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动物病毒如何传染到人 – 译学馆
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动物病毒如何传染到人

How do viruses jump from animals to humans? - Ben Longdon

“病毒基因的多样性超过其他所有生物基因之和”
At a Maryland country fair in 2017,
在马里兰州2017年的博览会上
the prize pigs were not looking their best.
获奖的猪看起来状态并不好
Farmers reported feverish hogs with inflamed eyes and running snouts.
农民报告说 这些发烧的猪 眼睛红肿 鼻涕直流
But while fair officials worried about the pigs,
但在展会官员担心这些猪的时候
the Maryland department of health was concerned about a group of sick fairgoers.
马里兰州卫生部门则对一组生病的参会者很关切
Some had pet the pigs,
有些人摸过这些猪
while others had merely been near their barns;
而有些人仅从猪圈旁路过
but soon, 40 of these attendees would be diagnosed with swine flu.
但不久后 这些参与者中有40人会被诊断患猪流感
More often than not, sick animals don’t infect humans.
通常情况下 生病的动物不会传染人类
But when they do, these cross-species infections,
不过一旦传染 这些跨物种感染
or viral host jumps, have the potential to produce deadly epidemics.
或叫病毒宿主转移 可能产生致命的流行病
So how can pathogens from one species infect another,
那么一个物种的病原体是如何感染另一物种的呢?
and what makes host jumps so dangerous?
是什么使宿主转移如此危险的呢?
Viruses are a type of organic parasite infecting nearly all forms of life.
病毒是一种会感染几乎所有生命形式的有机寄生物
To survive and reproduce, they must move through three stages:
为了生存和繁殖 它们必须经历三个阶段:
contact with a susceptible host, infection and replication,
与易感宿主接触 感染并复制
and transmission to other individuals.
以及传递给其他人
As an example, let’s look at human influenza.
举个例子 我们来看看人类流感
First,the flu virus encounters a new host
首先 流感病毒遇到新的宿主
and makes its way into their respiratory tract.
并进入他们的呼吸道
This isn’t so difficult, but to survive in this new body,
进入并不困难 但要在这个新的身体中生存
the virus must mount a successful infection
在病毒被免疫反应捕获并消灭前
before it’s caught and broken down by an immune response.
它必须成功感染宿主
To accomplish this task, viruses have evolved specific interactions with their host species.
为完成这项任务 病毒进化出了与宿主物种的特定互动
Human flu viruses are covered in proteins
人流感病毒覆盖着蛋白质
adapted to bind with matching receptors on human respiratory cells.
这种蛋白质可以与人类呼吸细胞上的匹配受体结合
Once inside a cell, the virus employs additional adaptations
一旦进入细胞 病毒就会采用其他适应措施
to hijack the host cell’s reproductive machinery
来劫持宿主细胞的分裂机制
and replicate its own genetic material.
并复制自己的基因物质
Now the virus only needs to
现在病毒只需
suppress or evade the host’s immune system
压制或躲避宿主的免疫系统
long enough to replicate to sufficient levels and infect more cells.
直到繁殖出足够多的基因物质并感染更多细胞
At this point,
此时
the flu can be passed on to its next victim
流感可通过任何传染性体液传播
via any transmission of infected bodily fluid.
并传递给下一个受害者
However,this simple sneeze also
然而 简单一个喷嚏
brings the virus in contact with pets, plants,
还会使病毒与宠物 植物
or even your lunch.
甚至你的午餐相接触
Viruses are constantly encountering new species and attempting to infect them.
病毒不断遇到新物种并试图感染它们
More often than not, this ends in failure.
通常情况下 这会以失败告终
In most cases, the genetic dissimilarity between the two hosts is too great.
多数情况下 两个宿主间的遗传基因差异太大
For a virus adapted to infect humans,
对于已经适应感染人类的病毒
a lettuce cell would be a foreign and inhospitable landscape.
莴苣细胞是外来的 而且是不适宜生存的环境
But there are a staggering number of viruses circulating in the environment,
但环境中传播的病毒数量惊人
all with the potential to encounter new hosts.
极有可能遇到新的宿主
And because viruses rapidly reproduce by the millions,
而且 因为病毒以数百万级迅速繁殖
they can quickly develop random mutations.
它们可以快速发生随机突变
Most mutations will have no effect, or even prove detrimental;
大多数突变都没有效果 甚至证明是有害的
but a small proportion may enable the pathogen to better infect a new species.
但一小部分变异可使病原体更容易感染新物种
The odds of winning this destructive genetic lottery increase over time,
获得这种破坏性基因的几率会随着时间的推移而增加
or if the new species is closely related to the virus’usual host.
或者新物种与病毒的常见宿主相似
For a virus adapted to another mammal,
对于适应一种哺乳动物的病毒
infecting a human might just take a few lucky mutations.
感染人类可能只需一些幸运的突变
And a virus adapted to chimpanzees,
一种适应离我们最近的
one of our closest genetic relatives, might barely require any changes at all.
遗传近亲黑猩猩的病毒 几乎不需要任何改变
It takes more than time and genetic similarity
一个宿主成功转移所需要的
for a host jump to be successful.
不仅仅是时间和基因相似性
Some viruses come equipped to easily infect a new host’s cells,
有些病毒可以轻易感染新宿主的细胞
but are then unable to evade an immune response.
但是无法逃避免疫反应
Others might have a difficult time transmitting to new hosts.
其他病毒可能较难传染到新宿主
For example, they might make the host’s blood contagious, but not their saliva.
比如 它们可能使宿主的血液 而非唾液具有传染性
However,once a host jump reaches the transmission stage,
但是 一旦宿主转移到传播阶段
the virus becomes much more dangerous.
病毒变得更加危险
Now gestating within two hosts,
现在病原体可在两个宿主中孕育
the pathogen has twice the odds of mutating into a more successful virus.
其变异为成功病毒的概率提高两倍
And each new host increases the potential for a full-blown epidemic.
且每个新宿主患全面流行病的可能也会增加
Virologists are constantly looking for mutations
病毒学家一直在寻找可能令流感类病毒
that might make viruses such as influenza more likely to jump.
更易产生宿主转移的突变
However,predicting the next potential epidemic is a major challenge.
然而 预测下一个潜在的流行病是一项重大挑战
There’s a huge diversity of viruses
病毒种类繁多
that we’re only just beginning to uncover.
我们才刚刚开始研究
Researchers are tirelessly studying the biology of these pathogens.
研究人员正在不知疲倦地研究这些病原体的生物学
And by monitoring populations to quickly identify new outbreaks,
而且通过监测人群来快速识别新的爆发
they can develop vaccines and containment protocols to stop these deadly diseases.
他们可以开发疫苗 实施控制措施来阻止这些致命的疾病

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视频概述

一个物种的病原体是如何感染另一个物种的,而且什么使宿主转移如此危险呢?

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翻译译者

甪里

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审核员 V

视频来源

https://www.youtube.com/watch?v=xjcsrU-ZmgY

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