Name: prophage integration in bacterial cells
Uploaded: 2025-06-12T09:29:06.000Z
Duration: 1 min 16 s
Channel: JoVE

K12 Standards

Virginia  Standards of Learning

HIgh School

Biology

BIO.4

BIO.4.a

Viral Replication: Lysogenic Cycle

Le cycle lysogénique est un mécanisme de réplication virale dans lequel des bactériophages tempérés comme lambda intègrent leur ADN dans une cellule hôte sans lyse immédiate de la cellule. Cela commence lorsque le phage lambda se fixe à E. coli et injecte son matériel génétique. À l’intérieur de l’hôte, le génome linéaire circularise et s’intègre dans le chromosome bactérien par recombinaison spécifique au site, formant un prophage. Le prophage reste latent, les protéines répressives bloquant l’expression des gènes viraux. Au fur et à mesure que la bactérie se divise, elle copie le prophage et l’ADN, les transmettant aux cellules filles. Ce processus aboutit à trois résultats clés pour la cellule hôte : l’immunité à partir du même phage, l’acquisition de nouvelles caractéristiques bactériennes et le transfert horizontal de gènes. Le prophage peut être excisé du chromosome bactérien en cas de stress, comme l’exposition aux rayons UV, la famine ou les produits chimiques. Cela déclenche un passage au cycle lytique, où le virus se réplique rapidement et finit par provoquer la lyse cellulaire.

réplication virale – cycle lysogénique

Le cycle lysog&#233;nique est une strat&#233;gie de r&#233;plication virale essentielle qui permet aux bact&#233;riophages de persister &#224; l&#8217;int&#233;rieur des cellules h&#244;tes sans les d&#233;truire imm&#233;diatement. Ce processus est principalement observ&#233; chez les phages temp&#233;r&#233;s, comme le bact&#233;riophage lambda (&#955;), qui infecte Escherichia coli. Ce cycle permet au g&#233;nome viral de se transmettre au fil des g&#233;n&#233;rations bact&#233;riennes tout en maintenant la viabilit&#233; de la cellule h&#244;te.
Int&#233;gration du g&#233;nome viral
Apr&#232;s l&#8217;infection, le phage lambda s&#8217;attache &#224; la surface bact&#233;rienne et injecte son mat&#233;riel g&#233;n&#233;tique dans le cytoplasme. Le g&#233;nome lin&#233;aire du phage se circularise afin d&#8217;&#233;viter sa d&#233;gradation par les nucl&#233;ases de l&#8217;h&#244;te. Un processus sp&#233;cialis&#233;, appel&#233; recombinaison m&#233;di&#233;e par int&#233;grase, facilit&#233; par une int&#233;grase cod&#233;e par le phage, permet &#224; l&#8217;ADN viral de s&#8217;int&#233;grer dans le chromosome bact&#233;rien au niveau d&#8217;un site d&#8217;attachement sp&#233;cifique (attB chez E. coli). Le prophage r&#233;sultant reste dormant dans le g&#233;nome de l&#8217;h&#244;te.
Pendant la lysog&#233;nie, des prot&#233;ines r&#233;gulatrices r&#233;priment l&#8217;expression des g&#232;nes lytiques. La prot&#233;ine r&#233;presseur cI se lie aux r&#233;gions op&#233;ratrices du phage, emp&#234;chant la transcription des g&#232;nes n&#233;cessaires &#224; l&#8217;assemblage des virions et &#224; la lyse de la cellule h&#244;te. Cette r&#233;pression garantit la stabilit&#233; du prophage, tout en permettant la prolif&#233;ration bact&#233;rienne. Chaque fois que la bact&#233;rie se r&#233;plique, le prophage est copi&#233; avec l&#8217;ADN de l&#8217;h&#244;te, assurant une transmission verticale du g&#233;nome viral. Bien que les lysog&#232;nes soient g&#233;n&#233;ralement stables, certains prophages peuvent s&#8217;exciser spontan&#233;ment &#224; faible fr&#233;quence, m&#234;me en l&#8217;absence de stress environnemental.
La lysog&#233;nie offre des avantages &#233;volutifs &#224; la bact&#233;rie h&#244;te. La pr&#233;sence d&#8217;un prophage conf&#232;re une immunit&#233; contre une superinfection par le m&#234;me phage, car le r&#233;presseur emp&#234;che les infections suppl&#233;mentaires. La conversion lysog&#233;nique peut am&#233;liorer la comp&#233;titivit&#233; bact&#233;rienne en introduisant de nouveaux traits, comme la production de toxines chez Vibrio cholerae et Corynebacterium diphtheriae. En outre, les prophages contribuent au transfert horizontal de g&#232;nes, favorisant la diversit&#233; g&#233;n&#233;tique parmi les populations bact&#233;riennes.
La lysog&#233;nie repr&#233;sente une interaction dynamique entre les bact&#233;riophages et les bact&#233;ries, &#233;quilibrant la persistance virale avec le potentiel de prolif&#233;ration rapide. Bien que les prophages soient g&#233;n&#233;ralement h&#233;rit&#233;s de mani&#232;re stable, des pressions s&#233;lectives ou des &#233;v&#233;nements d&#8217;excision spontan&#233;e peuvent influencer leur persistance &#224; long terme dans les populations bact&#233;riennes.

