Viral Structure and Composition在线视频

Hello everyone,now let's discuss the general
大家好，现在我们开始学习病毒的

properties of viruses.
基本性状

I'm Gang XIN from Department of Microbiology and Immunology,
我是来自汕头大学医学院

Shantou University Medical College.
微生物学与免疫学教研室的辛岗老师

This chapter will cover
这一章的内容包括

general properties of viruses, such as the
病毒的基本性状，例如

structure, replication, genetics,
结构，复制方式，基因

classification of the viruses,
病毒的分类

and viral infection and host response:
病毒的感染，宿主的应答

transmission, types of infection, pathogenesis,
如传播途径、感染的类型、致病机制

and laboratory diagnosis.
和实验室诊断

The learning objectives.
学习目标是

At the end of this chapter, you should be able to
学完这一章后，希望你能够

1.Describe the structure and composition of viruses;
1.描述病毒的结构和化学组成

2.Describe general steps of viral replication and
2.描述病毒增殖的基本步骤和

compare the replication cycles of DNA & RNA viruses;
比较DNA和RNA病毒的复制周期

3.Discuss the mechanisms of viral variation;
3.讨论病毒变异的机制

4.Illustrate the different types of viral infection;
4.阐述病毒感染的不同类型

5.Characterize the effects of viral infection on cells;
5.描述病毒感染对细胞的影响

6.List at least three viruses associated
6.列出至少三种

with malignant tumors in human.
与人类恶性肿瘤有关的病毒

To reach the learning objectives,
为了达成学习目标

we need to answer all these 9 questions.
需要回答九个问题

I hope you can answer all of them yourself
希望你们可以在学习完本章后

at the end of this chapter.
独立回答以下问题

1.What are viruses?
1.什么是病毒？

2.What is the structure of a virus?
2.病毒的结构是怎么样的？

3.How do viruses replicate?
3.病毒如何复制？

4.How do viruses change their antigenicity?
4.病毒如何改变其抗原性？

5.How to classify the viruses?
5.病毒如何分类？

6.How does viral infection manifest itself?
6.病毒感染的临床表现？

7.How can viral diseases be transmitted?
7.病毒性疾病如何传播？

8.How do we confirm the diagnosis by lab test?
8.如何通过实验室检查来诊断？

9.How does our immune system fight the viruses?
9.免疫系统如何对抗病毒？

Let see the first question: what are viruses?
第一个问题，什么是病毒？

Viruses are microbes.
病毒是微生物

Viruses are the smallest infectious agents,
病毒是最小的能引起感染的物质

and contain only one kind of nucleic acid
基因组

as their genome.
只含有一种核酸

The nucleic acid is encased in a protein shell which
核酸被包裹在蛋白质壳中

maybe surrounded by a lipid-containing membrane.
这种蛋白质壳可能被含脂质的包膜包裹

The main characteristics of viruses include
病毒的主要特征包括

1.Small. Most viruses are less than 200 nm
1.体积微小，大多数病毒直径小于200纳米

and cannot be seen with a light microscope.
在光学显微镜下不可见

2.Only one kind of nucleic acid. Viruses typically
2.只含有一种核酸，通常来说，病毒只

contain either DNA or RNA but not both; however,
包含DNA或者RNA

some viral-like particles do not contain
然而，一些类病毒性的微粒不包含

any detectable nucleic acids (e.g., prions).
任何可被检测到的核酸（例如朊粒）

3.Replicate only in living cells. We can not
3.只能在活细胞中复制，在没有活细胞

cultivate virus without living cells.
的条件下不能培养病毒

4.Self-replication. This is different from the
4.自我复制，这是一种不同于细菌

replication mode of bacteria.
的复制方式

Bacteria replicate by binary fission.
细菌通过二分裂复制

Viruses require host cells for replication.
而病毒需要在宿主细胞内进行复制

Here is the diagram of a virus.
这是病毒的示意图

In the middle is the genome of virus,
中间是病毒的基因组

and it is encased by the capsid,
它被衣壳包绕

and maybe surrounded by a membrane - envelope.
有可能有包膜

Second question: What is the structure of a virus?
第二个问题：病毒的结构是怎么样的？

Here I show you the morphology of viruses.
这里展示了病毒的形态

The complete virus particle is a virion.
完整的病毒颗粒是一个病毒体

The suffix -on means body, particle.
它的后缀“-on”指的是物体，粒子

So, virion, viral particle.
所以病毒体，是病毒颗粒

Some viruses are round, some are linear,
有些病毒是圆形的，有些是线形的

and some are like bullet, and some are complex.
有些像子弹，有些则很复杂

So the shapes include sphere, bullet,
所以其形态包括球形，子弹形

line and complex, and so on.
线形和复合形等等

This is a E. coli.
这是一个大肠杆菌

Compared with the size of the E. coli,
与大肠杆菌的大小相比

the viruses are smaller.
病毒要更小

The E. coli is the bacterium,
大肠杆菌是一种细菌

and the unit of the size is micrometer.
它大小的单位是微米

Whereas the units for measurement of virion size
而病毒大小的测量单位

are nanometers (nm).
是纳米

The clinically important viruses range from 18 nm to 300 nm.
临床常见病毒大小从18纳米到300纳米不等

