Name: how virus mutations drive outbreaks
Uploaded: 2019-03-11T09:21:24.000Z
Duration: 36 s
Channel: JoVE

K12 Standards

Louisiana Student Standards for Science

High School

Life Sciences

from-molecules-to-organisms-structures-and-processes

From Molecules To Organisms: Structures And Processes

HS-LS1-8

Viral Mutations

Während der Replikation können sich Viren aufgrund von Mutationen und dauerhaften Veränderungen im genetischen Material auch genetisch entwickeln.
 Weitere spontane Fehler treten auf, wenn RNA vorhanden ist, da für die Replikation das reverses Transkriptaseenzym erforderlich ist, das nicht korrigiert wird, was zu einer höheren Wahrscheinlichkeit für eine schnelle Entwicklung und Arzneimittelresistenz führt.
 Dies ist der Fall beim humanen Immundefizienzvirus oder HIV, was die Bekämpfung so schwierig macht.

Quan, Chuansong, Weifeng Shi, Yang Yang, Yongchun Yang, Xiaoqing Liu, Wen Xu, Hong Li et al. "Neue Bedrohungen durch das H7N9-Influenzavirus: Ausbreitung und Evolution von Varianten mit hoher und niedriger Pathogenität mit hoher genomischer Vielfalt in der fünften Welle." Zeitschrift für Virologie 92, Nr. 11 (1. Juni 2018): e00301-18. [<a href="https://doi.org/10.1128/JVI.00301-18" target="__blank">Quelle</a>]

virale mutationen

Eine Mutation ist eine Veränderung der Basenabfolge von DNA oder RNA in einem Genom. Einige Mutationen treten während der Replikation des Genoms aufgrund von Fehlern der Polymerase-Enzyme auf, die die DNA oder RNA replizieren. Im Gegensatz zur DNA-Polymerase ist die RNA-Polymerase anfällig für Fehler, da sie keine korrekturlese Funktion hat. Viren mit RNA-Genomeb können daher schneller mutieren als Viren mit einem DNA-Genom. HIV besitzt beispielsweise ein RNA-Genom. Da Mutation und Rekombination das Rohmaterial für die adaptive Evolution bilden, können RNA-Viren schnell Resistenzen gegen antivirale Therapien entwickeln.
 
 <h4>Der Vergleich von Mutationen erlaubt es uns, die Evolution zu rekonstruieren</h4>
 
 Ein großes Ziel der modernen Biologie ist es, die Evolutionsgeschichte darzulegen mit Hilfe des Vergleichs von Genomsequenzen. Eine wichtige praktische Anwendung dieser Analysen ist die Untersuchung der Evolution von krankheitsverursachenden Viren. Die Genomsequenzierung ist so schnell und kostengünstig geworden, dass es heute möglich ist, die Entstehung und die laufende Evolution von Viren während eines Krankheitsausbruchs untersuchen zu können.
 
 Zum Beispiel tauchte 2013 in China ein neuer Stamm der Vogelgrippe namens H7N9 auf. Er verursachte schwere Atemwegserkrankungen beim Menschen. Durch den Vergleich der Mutationen in den aus Menschen und verschiedenen Vogelarten isolierten Viren konnten die Forscher zeigen, dass der Vorfahre dieses Grippestammes wahrscheinlich von chinesischen Hausenten stammte, bevor er an Hühner weitergegeben wurde. Dieser Stamm hat sich anschließend mit anderen Vogelviren rekombiniert, und erzeugte den H7N9-Stamm. Dieser Stamm konnte dann später auch auf den Menschen übertragen werden. Diese Analysen identifizierten als wahrscheinliche Quelle für menschliche Infektionen, die Märkte bei denen mit lebendigem Geflügel gehandelt wird. Darüber hinaus fanden die Forscher bei der Untersuchung der Evolution des H7N9-Stamms einen weiteren Stamm der Vogelgrippe, der wahrscheinlich den Menschen infizieren kann. Diese Arbeit zeigt, wie evolutionäre Analysen von Mutationen den Epidemiologen während einer Epidemie wichtige Informationen liefern können.

Virale Mutationen

Eine Mutation ist eine Veränderung in der Sequenz von DNA- oder RNA-Basen in einem Genom. Einige Mutationen treten während der Replikation des Genoms aufgrund von Fehlern auf, die von der ...

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how virus mutations drive outbreaks

Virus mutations can change how quickly a virus evolves and spreads. A mutation is a change in the sequence of bases in DNA or RNA. Some mutations happen when the genome is copied. They are caused by errors made by polymerase enzymes, which replicate DNA or RNA.

RNA viruses often change faster than DNA viruses because RNA polymerase does not proofread its work. That means RNA-based genomes, such as HIV, can gather mutations more quickly. Mutation and recombination give viruses the raw material for adaptive evolution. As a result, RNA-based viruses can sometimes evolve resistance to antiviral drugs.

Scientists also use mutations to trace how viruses evolve over time. By comparing genome sequences, researchers can reconstruct evolutionary history. This is especially useful during disease outbreaks because genome sequencing is now fast and inexpensive. It helps scientists study where a virus came from and how it is changing.

The 2013 H7N9 avian influenza outbreak in China is one example. By comparing viruses from humans and several bird species, researchers found that the ancestor likely came from domestic ducks in China before spreading to chickens. That ancestral virus later recombined with other bird viruses to form the H7N9 strain that infected humans. The analysis also pointed to live poultry markets as the likely source of human infections and revealed another avian flu strain that may also infect humans.