Réplication virale – Cycle lysogénique

Le cycle lysog&#233;nique est une strat&#233;gie de r&#233;plication virale essentielle qui permet aux bact&#233;riophages de persister &#224; ...

Education

Enseignement

JoVE Core

Microbiology

Microbiologie

Unit

Unité

Viruses

Virus

KEY TERMS AND CONCEPTS

TERMES ET CONCEPTS CLÉS

prophage integration in bacterial cells

The lysogenic cycle shows how a bacteriophage can stay inside a bacterial cell without killing it right away. Temperate phages, such as bacteriophage lambda (λ), use this strategy to persist in Escherichia coli while the host cell remains alive.

After attachment to the bacterial surface, the phage injects its genetic material into the cytoplasm. The linear phage genome then circularizes, which helps protect it from host nucleases. Next, phage-encoded integrase carries out recombination that inserts the viral DNA into the bacterial chromosome at a specific attachment site, attB in E. coli. The integrated viral DNA is called a prophage, and it stays dormant in the host genome.

During lysogeny, the phage keeps lytic genes turned off. The cI repressor protein binds to phage operator regions and blocks transcription of genes needed for virion assembly and host lysis. This repression helps the prophage remain stable while the bacterial cell continues to grow and divide. Each time the bacterium replicates, the prophage is copied along with the host DNA, so the viral genome is passed to daughter cells.

Lysogens are usually stable, but some prophages can excise on their own at a low rate, even without stress. Lysogeny can also benefit the bacterium. The prophage can give immunity to superinfection by the same phage because the repressor blocks new infections. It can also cause lysogenic conversion, which may add new traits such as toxin production in Vibrio cholerae and Corynebacterium diphtheriae. In addition, prophages support horizontal gene transfer and increase genetic diversity among bacterial populations.

Prophage Integration in Bacterial Cells

introduction to virus

Virus Structure, Entry, and Replication

Viruses are biological entities that rely on host cells to make more copies of themselves. They do not have cells or their own metabolism, but they can show signs of life when they infect a host. Their basic structure includes a nucleic acid core, made of either DNA or RNA, surrounded by a protein coat called a capsid. Viruses are classified by the type of nucleic acid they contain and by their structure. Some viruses also have a lipid envelope that comes from the host cell membrane. Enveloped...

size and structure of viral genomes

How Viral Genomes Replicate

Viral genomes can be DNA or RNA, and their structure shapes how they replicate inside host cells. They may be linear or circular. They can also be single-stranded or double-stranded. These differences affect how a virus makes copies of itself and how it interacts with the host. RNA viruses usually have smaller genomes than DNA viruses. That smaller size is linked to high mutation rates and fast evolution. RNA virus polymerases often lack proofreading, so mistakes are more common. This helps...

viral replication: lytic cycle

T4 Phage Infection of E. coli

T4 phage infection of E. coli follows a lytic cycle that lets the virus make many copies fast. Bacteriophages, or phages, are viruses that infect bacteria, and T-even phages such as T4 are known for this well-studied process. The cycle ends with the destruction of the bacterial host. The first step is attachment to the E. coli cell surface. Tail fibers on the phage bind to receptor molecules on the bacterial outer membrane, which helps the virus find the correct host. After binding, the...

viral replication: lysogenic cycle

The lysogenic cycle shows how a bacteriophage can stay inside a bacterial cell without killing it right away. Temperate phages, such as bacteriophage lambda (λ), use this strategy to persist in Escherichia coli while the host cell remains alive. After attachment to the bacterial surface, the phage injects its genetic material into the cytoplasm. The linear phage genome then circularizes, which helps protect it from host nucleases. Next, phage-encoded integrase carries out recombination that...