The viruses under electron microscope.
电子显微镜下观察病毒

SARS-Cov-2 viruses are sphere.
新冠肺炎病毒是球形的

Tobacco mosaic plant viruses are linear.
烟草花叶病毒是线形的

Bacteriophage, complex.
噬菌体是复合形的

Rabies virus, bullet.
狂犬病病毒是子弹形的

Structure:
病毒的结构

The simplest viruses consist of a genome
最简单的病毒由一个包装在蛋白保护壳内

of DNA or RNA packaged in a protective shell
的DNA或RNA的基因组组成

of protein and, for some viruses, a membrane.
有些病毒还有一层膜

Basic structure contains core and capsid.
基本结构包括核心和衣壳

In the middle is core, which is the genome,
在中间的是核心，即基因组

DNA or RNA.
DNA或RNA

The genome can be encoded by the capsid.
基因组外是衣壳

Each unit of the capsid is called a capsomere.
衣壳的每一个单位称为壳粒

The nucleic acid and capsid together
核酸与衣壳一起

are called the nucleocapsid.
统称为核衣壳

And some viruses can be surrounded by an envelope.
有些病毒被一个包膜包绕

And there are spikes on the envelope.
并且包膜上有刺突

The virion may also contain certain essential
有些病毒颗粒可能还含有某些

or accessory enzymes or other proteins to facilitate
促进细胞初始复制的必要的辅助酶

initial replication in the cell.
或者其他蛋白质

The core is the genome of the virus.
病毒的核心是病毒的基因组

Nucleic acid: DNA or RNA,
核酸只有一种，DNA或RNA

single or double stranded (ss/ds)
单链或双链（ss/ds）

RNA viruses: positive or negative (+/-).
RNA病毒有正链或负链

The RNA can be either positive sense
正链RNA（类似信使RNA，mRNA）

(like messenger RNA, mRNA) or negative sense,
或负链RNA

double stranded (+/-).
可以是双链的

Circular or linear.
圆形或线形

May be segmented or non-segmented.
可分节段的或不分节段

Give you two examples.
举两个例子

HBV: dsDNA, circular, non-segmented.
乙肝病毒：dsDNA，圆形的，不分节段的病毒

Another example, Flu virus, -ssRNA,
流感病毒，-ssRNA病毒

linear, contains 8 segments.
线形的RNA，包含8个片段

Capsid:
衣壳

Capsid is the protein shell, or coat,
衣壳是蛋白质外壳，或外层

that encloses the genome.
它包绕了基因组

Capsomeres are distinct morphological units of capsid.
壳粒是组成衣壳的单位

The arrangement of the capsomeres around
围绕核酸周围的壳粒的排列

the nucleic acid determines the symmetry of the virion.
决定了病毒体的对称性

There are three types of symmetry
病毒体有三种对称类型

1.Icosahedral symmetry. Icosahedron means 20 faces.
1.二十面体对称,意味着有20个面

The virus looks round,
圆形的

and it is most efficient structure.
这是最高效的的结构

2.Helical symmetry
2.螺旋形对称

3.Complex structures
3.复合型对称

The icosahedron is an approximation
二十面体病毒是由

of a sphere assembled from symmetric subunits,
对称的亚单位组装成的近似球体

whereas the helical structures appear as rods.
而螺旋形结构则呈现棒状

The complex forms are associated with bacteriophages.
而复合型的结构与噬菌体有关

Here is your homework.
下面是作业

Please make this icosahedron and answer
请画出这个二十面体并回答

1.How many faces of an icosahedron?
1.一个二十面体有多少个面？

2.What is a pentamer?
2.什么是五聚体？

3.How many pentamers in an icosahedron?
3.一个二十面体有多少个五聚体？

We will discuss about these when we learn picornaviruses.
等学习小RNA病毒的时候我们将讨论这些问题

In the simplest viruses,
最简单的病毒

virion consists of nucleic acid and capsid.
病毒颗粒由核酸和衣壳组成

- naked capsid virus.
裸病毒

