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

複製の間に 遺伝物質の永久的な変化である 突然変異によっても ウイルスは遺伝的に進化します RNAが存在すると より自発的なエラーが発生します 複製には逆転写酵素が必要ですが 校正されないので 急速な進化と薬剤耐性の可能性が より高くなります これはヒト免疫不全ウイルス(HIV)に当てはまり 闘うのが非常に難しくなります

Quan, Chuansong, Weifeng Shi, Yang Yang, Yongchun Yang, Xiaoqing Liu, Wen Xu, Hong Li, et al. "New Threats from H7N9 Influenza Virus: Spread and Evolution of High- and Low-Pathogenicity Variants with High Genomic Diversity in Wave Five." Journal of Virology 92, no. 11 (2018年6月1日): e00301-18.[<a href="https://doi.org/10.1128/JVI.00301-18" target="__blank">ソース</a>]

ウイルスの突然変異

突然変異とは、ゲノム上のDNAやRNAの塩基配列が変化することです。一部の突然変異は、DNAやRNAを複製するポリメラーゼ酵素のエラーにより、ゲノムの複製中に発生します。DNAポリメラーゼとは異なり、RNAポリメラーゼには校正機能がないため、エラーが発生しやすいです。そのため、HIVのようなRNAベースのゲノムを持つウイルスは、DNAベースのゲノムを持つウイルスよりも早く変異が発生します。突然変異と組み換えが適応進化の材料となるため、RNAベースのウイルスは抗ウイルス剤に対する耐性を素早く獲得できるのです。
 
 <h4>突然変異を比較することで、進化を再構築できます</h4>
 
 現代の生物学では、ゲノム配列を比較することで進化史を明らかにすることが大きな目標です。この解析の重要な実用化例が、病気の原因となるウイルスの進化の研究です。ゲノム配列の解析が非常に迅速かつ安価になったことで、病気が発生した際のウイルスの起源や進化の過程を調べることができるようになりました。
 
 例えば、2013年に中国でH7N9と呼ばれる新型の鳥インフルエンザが発生し、人に重篤な呼吸器疾患を引き起こしました。人間と複数の鳥類から分離されたウイルスの変異を比較した結果、このインフルエンザ株の祖先は、鶏に感染する前に中国の家畜であるアヒルの集団で発生したと考えられました。この祖先株は、その後、他の鳥類ウイルスと組み合わされ、ヒトに感染したH7N9株となりました。これらの分析から、生きた家禽市場が人への感染源である可能性が高いことがわかりました。さらに、H7N9株の進化を調べる過程で、ヒトに感染する可能性のある別の鳥インフルエンザ株を発見しました。この研究は、突然変異の進化的な分析が、流行時に疫学者に重要な情報を提供できることを示しています。

突然変異とは、ゲノム内のDNAまたはRNAの塩基配列の変化です。一部の突然変異は、ゲノムの複製中に、...

Education

JoVE Core

Biology

生物学

Genetics

遺伝学

Viruses

ウイルス

KEY TERMS AND CONCEPTS

主要用語と概念

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

JoVE Core series brings biology to life through over 300 concise and easy-to-understand animated video lessons that explain key concepts in biology, plus more than 150 scientist-in-action videos that show actual research experiments conducted in today’s laboratories.

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JoVE Core シリーズは、生物学の重要な概念を説明する 300 を超える簡潔でわかりやすいアニメーション ビデオ レッスンに加え、今日の研究室で行われる実際の研究実験を示す 150 以上の科学者の活動ビデオを通じて、生物学に命を吹き込みます。

Next Generation Science Standards

Life Science

heredity-inheritance-and-variation-of-traits

Heredity: Inheritance and Variation of Traits

HS-LS3-2

Texas Essential Knowledge and Skills

BIO.5

BIO.5.D

Georgia Standards of Excellence

9-12

Entomology

SEN4.

SEN4.a

myJoVE Corporation

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Heterochromatin

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Organization of Genes

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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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Levels of Organization

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HS-LS1-2

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Negative and Positive Feedback

Homeostatic Imbalance

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pH Homeostasis

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HS-LS1-3

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Interphase

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Positive Regulator Molecules

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Cells Coordinate Growth and Proliferation

Mitosis and Cytokinesis

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Chromosome Duplication

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HS-LS1-4

How Virus Mutations Drive Outbreaks

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