dna bacteriophages

How DNA Phages Replicate in Bacteria

DNA bacteriophages are viruses that infect bacteria and use bacterial cell machinery to make more copies of themselves. They carry either single-stranded DNA (ssDNA) or double-stranded DNA (dsDNA), and each group uses a different replication strategy. Their life cycles also shape how they interact with hosts and how scientists use them in biotechnology and medicine. Some ssDNA phages keep their genomes very small and compact. The icosahedral phage ΦX174 shows this clearly because it uses...

viruses of archaea

Archaeal Virus Shapes and Extreme Survival

Archaeal viruses infect archaea that live in extreme places such as acidic hot springs and hydrothermal vents. These hosts often belong to the phyla Euryarchaeota and Crenarchaeota. The viruses help shape host evolution and gene transfer, which adds genetic diversity to microbial communities in harsh environments. Most archaeal viruses carry double-stranded DNA, or dsDNA, genomes. Some have single-stranded DNA, and some have RNA genomes. Their virions, or complete virus particles, show unusual...

viruses with rna genomes

RNA Virus Replication Strategies

RNA viruses use several replication strategies based on their genome type. They are grouped as positive-strand, negative-strand, or double-stranded RNA viruses. Some RNA viruses also use reverse transcription, which adds another layer to how they copy their genetic material. Positive-strand RNA viruses have genomes that can act like messenger RNA, or mRNA, as soon as they enter a cell. This lets the virus begin making proteins right away. Bacteriophage MS2 infects Escherichia coli by attaching...

the antiviral system of bacteria and archaea: crispr

the-antiviral-system-of-bacteria-and-archaea-crispr

How CRISPR Remembers Viral Infections

CRISPR is an adaptive immune system in bacteria and archaea that helps protect cells from viral infection. It works by identifying foreign genetic material, remembering it, and stopping the same invader later. In many cases, the main targets are bacteriophages, which are viruses that infect bacteria. The first defense step begins during an initial infection. Cas proteins, which are CRISPR-associated proteins, detect foreign DNA by looking for specific sequences called Protospacer Adjacent...

crispr/cas9 genome editing

CRISPR-Cas9 and DNA Repair in Cells

CRISPR-Cas9 uses a bacterial defense system to change DNA in cells. The CRISPR-Cas system first evolved in prokaryotes to protect bacteria from invading genetic material such as viruses and plasmids. Scientists later adapted it into a genome-editing tool for plants, animals, and humans. The key enzyme is Cas9, a DNA-cutting protein called an endonuclease from Streptococcus pyogenes. In the lab, a synthetic single guide RNA, or sgRNA, directs Cas9 to a chosen DNA site. The sgRNA matches the...

subviral agents

Viroids, Prions, and Satellite Viruses

Viroids, prions, and satellites are subviral agents that can cause infection even though they are not complete viruses. They resemble viruses in spread and disease, but each lacks one or more key viral parts, such as a capsid or the machinery needed for replication. Viroids are the simplest of these agents. They are circular, single-stranded RNA molecules with no protein coat. Viroids infect plants only and depend on host cell machinery to copy themselves. Host RNA polymerase replicates them...

key terms and concepts

Learn how temperate phages integrate into bacterial DNA, form prophages, and stay dormant during lysogeny while protecting and changing host cells.

Prophage Integration in Bacterial Cells | JoVE K12

JoVE Core Microbiology provides an engaging introduction to the microbial world and its influence on health, industry, and the environment. This comprehensive collection covers key concepts such as microbial structure, metabolism, genetics, and ecology. It introduces essential laboratory techniques and microscopy methods through visually engaging animations. Corresponding scientist-in-action videos bridge classroom concepts with real-world research and applications.

microbiology

Alabama Course of Study Science

9-12

Unity and Diversity

9-12.B.4.13.a

Introduction to Virus

Viruses are unique biological entities that blur the boundary between living and non-living systems. Although they lack cellular structure and metabolic ...

Size and Structure of Viral Genomes

Viral genomes exhibit remarkable diversity in size, structure, and composition, influencing their replication strategies and interactions with host cells. ...

Viral Replication: Lytic Cycle

Bacteriophages, or phages, are viruses that specifically infect bacteria. Among them, T-even bacteriophages, such as T4, exhibit a well-characterized ...

The lysogenic cycle is a crucial viral replication strategy that allows bacteriophages to persist within host cells without immediately destroying them. ...

DNA Bacteriophages

Bacteriophages, or phages, are viruses that specifically infect bacteria, utilizing their genetic material to hijack host cellular machinery for ...

Viruses of Archaea

Archaeal viruses play a crucial role in the ecosystems of extremophilic archaea, particularly those belonging to the phyla Euryarchaeota and ...

Viruses with RNA Genomes

RNA viruses are categorized into positive-strand, negative-strand, or double-stranded groups based on their genomic structure and replication mechanisms. ...

