General Properties of HIV在线视频

Hello, every one.
大家好

I am Yun Su
我是

from Department of Microbiology and Immunology
来自汕头大学

Shantou University Medical College.
微生物学与免疫学教研室的苏芸老师

In the following time,
接下来

I will share with you--the basic knowledge
我会带大家一起了解

about a well-known infectious agent
获得性免疫缺陷综合征（AIDS）的

human immunodeficiency virus (HIV),
病原体即

which causes a worldwide spreading disease--acquired
人类免疫缺陷病毒的

immunodeficiency syndrome (AIDS).
相关基础知识

Now, let’s begin.
我们开始吧

Here are the learning objectives.
以下是本节课的学习目标：

After the lecture, you are expected to:
本节课结束后，希望大家能

1.Describe the biological properties of HIV
1.描述HIV的生物学性状

(including viral structures, target cell types,
（包括病毒的结构，靶细胞种类

replication cycle, etc)
复制过程等）

2.List the routes of transmission, and risk factors,
2.列举HIV 的传播途径，感染的危险因素

explain the pathogenicity of HIV infection
阐述HIV感染的致病机制

and the clinical course of AIDS;
和AIDS 的临床表现

3.Know how to apply the proper lab tests for diagnosis
3.懂得如何使用合适的实验室检查方法诊断AIDS

and formulate the comprehensive measures for treatment,
及懂得如何制定合理的防控措施

prevention and control.
和治疗方案

The retroviruses(Retroviridae) are enveloped
逆转录病毒（逆转录病毒科）为带包膜的

positive-stranded RNA viruses
单正链RNA病毒

with a unique replication cycle.
有独特的复制周期

According to the diseases they cause, target cell,
根据病毒所致疾病、靶细胞、

virion shape, and genetic complexity,
病毒颗粒形状、基因复杂度的不同，

the human retroviruses are classified into three subfamilies:
人类逆转录病毒可分为三个亚科：

Oncovirinae including human T lymphotropic viruses
肿瘤病毒亚科（包括人类嗜T细胞病毒

(HTLV-1, HTLV-2, HTLV-5),
HTLV-1, HTLV-2, HTLV-5）

Lentivirinae including HIV-1, HIV-2,
慢病毒亚科（包括HIV-1, HIV-2）

and the Spumavirinae.
以及泡沫病毒亚科

Here, we only discuss the members of HIV family.
接下来我们只讨论HIV

OK, first of all,
我们先来

let’s take a look at the general properties of HIV.
学习HIV 的基本性状

There are two species of HIV--HIV-1 and HIV-2.
HIV分两型：HIV-1和HIV-2

They have 40% differences in
它们的全病毒核苷酸序列

full-length nucleotide sequence
差异有40%

and show some various properties.
并且各有不同特性

As compared with HIV-2, HIV-1
与HIV-2相比

has relatively high infectivity and virulence,
HIV-1有更高的传染性和毒力

resulting in the global epidemic.
可导致全球流行

HIV-2 is prevalent mostly in Western Africa,
HIV-2主要在西非流行

and the disease develops much more slowly.
引发的AIDS病程发展更慢

As the picture shows, HIV is a spherical, enveloped,
如图所示，HIV呈球形，有包膜

RNA virus with a diameter of 80 to 120 nm.
直径约80-120nm

The envelope is acquired by budding
HIV通过出芽

from the plasma membrane
从宿主细胞膜获得包膜

and contains viral glycoprotein spikes.
包膜上有糖蛋白刺突

The envelope surrounds a capsid. Within the capsid,
包膜包绕着衣壳

it contains two identical copies
衣壳内有两条相同的

of the positive-stranded RNA genome.
单正链RNA基因组

The genome consists of three major genes
基因组包含3个

that encode polyproteins. Moreover,
编码多聚蛋白的主要基因

the virion also contains some enzymes
此外，病毒颗粒还含有

including reverse transcriptase,
逆转录酶

protease and integrase.
蛋白酶和整合酶

HIV undergoes a unique replication cycle
HIV具有的独特复制周期

with the reverse transcription and synthesis of provirus.
其中包括有逆转录与合成前病毒的过程

Here,
现在

we take HIV-1 as example to learn about the viral genome.
我们以HIV-1为例，学习病毒基因组

HIV-1 carries three structural genes (gag, pol, and env)
HIV-1有3个结构基因(gag, pol, env)

and six regulatory genes (tat, rev, nef, vif, vpr, and vpu).
和6个调控基因(tat, rev, nef, vif, vpr, vpu)

The three structural genes:
3个结构基因是：

Gag encodes group specific antigens
gag基因，编码组特异性抗原

(including capsid, matrix, and nucleic acid binding proteins),
（包括衣壳蛋白、基质蛋白和核衣壳蛋白）

