Name: how viruses infect cells and multiply
Uploaded: 2019-03-11T09:21:23.000Z
Duration: 50 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

What are Viruses?

- [내레이터] 바이러스는 고유의 유전자 물질을RNA나 DNA의 형태로 운반하여 숙주 세포 내부에침략하여 복제를 하는 구성체입니다.바이러스는 숙주 세포의 표면수용체에결합된 후 진입하여 유전물질을비코드화시키며 신속히 해체합니다.DNA 바이러스의 경우숙주 세포의 복제 단백질이 이후 바이러스단백질로 복제되고 합성되는 바이러스 유전체의새로운 복사체를 합성하도록 지시를 합니다.마침내 숙주 세포는 이들 바이러스 구성요소들을후손으로 다시 모으며 단일 바이러스 입자가 수 천개를더 생산해내도록 하고 이는 종종 숙주 세포의 소멸로이어집니다.

야마우치, 요헤이, 아리 헬레니우스. "바이러스 진입 한 눈에 보기." J Cell Sci 126, no. 6 (2013년 3월 15일): 1289–95. [<a href="https://doi.org/10.1242/jcs.119685" target="__blank">출처</a>]

Lin, Derek M, Britt Koskella, and Henry C Lin. "파지 요법: 다제내성 시대의 항생제에 대한 대안." World Journal of Gastrointestinal Pharmacology and Therapeutics 8, no. 3 (August 6, 2017): 162–73. [<a href="https://doi.org/10.4292/wjgpt.v8.i3.162" target="__blank">소스</a>]

니카이즈, 발레리. "바이러스에 대한 작물 면역: 결과 및 미래의 과제." 식물 과학의 프론티어 5 (2014년 11월 21일). [<a href="https://doi.org/10.3389/fpls.2014.00660" target="__blank">출처</a>]

바이러스란 무엇인가?

<h4>개요</h4>
 
 바이러스(virus)는 단백질 껍질에 둘러싸인 RNA 또는 DNA 유전체(genome)로 구성된 미세한 전염성 입자입니다. 바이러스는 스스로 번식할 수 없으며, 세포에 침입해서 세포 내 체계를 사용해 더 많은 바이러스를 만들 수 있습니다. 바이러스가 숙주 세포를 감염시키면 단백질 껍질을 제거하고 숙주의 세포 체계가 자신의 유전 물질을 전사(transcription)하고 번역(translation)하도록 지시합니다. 이렇게 납치된 세포는 복제된 구성요소를 수천 개의 바이러스 자손(progeny)으로 조립하는데, 이 자손은 숙주 세포를 파열시키고 죽일 수 있습니다. 이렇게 새롭게 조립된 바이러스는 더 많은 숙주 세포를 감염시킵니다.
 
 <h4>왜 바이러스를 연구합니까?</h4>
 
 바이러스는 박테리아, 식물, 동물 등 다양한 종류의 세포를 감염시킬 수 있습니다. 박테리아를 표적으로 삼는 바이러스, 즉 박테리오파지(bacteriophage, 줄여서 phage; 파지)는 매우 풍부합니다. 현재 연구는 인간의 다제내성 박테리아 감염을 치료하기 위한 파지치료요법(phage therapy)에 초점을 맞추고 있습니다. 전염병이 엄청난 농작물과 경제적 손실을 초래하기 때문에 재배된 식물을 감염시키는 바이러스 또한 많이 연구되고 있습니다.
 
 바이러스는 경제적으로 중요한 작물인 담배 식물이 담배모자이크바이러스(tobacco mosaic virus)로 알려진 신비한 질병에 시달리던 19세기에 처음 발견됐습니다. 동물 바이러스는 수의학 연구와 의학 연구 모두에서 매우 중요합니다. 또한 바이러스는 일반적인 감기, 수두, 헤르페스부터 황열병, 간염 및 천연두와 같은 더 위험한 감염에 이르기까지 많은 인간 질병의 기저에 있습니다.
 
 <h4>바이러스의 구조</h4>
 
 바이러스는 표적 세포를 공격하는 데 특화된 다양한 형태를 가지고 있습니다. 모든 바이러스의 두 가지 주요 구성 요소는 바이러스 유전체와 캡시드(capsid)로 알려진 보호 단백질 껍질(coat)입니다. 바이러스 유전체는 단일 또는 이중 가닥의 RNA 또는 DNA로 구성되어 있으며, 캡시드를 구성하는 단백질을 암호화합니다. 바이러스 유전체와 캡시드는 함께 뉴클레오캡시드(nucleocapsid)로 알려져 있습니다.
 
 여러 진핵생물(eukaryote) 바이러스의 독특한 특징은 캡시드를 둘러싸고 있는 외피(envelope)로 알려진 인지질막(phospholipid membrane)입니다. 이 외피는 일반적으로 이전에 감염된 숙주 세포의 세포막에서 유래하지만, 거기에 붙어 있는 바이러스 단백질(외피단백질(envelope protein)이라고 함)도 포함할 수 있습니다. 마지막으로, 어떤 동물 바이러스는 외피와 캡시드 사이의 공간에 바이러스 암호화 단백질의 모음인 테규먼트(tegument)을 가지고 있습니다.
 