The Antiviral System of Bacteria and Archaea: CRISPR

CRISPR stands for Clustered Regularly Interspaced Short Palindromic Repeats is a adaptive immune system found in bacteria and archaea that protects ...

CRISPR/Cas9 Genome Editing

The CRISPR-Cas system serves as a bacterial defense mechanism against invading genetic elements such as viruses and plasmids, forming the foundation for ...

Subviral Agents

Subviral agents are infectious entities that resemble viruses but lack one or more viral components, such as a capsid or essential replication machinery. ...

The student will investigate and understand that bacteria and viruses have an effect on living systems. Key ideas include  viruses depend on a host for metabolic processes;

Binary Fission

Binary fission is the primary mode of asexual reproduction in prokaryotes, such as bacteria. It results in the production of two genetically identical ...

Generation Time

Bacterial generation time, the period required for a bacterial population to double during its exponential growth phase, serves as a critical measure of ...

Bacterial Growth Curve

The bacterial growth curve is a fundamental concept in microbiology that describes the dynamics of bacterial population growth in a closed system with ...

microbial-growth-measurement-direct-methods

Microbial Growth Measurement: Direct Methods

Direct methods for measuring microbial populations in a culture are essential tools in microbiology, providing quantitative data for various applications. ...

microbial-growth-measurement-indirect-methods

Microbial Growth Measurement: Indirect Methods

Estimating microbial growth is essential for understanding population dynamics and environmental adaptations. Indirect methods provide valuable insights ...

Microbial Growth Media

Microbial growth media are essential tools in microbiology, providing the nutrients and conditions necessary to cultivate and study microorganisms. These ...

Need for Obtaining Pure Cultures

Pure cultures, defined as the growth of a single microorganism species isolated from mixed populations, are fundamental tools in microbiological research ...

techniques-for-isolation-of-pure-cultures

Techniques for Isolation of Pure Cultures

Microorganisms are routinely cultured in the laboratory using various techniques to isolate, grow, and quantify them for further study. These methods rely ...

Factors Influencing Microbial Growth: pH

Microorganisms are classified as acidophiles, neutrophiles, or alkaliphiles based on their pH growth preferences, reflecting their adaptations to specific ...

factors-influencing-microbial-growth-temperature

Factors Influencing Microbial Growth: Temperature

Microorganisms display remarkable adaptations, enabling them to thrive in diverse ecological niches across a wide range of temperatures. Temperature ...

factors-influencing-microbial-growth-osmolarity

Factors Influencing Microbial Growth: Osmolarity

Osmolarity is the measure of solute concentration in a solution. It plays a critical role in determining water availability for organisms. Water moves ...

Oxygen Requirements and Growth Patterns

Microorganisms exhibit diverse oxygen requirements and growth patterns driven by their metabolic strategies and environmental adaptations. Oxygen, while ...

Biofilms

Biofilms are complex communities of microorganisms encased in a self-produced extracellular polysaccharide matrix attached to surfaces. These microbial ...

The student will investigate and understand that bacteria and viruses have an effect on living systems. Key ideas include the modes of reproduction/replication can be compared

BIO.4.b

Prokaryotic vs. Eukaryotic Cells

Prokaryotic and eukaryotic cells represent two fundamental types of cellular organization, differing significantly in structure, complexity, and function. ...

Microbial Morphologies 

Bacterial and archaeal cells exhibit remarkable diversity in shape and structure, critical in their adaptability and functionality. Among bacteria, the ...

Bacterial Cell Wall 

The bacterial cell wall is an essential structural component that encases the plasma membrane, preserving cellular integrity, determining shape, and ...

Archaeal Cell Wall

Archaeal cell walls are structurally and compositionally distinct from their bacterial counterparts, lacking the characteristic peptidoglycan layer found ...

Peptidoglycan Synthesis

Structure of PeptidoglycanPeptidoglycan is a vital structural component of the bacterial cell wall, providing mechanical strength and shape to the cell. ...

Plasma Membrane in Bacteria and Archaea

The plasma membrane is an essential cellular structure responsible for maintaining cellular integrity and regulating the selective transport of molecules. ...

Outer Layers of the Cell Envelope

The outermost layers of prokaryotic cells play a critical role in their survival, virulence, and interaction with the environment. These layers, often ...

Flagella and Motility in Bacteria

Flagella are specialized, thread-like structures that extend from a bacteria's cell envelope. They play a crucial role in motility and chemotaxis. Their ...

Fimbriae, Pili, and Axial Filaments

Fimbriae and pili are specialized bacterial surface structures that play pivotal roles in adhesion, genetic exchange, and motility. Composed primarily of ...