Pol encodes polymerase, protease,
pol基因，编码逆转录酶、蛋白酶和整合酶

and integrase, and Env encodes envelope glycoproteins.
env基因，编码包膜糖蛋白

Three regulatory genes (tat, rev, and nef)
6个调控基因中，tat、 rev和 nef

encode regulatory proteins
编码控制表达的

that involve in controling expression,
调节蛋白

two (vif and vpu) encode proteins required
vif和vpu编码参与

for virion maturation,
病毒颗粒成熟的蛋白质

and one (vpr) encodes a transcriptional activator.
vpr编码转录激活因子

At each end of the genome are long terminal
基因组两端是

repeat (LTR) sequences.
长末端重复序列（LTR）

The LTR sequences include promoters, enhancers,
包含启动子、增强子

and other gene sequences relate to
以及其他

binding different cellular transcription factors.
与转录调控因子结合的基因序列

Let's look at the viral structure more in detail.
接下来我们进一步学习病毒的结构

On the surface of the virion,
你能找到病毒颗粒表面

could you find lollipop-like spikes?
像棒棒糖一样的刺突吗？

Yes, they are the glycoproteins: gp120 and gp41.
它们是包膜糖蛋白gp120和gp41

Env gene encodes polyprotein gp160.
Env基因编码多聚前体蛋白gp160

Gp120 and gp41 subunits come from the cleavage of gp160.
gp160裂解成gp120和gp41两个亚单位

The subunit gp120 is a attachment protein responsible
gp120为吸附蛋白

for binding to host cell receptors—CD4 molecule.
可与宿主细胞表面的病毒受体CD4分子结合

It can also trigger the production of neutralizing antibody.
gp120也可诱导中和抗体产生

The gp120 is extensively glycosylated and variable,
gp120高度糖基化，容易发生变异

so that it causes antigenicity drift.
因此可导致抗原性漂移

These factors impede antibody clearance of the virus
这些因素有利于病毒逃避免疫清除

and create the difficulties for an ideal vaccine development.
也为HIV疫苗的研制制造了重重困难

The subunit gp41 is a fusion protein,
亚单位gp41是融合蛋白

which promotes the viral fusion with the cell membrane.
可以促进病毒包膜与宿主细胞膜融合

As mentioned previously, gag encodes
前面提到，gag基因编码

group specific antigens including
组特异性抗原包括

capsid, matrix, and nucleic acid binding proteins.
衣壳蛋白、基质蛋白和核衣壳蛋白

Within the envelope is the viral matrix (p17) and the core,
包膜内是病毒基质蛋白（p17）和核心

or capsid (p24).
或者衣壳蛋白p24

P24 has high specificity and it could be used for diagnosis.
P24具有高度特异性，可用于诊断

What’s more,
此外

there are some other proteins binding
还有一些结合在核酸的蛋白质

to the nucleic acid like p7,p9.
如p7和p9

The pol gene encodes the three main enzymes
Pol基因编码病毒生命周期

that are required for the viral life cycle:
所必需的三种酶：

reverse transcriptase, integrase, and protease.
逆转录酶、整合酶和蛋白酶

Reverse transcriptase(RT) plays a major role
逆转录酶在合成互补负链DNA（cDNA）

in reverse transcribing
的逆转录过程中

a complementary negative-stranded DNA (cDNA).
起重要作用

RT also acts as a ribonuclease H
同时它作为核糖核酸酶H

for degradation the RNA genome.
可将RNA基因降解

Lack of proof reading, RT is very error prone.
逆转录酶因缺乏校正功能，导致碱基的错配率高

The error rate for the RT from HIV
平均每合成2000个碱基

is one error per 2000 bases.
就会出现一个错配碱基

This genetic instability is responsible for promoting
这种基因不稳定性有利于新病毒株的产生

the generation of new strains and allows immune escape.
也利于病毒逃避免疫清除

The integrase helps a cDNA copy
整合酶使cDNA整合入

incorporate into the host genome,
宿主细胞基因组中

and the protease enzyme is required to
蛋白酶裂解前体蛋白

cleave precursor proteins into many viral peptides.
从而产生多种病毒肽

Till now,
现在

let's review the structure of HIV particle again.
让我们来再次回顾HIV的结构

Could you identify the structural components of
你能够正确辨认出

HIV correctly in the schematic diagram?
HIV示意图中的各部分结构吗？

Each virion carries glycoprotein spikes composed of
每个病毒颗粒带有由gp120和gp41组成的

gp120 and gp41.
糖蛋白刺突

We know, gp41 is a fusion molecule.
gp41是融合蛋白

Gp120 is attachment protein,
gp120是吸附蛋白

interacting with the primary receptor (CD4)
可以与宿主细胞表面的主要受体（CD4）

and co-receptor on host cells.
和辅助受体相互作用

The envelope surrounds the viral matrix (p17)
包膜内是病毒基质蛋白（p17）和核心

and the core, or capsid (p24).
或者衣壳蛋白（p24）

The HIV genome consists of two copies of
HIV基因组由两条

linear ssRNA, which are associated with reverse transcriptase,
线性ssRNA组成，与逆转录酶、

protease,and integrase.
蛋白酶和整合酶密切相关

Thank you for your attention.
感谢大家的聆听