 <h4>바이러스 감염</h4>
 
 바이러스 생활사(life cycle)는 부착(attachment), 침입(entry), 복제(replication), 조합(assembly), 방출(release), 이렇게 다섯 단계로 나눌 수 있습니다. 바이러스의 표면에 있는 단백질은 특정한 숙주 세포를 인식하도록 도와줍니다. 일부 바이러스는 이런 표면 단백질을 이용해 세포 수용체(receptor)에 결합해 내포작용(endocytosis)을 개시하는 반면, 외피 바이러스는 숙주 세포막과 직접 융합할 수 있습니다.
 
 일부 박테리오파지는 세포에 들어가지 않습니다. 대신 숙주 세포에 자신의 유전체와 바이러스 효소를 주입합니다. 일단 세포 안에 들어가면, 바이러스는 껍질을 버리고 숙주 세포의 체계가 자신의 유전체를 전사하고 번역하도록 지시합니다. 숙주 세포는 바이러스 자손을 만들기 위해 바이러스 유전체의 새로운 사본을 바이러스 입자로 포장합니다. 자손 바이러스는 세포에서 방출되기 전에 숙주 세포에 저장되거나 세포막에서 돌출하며 지속해서 세포에서 방출될 수 있습니다. 바이러스 감염 주기는 용균성(lytic) 또는 용원성(lysogenic)으로 분류됩니다. 용균 주기에선 새로운 바이러스가 숙주 세포에서 터져 나와 숙주를 죽입니다. 용원 주기에선 바이러스 DNA가 숙주 유전체에 통합되어 잠복해 있다가 숙주 세포가 복제될 때마다 같이 복제됩니다.

개요

바이러스는 단백질 껍질에 둘러싸인 RNA 또는 DNA 게놈으로 구성된 미세한 감염 입자입니다. 그것은 재생할 수 없습니다 ...

Education

교육

JoVE Core

Biology

생물학

Genetics

유전학

Viruses

바이러스

KEY TERMS AND CONCEPTS

주요 용어 및 개념

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. The released viruses can then infect other cells.

Viruses can attack bacteria, plants, and animals. Viruses that infect bacteria are called bacteriophages, or phages, and they are very abundant. Scientists also study phages as a possible therapy for multidrug-resistant bacterial infections in humans. Plant viruses matter because outbreaks can cause major crop and economic losses.

Animal viruses are important in both veterinary research and medical research. Viruses were first discovered in the 19th century during studies of tobacco plants with a mysterious disease. That disease was later identified as Tobacco mosaic virus. Viruses are also linked to many human illnesses, including the common cold, chickenpox, herpes, yellow fever, hepatitis, and smallpox.

Viruses vary in shape, but they share two main parts: the viral genome and the capsid. The genome can be single-stranded or double-stranded RNA or DNA, and it carries the instructions for making capsid proteins. The genome and capsid together form the nucleocapsid. Many eukaryotic viruses also have an envelope, which is a phospholipid membrane often taken from a host cell. Some animal viruses also contain a tegument, a layer of viral proteins between the envelope and the capsid.

A viral infection usually follows five stages: attachment, entry, replication, assembly, and release. Viral surface proteins help the virus recognize the right host cell. Some viruses bind to host receptors and enter by endocytosis, while enveloped viruses can fuse with the host cell membrane. Some bacteriophages do not enter the cell at all. They inject their genome and viral enzymes into the host cell instead.

Once inside, the virus is uncoated and directs the host cell to copy and read its genetic material. The host cell packages the new genomes into viral particles to form progeny viruses. These progeny may stay in the cell for a time or leave by budding from the cell membrane. Viral infection can be lytic or lysogenic. In the lytic cycle, new viruses burst out and kill the host cell. In the lysogenic cycle, viral DNA becomes part of the host genome, stays dormant, and is copied when the host cell divides.

How Viruses Infect Cells and Multiply

what are viruses?

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

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...

key terms and concepts

Learn how viruses enter host cells, use cellular machinery to replicate, and spread through lytic and lysogenic cycles in plants, animals, and bacteria.

How Viruses Infect Cells and Multiply | JoVE K12

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The cell cycle refers to the sequence of events occurring throughout a typical cell&#8217;s life. In eukaryotic cells, the somatic cell cycle has two ...

Interphase

The cell cycle occurs over approximately 24 hours (in a typical human cell) and in two distinct stages: interphase, which includes three phases of the ...

The Cell Cycle Control System

Positive Regulator Molecules

Inhibition of CDK Activity

S-Cdk Initiates DNA Replication

M-Cdk Drives Transition Into Mitosis

Mitogens and the Cell Cycle

Replicative Cell Senescence

Abnormal Proliferation

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Cells Coordinate Growth and Proliferation

Mitosis and Cytokinesis

In eukaryotes, the cell division cycle is divided into distinct, coordinated cellular processes that include cell growth, DNA replication/chromosome ...

Chromosome Duplication

Cohesins

Condensins

The Mitotic Spindle

Centrosome Duplication

Spindle Assembly

Attachment of Sister Chromatids

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 Viruses Infect Cells and Multiply

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