DNA or RNA plus structural proteins and enzymes
DNA或RNA加上结构蛋白、酶

and nucleic acid binding proteins,
和核酸结合蛋白构成的病毒

are nucleocapsid, naked capsid virus.
是核衣壳，又称裸病毒

Nucleocapsid and glycoproteins and membrane together,
核衣壳、糖蛋白与膜结合在一起的病毒

are enveloped virus.
是包膜病毒

The naked virus and enveloped virus.
裸病毒和包膜病毒

Neucleocapid could be icosaheral or helical symmetry.
核衣壳可以是二十面体对称的或螺旋状对称的

Helical nucleocapsids are always enveloped for human viruses.
人类病毒，螺旋状核衣壳总是被包膜包绕

Envelope:
包膜

Envelope is a lipid-containing membrane that
包膜是一种

surrounds some viral particles.
围绕着病毒体的含有脂类的膜

Envelope is derived from host cell membranes,
包膜来源于宿主细胞膜

but modified by the inclusion of viral glycoproteins (spikes).
但被病毒糖蛋白（刺突）所修饰

Here are the examples.
这里是一些例子

The spikes on the surface of HBV.
乙型肝炎病毒表面上的刺突

Spikes of Flu virus.
流感病毒的刺突

Spikes of HIV.
艾滋病毒的刺突

Composition of viruses.
病毒的成分

We have learned the structure of viruses.
我们已经了解了病毒的结构

The capsid is mainly protein.
衣壳的主要成分是蛋白质

Core, nucleic acid.
核心的主要成分是核酸

Envelope is lipid, and spikes are glycoproteins.
包膜的主要成分是脂质，刺突的主要成分是糖蛋白

So the composition of viruses includes protein,
所以病毒的组成包括蛋白质

nucleic acid, lipid, and glycoprotein.
核酸、脂质和糖蛋白

Shapes and relative sizes of viruses.
病毒的形状和相对大小

There are DNA viruses and RNA viruses.
病毒有DNA病毒和RNA病毒

As for the DNA viruses, there are dsDNA, ssDNA,
DNA病毒，有dsDNA, ssDNA

and dsDNA with retrotranscriptase.
和含逆转录酶的dsDNA

RNA viruses, there are -ssRNA, +ssRNA,
RNA病毒，-ssRNA, +ssRNA

dsRNA and ssRNA with retrotranscriptase.
dsRNA和含逆转录酶的ssRNA

Let's take SARS-CoV-2 as an example.
以新型冠状病毒为例

SARS-CoV-2 is +ssRNA,
新型冠状病毒的核酸是+ssRNA

capsid (N protein, helical symmetry),
其衣壳（N 蛋白，螺旋状对称）

with an envelope and spikes.
带有包膜和刺突

There are two kinds of spikes,
它有两种刺突

one is spike glycoprotein (S),
一种是糖蛋白刺突(S)

another is hemaglutinin-esterase dimer (HE)
另一种是血凝素酯酶二聚体（HE）

Now is a short review time.
现在是一个简短的复习时间

Terms& definitions you should remember
以下是大家需要记住的术语和定义

1. The complete viral particle.
1. 完整的病毒颗粒

Right, is virion.
对，是病毒体

2. The protein shell, or coat,
2. 包绕核酸基因组的

that encloses the nucleic acid genome.
蛋白质外壳或外层

Yes, capsid.
对，是衣壳

3. A lipid-containing membrane that surrounds
3.一种环绕着一些病毒颗粒

some virus particles.
的含脂质膜

Right, envelope.
对，是包膜

Let’s move to the next question.
我们来谈谈下一个问题

How do viruses replicate?
病毒是如何复制的？

This is a test.
这是一个小测试

Please re-order the steps of viral self-replication.
请将病毒自我复制的步骤重新排序

There are six steps, please re-order them.
这里有六个步骤，请将它们重新排序

Penetration, biosynthesis of viral components,
穿入，病毒成分的生物合成

attachment, assembly of new viral particles,
吸附，新的病毒颗粒的装配

release and uncoating.
释放和脱壳

After you finish the re-ordering, let's have a break.
完成重新排序后，我们休息一下

We will continue to talk about self-replication of virus
下次回来的时候

when we come back next time.
我们会继续讨论病毒的自我复制