How Virus Mutations Drive Outbreaks

what are viruses?

How Viruses Infect Cells and Multiply

Viruses infect cells and make new copies by using a host cell’s own machinery. A virus is a tiny infectious particle with an RNA or DNA genome inside a protective protein coat. It cannot reproduce on its own, so it must enter a cell to make more viruses. After infection, the virus sheds its protein coat and uses the host cell to transcribe and translate its genetic material. The cell then assembles many new viral particles. In many cases, these new viruses rupture the host cell and kill it.

viral structure

How Virus Shapes Help Infection

Viruses have specific structures that help them infect host cells and trigger immune responses. Each virus has a core that contains either a DNA-based or RNA-based genome. That core is surrounded by a protective protein coat called the capsid. The capsid is made of smaller subunits called capsomeres. The capsid and the genome-containing core together are called the nucleocapsid. Viruses are often grouped by capsid design. Most viruses have either icosahedral or helical capsids, but some have...

lytic cycle of bacteriophages

How Phages Infect and Burst Bacteria

Bacteriophages, or phages, are viruses that infect bacteria. They have a distinctive head-tail shape. In the lytic cycle, a phage first attaches to the outside of a bacterial cell. Tail proteins bind to specific receptor proteins on the bacterium’s surface. After attachment, the phage tail injects its DNA genome into the bacterial cytoplasm. The phage then uses the bacterium’s cellular machinery to make proteins needed for replication and dispersal. When phage replication is complete, some of...

lysogenic cycle of bacteriophages

Prophage Integration in Bacteria

The lysogenic cycle shows how bacteriophages can infect bacteria without killing the host right away. In this cycle, the phage genome joins the bacterial genome. The integrated phage DNA is called a prophage, and the bacterium copies it each time it replicates. Some prophages can switch back into the lytic cycle. This change can happen after DNA damage or even without an obvious outside trigger. When the prophage is induced, the phage begins making new virus particles again. Prophages can...

retrovirus life cycles

How Retroviruses Replicate in Host Cells

Retroviruses replicate by copying their RNA genome into DNA inside a host cell. After entry, the viral enzyme reverse transcriptase makes a double-stranded DNA copy from the single-stranded RNA genome. The viral DNA is then carried into the nucleus and inserted into the host genome by integrase. Once integrated, the retroviral DNA is transcribed whenever the host genome is transcribed. This produces new viral RNA that can be copied and used again. The new RNA moves into the cytoplasm, where it...

viral recombination

How Viruses Swap Genes and Spread

Viral gene swapping can happen when more than one virus infects the same cell. After the viruses break open and expose their genomes for replication, matching regions can pair up and exchange sequences. This process is called recombination. Viruses with segmented genomes can also swap whole segments, which is called reassortment. These changes can help create new diseases. Some diseases can infect more than one species. Pigs can be infected by some human and bird viruses, along with the...

viral mutations

Virus mutations can change how quickly a virus evolves and spreads. A mutation is a change in the sequence of bases in DNA or RNA. Some mutations happen when the genome is copied. They are caused by errors made by polymerase enzymes, which replicate DNA or RNA. RNA viruses often change faster than DNA viruses because RNA polymerase does not proofread its work. That means RNA-based genomes, such as HIV, can gather mutations more quickly. Mutation and recombination give viruses the raw material...

key terms and concepts

Learn how RNA and DNA virus mutations differ, why RNA viruses evolve fast, and how genome sequencing helps track outbreaks like H7N9 influenza.

How Virus Mutations Drive Outbreaks | JoVE K12

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structure-and-organization-of-smooth-muscles

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Organization of Genes

Chromosome Structure

A functional eukaryotic chromosome must contain three elements: a centromere, telomeres, and numerous origins of replication.
The centromere is a DNA ...

Construct an explanation based on evidence for how the structure of DNA determines the structure of proteins which carry out the essential functions of life through systems of specialized cells. Emphasis is on the conceptual understanding that DNA sequences determine the amino acid sequence and thus protein structure. Students can produce scientific writing, or presentations, and/or physical models that communicate constructed explanations.

HS-LS1-1

Characteristics of Life

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The Scientific Method

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Develop and use a model to illustrate the hierarchical organization of interacting systems that provide specific functions within multicellular organisms. Emphasis is on functions at the organism system level such as nutrient uptake, water delivery, or organism movement in response to neural stimuli. An example of an interacting system could be an artery depending on the proper function of elastic tissue and smooth muscle to regulate and deliver the proper amount of blood within the circulatory system.

HS-LS1-2

Overview of Metabolism

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Regulation of Metabolism

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Positive and Negative Feedback Loops

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Negative and Positive Feedback

Homeostatic Imbalance

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pH Homeostasis

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Homeostatic Imbalances in Body Temperature

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Regulation of Food Intake

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Plan and conduct an investigation to provide evidence that feedback mechanisms maintain homeostasis in living organisms. Examples of investigations could include heart rate responses to exercise, stomate responses to moisture and temperature, root development in response to water levels, or cell response to hypertonic and hypotonic environments.

HS-LS1-3

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Mitosis and Cytokinesis

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Use a model to illustrate the role of the cell cycle and differentiation in producing and maintaining complex organisms. Emphasis is on conceptual understanding that mitosis passes on genetically identical materials via replication, not on the details of each phase in mitosis.

HS-LS1-4

How Virus Mutations Drive Outbreaks

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