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?

- 病毒是一种
 
 携带自己以RNA或DNA组成的基因组物质
 
 侵入宿主细胞
 
 并在宿主细胞内复制的结构
 
 病毒与宿主细胞表面受体结合后，
 
 病毒进入并迅速分解，
 
 解开它的遗传物质
 
 如果是DNA病毒，
 
 病毒的DNA引导宿主细胞复制蛋白
 
 合成病毒基因组的新拷贝
 
 然后转录和转化
 
 转化为病毒蛋白质
 
 最后，宿主重组这些病毒成分
 
 变成后代，允许一个病毒粒子
 
 再生产上千病毒粒子
 
 通常导致宿主细胞死亡

Yamauchi、Yohei 和 Ari Helenius。"病毒进入一目了然。"J Cell Sci 126，第 6 期（2013 年 3 月 15 日）:1289-95。[<a href="https://doi.org/10.1242/jcs.119685" target="__blank">来源</a>]

Lin， Derek M， Britt Koskella， and Henry C Lin. "噬菌体疗法:多重耐药时代抗生素的替代品。"世界胃肠道药理学与治疗学杂志 8，第 3 期（2017 年 8 月 6 日）:162-73。[<a href="https://doi.org/10.4292/wjgpt.v8.i3.162" target="__blank">来源</a>]

尼凯斯，瓦莱丽。"作物对病毒的免疫力:结果和未来挑战。"植物科学前沿 5（2014 年 11 月 21 日）。[<a href="https://doi.org/10.3389/fpls.2014.00660" target="__blank">来源</a>]

什么是病毒？

“病毒是一种微小的传染性粒子，由一个包裹在蛋白质外壳中的RNA或DNA基因组组成。它不能自己繁殖：它只能通过进入一个细胞并使用它的细胞机器制造更多的病毒。当病毒感染宿主细胞时，它会除去其蛋白质外壳，并引导宿主的机器转录和翻译其遗传物质。被劫持的细胞将复制的成分组装成数千个病毒子代，这些子代可以破裂并杀死宿主细胞。新病毒接着感染更多的宿主细胞。”

<h4>为什么要研究病毒？</h4>
 
病毒可以感染不同类型的细胞：细菌、植物和动物。以细菌为目标的病毒，称为噬菌体（或噬菌体），非常丰富目前的研究主要集中在噬菌体治疗人类多重耐药细菌感染上感染栽培植物的病毒也被高度研究，因为流行病导致巨大的作物和经济损失。
 
病毒最早发现于19世纪，当时一种重要的经济作物烟草受到一种神秘疾病的困扰，后来被鉴定为烟草花叶病毒动物病毒在兽医研究和医学研究中都具有重要意义。此外，病毒是许多人类疾病的基础，从普通感冒、水痘和疱疹，到更危险的感染，如黄热病、肝炎和天花。
 
<h4>病毒的结构</h4>
 
病毒有多种形态，专门攻击目标细胞。所有病毒的两个主要组成部分是病毒基因组及其保护蛋白外壳，即衣壳病毒基因组由单链或双链RNA或DNA组成，它编码构成衣壳的蛋白质病毒基因组和衣壳一起被称为核衣壳。
 
许多真核病毒的一个独特特征是存在一种磷脂膜，称为包围衣壳的包膜。这种包膜通常起源于先前受感染的宿主细胞膜，但也可以包括附着在其上的病毒蛋白（称为包膜蛋白）最后，一些动物病毒在外壳和衣壳之间有一簇病毒编码的蛋白质，即病毒皮。
 
<h4>病毒感染</h4>
 
病毒的生命周期可分为以下五个步骤：附着、进入、复制、组装和释放。病毒表面的蛋白质帮助它识别特定的宿主细胞一些病毒利用这些表面蛋白结合宿主细胞受体，通过内吞作用启动细胞内化，而包膜病毒可以直接与宿主细胞膜融合。
 
一些噬菌体不进入细胞；它们将基因组（和病毒酶）注入宿主细胞。一旦进入细胞，病毒就没有被覆盖，并引导宿主细胞的机器转录和翻译其基因组。宿主细胞将病毒基因组的新拷贝打包成病毒颗粒，从而产生后代。子代病毒可能在释放前储存在宿主细胞中，或通过从细胞膜上出芽而不断地从细胞中挤出。病毒感染周期分为溶解性或溶原性。在裂解周期中，新病毒从宿主细胞中爆发，从而杀死宿主细胞。在溶原循环中，病毒DNA被整合到宿主基因组中，在那里它处于休眠状态，每次宿主细胞复制时都被复制。

概述

病毒是一种微小的感染性颗粒，由包裹在蛋白质外壳内的RNA或DNA基因组组成。它无法独立进行自我复制……

Education

教育

JoVE Core

Biology

生物学

Genetics

遗传学

Viruses

病毒

KEY TERMS AND CONCEPTS

关键术语与概念

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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BIO.5

BIO.5.D

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RNA Structure

Overview
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RNA Stability

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pre-mRNA Processing

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Types of RNA

Overview
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What is Gene Expression?

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Transcription

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Translation

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Ribosomes

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tRNA Activation

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Termination of Translation

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Cell Diversity

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structure-and-organization-of-smooth-muscles

Structure and Organization of Smooth Muscles

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Nervous Tissue: Glial Cells

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Heterochromatin

Lymphoid Cells and Tissues

Lymphoid cells and lymphoid tissues are the two major components of lymphoid organs.
Lymphoid cells consist of immune system cells such as B and T ...

chromatin-position-affects-gene-expression

Chromatin Position Affects Gene Expression

Chromatin is the massive complex of DNA and proteins packaged inside the nucleus. The complexity of chromatin folding and how it is packaged inside the ...

Two structural features of the DNA molecule provide a basis for the mechanisms of heredity: the four nucleotide bases and its double-stranded nature. The ...

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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Levels of Organization

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The Scientific Method

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Taxonomy

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Phylogeny

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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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Functions of Life

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Requirements for Human Life

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What is Homeostasis?

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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

Homeostatic Imbalances in Body Temperature

Hyperthermia is an umbrella term for elevated body temperature that occurs when heat production exceeds the body&#39;s ability to dissipate it.
...

Regulation of Food Intake

The hypothalamus releases peptides influencing feeding behavior.
Two hypothalamic neuronal groups participate in this process.
Neuropeptide Y (NPY) and ...

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

What is the Cell Cycle?

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Interphase

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The Cell Cycle Control System

Positive Regulator Molecules

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cells-coordinate-growth-and-proliferation

Cells Coordinate Growth and Proliferation

Mitosis and Cytokinesis

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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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