a standardized quantitative comparison. The calculation expresses how much effector-cell material or sample is needed to reach that same level of target-cell death. This allows investigators to compare immune responses even when samples differ in potency, cell number, or experimental treatment.
Cytokines, therapies, and other experimental conditions can modify the observed killing activity, changing the amount of effector cells or sample needed to destroy the defined target fraction. The assay therefore captures the functional outcome of immune activation or suppression rather than merely recording the presence of natural killer cells or cytotoxic T lymphocytes.
A typical workflow combines effector cells, such as natural killer cells or cytotoxic T lymphocytes, with susceptible target cells under defined assay conditions. Investigators then measure the resulting target-cell death, identify the amount of effector cells or sample associated with the selected destruction fraction, and use that relationship to calculate lytic activity.
Lytic-unit measurements are useful when investigators need to compare cytotoxic immune responses directed against infection- or tumor-associated targets. The quantitative result can show whether one immune sample, treatment, or experimental condition produces greater or lower target-cell killing, supporting studies of host defense and immune regulation.
Researchers can compare lytic-unit values before and after exposure to a cytokine, therapy, or other condition. A change in the amount of effector material required to reach the defined target-cell death fraction indicates altered cytotoxic performance. This makes the assay useful for evaluating how experimental interventions regulate cellular killing rather than simply documenting cell identity.