When SV40 enters a cell, it produces t antigen, which functions to trigger viral DNA replication.

当SV40病毒进入细胞时会产生T抗原，它的作用是触发病毒DNA繁殖。

youdao

Conveniently, the microRNA that targets t antigen is made late in the infectious cycle, just when t antigen is no longer essential for virus replication.

以t抗原为攻击目标的小分子rna在感染周期的最后环节才会产生，而这时t抗原已经不再是病毒繁殖的必须条件。

youdao

Unfortunately for the virus, t antigen also serves as a target for immune (t) cells, which can destroy infected cells and prevent the virus from spreading.

对于这种病毒来说不幸的是，T抗原同样也是免疫(t)细胞的攻击对象，也就是说，免疫细胞将摧毁受到感染的细胞来防止病毒进一步扩展。

youdao

The question is, "If you're naturally exposed to antigen wouldn't this happen anyway?"

她的问题是,在自然条件下,如果接触某种抗原,那么就是否就不发生二次免疫

耶鲁公开课 - 生物医学工程探索课程节选

The other part of the adaptive immune system is the cell mediated immune system and this is an immune where that doesn't involve antibodies but involves cells that are activated in response to a foreign antigen and that utilize cellular means to get rid of it.

获得性免疫系统还包括,细胞免疫,这一免疫反应不包含抗体,但包含可以被激活来应答,并清除外源抗原的免疫细胞

耶鲁公开课 - 生物医学工程探索课程节选

Now, if I was a person that was designing a vaccine and I noticed that this was the response that it got, that antibodies were produced, they reached some intermediate level, they started to fall, I would say, "Well I haven't stimulated the immune system enough, let me re-boost, let me give another dose of antigen."

现在,如果我正在研究一种疫苗,我注意到机体会对这种疫苗产生应答,也就是会产生抗体,当抗体浓度达到中等水平后,就开始下降,就可以说,疫苗对免疫系统刺激还不足,我需要提高抗原浓度,让我再把剂量再加大一倍

耶鲁公开课 - 生物医学工程探索课程节选

Pfizer's drug tremelimumab and Bristol-Myers Squibb's ipilimumab are antibodies to a protein called CTLA-4 (cytotoxic T-lymphocyte antigen-4) that acts as an emergency brake to prevent killer T cells from attacking healthy tissue.

FORBES: Targeting Melanoma

Both drugs turn off a natural brake on immune system activity called CTLA4 (cytotoxic T-lymphocyte antigen 4).

FORBES: Magazine Article

However, before the alarm can be sounded in this way, proteins on the surface of the antigen-presenting cell and the T cell must bind together in what is called a cellular handshake.

ECONOMIST: Breaching the body's defences