Cell Inclusions

Prokaryotic cells possess a variety of inclusions that play crucial roles in nutrient storage, metabolic processes, and environmental adaptation. These ...

Endospores and Sporulation

Endospores are specialized, dormant cells primarily formed by Gram-positive bacteria, including Bacillus and Clostridium, enabling survival under extreme ...

Nucleoid

The nucleoid represents a structurally and functionally distinct region within prokaryotic cells, where the cell's DNA and associated proteins are housed. ...

Surface Appendages of Archaea

Archaeal surface appendages are highly specialized structures essential for environmental adaptation, encompassing roles in adhesion, biofilm formation, ...

The student will investigate and understand that bacteria and viruses have an effect on living systems. Key ideas include  the structures and functions can be compared

BIO.4.c

Types of Microorganisms

Microorganisms are a diverse group of microscopic entities broadly categorized into cellular and acellular types based on their structural organization. ...

environmental-applications-of-microorganisms

Environmental Applications of Microorganisms

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community-dna-extraction-from-bacterial-colonies

Community DNA Extraction from Bacterial Colonies

Source: Laboratories of Dr. Ian Pepper and Dr. Charles Gerba - The University of Arizona
Demonstrating Author: Luisa Ikner
Traditional methods of analysis ...

detecting-environmental-microorganisms-with-polymerase-chain-reaction

Detecting Environmental Microorganisms with the Polymerase Chain Reaction and Gel Electrophoresis

Source: Laboratories of Dr. Ian Pepper and Dr. Charles Gerba - Arizona University
Demonstrating Author: Bradley Schmitz
Polymerase chain reaction (PCR) is ...

rna-analysis-of-environmental-samples-using-rt-pcr

RNA Analysis of Environmental Samples Using RT-PCR

Source: Laboratories of Dr. Ian Pepper and Dr. Charles Gerba - The University of Arizona
Demonstrating Author: Bradley Schmitz
Reverse ...

quantifying-environmental-microorganisms-and-viruses-using-qpcr

Quantifying Environmental Microorganisms and Viruses Using qPCR

Source: Laboratories of Dr. Ian Pepper and Dr. Charles Gerba - The University of Arizona
Demonstrating Author: Bradley Schmitz
Quantitative polymerase ...

water-quality-analysis-via-indicator-organisms

Water Quality Analysis via Indicator Organisms

Source: Laboratories of Dr. Ian Pepper and Dr. Charles Gerba -The University of Arizona
Demonstrating Author: Luisa Ikner
Water quality analysis monitors ...

isolation-of-fecal-bacteria-from-water-samples-by-filtration

Isolation of Fecal Bacteria from Water Samples by Filtration

Source: Laboratories of Dr. Ian Pepper and Dr. Charles Gerba - The University of Arizona
Demonstrating Author: Luisa Ikner
The quality of water destined ...

detection-of-bacteriophages-in-environmental-samples

Detection of Bacteriophages in Environmental Samples

Source: Laboratories of Dr. Ian Pepper and Dr. Charles Gerba - The University of Arizona
Demonstrating Author: Alex Wassimi
Viruses are a unique group of ...

culturing-and-enumerating-bacteria-from-soil-samples

Culturing and Enumerating Bacteria from Soil Samples

Source: Laboratories of Dr. Ian Pepper and Dr. Charles Gerba - The University of Arizona
Demonstrating Authors: Bradley Schmitz and Luisa Ikner
Surface ...

bacterial-growth-curve-analysis-and-its-environmental-applications

Bacterial Growth Curve Analysis and its Environmental Applications

Source: Laboratories of Dr. Ian Pepper and Dr. Charles Gerba - The University of Arizona
Demonstrating Author: Luisa Ikner
Bacteria are among the most ...

The student will investigate and understand that bacteria and viruses have an effect on living systems. Key ideas include  bacteria and viruses have a role in other organisms and the environment; and

BIO.4.d

History of Microbiology

Microbiology, a scientific field dedicated to the study of microorganisms, has undergone profound development since its inception in the 17th century. Its ...

Infection

When a pathogen enters the body and reproduces, it can cause an infection, damage body cells, and cause illness symptoms that eventually lead to disease. ...

Defense Mechanism Against Infection

Natural flora, body system defenses, and inflammation are natural barriers of the body against infectious agents regardless of previous exposure. Normal ...

The student will investigate and understand that bacteria and viruses have an effect on living systems. Key ideas include  the germ theory of infectious disease is supported by evidence.

BIO.4.e

Prophage Integration in Bacterial Cells

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