即使在感染你的时候，感冒病毒也会发生变异，而且新的病毒毒株经常出现，以至于当制药商研制出针对其中一种变异的疫苗时，血清已经过时了。

Colds mutate even while they're infecting you, and new strains pop up so often that by the time drug-makers create a vaccine against one variation, the serum is already out of date.

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他从先前的研究中得知，某些种类的精神抑郁症，像是季节性情绪紊乱(或者冬季抑郁症)，与一个叫HTR2A的血清素受体基因的某个特定变异体有关。

He knew from previous research that some forms of melancholia, such as seasonal affective disorder (or winter blues), have been linked to particular versions of a serotonin-receptor gene called HTR2A.

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然而，在拉米夫定的治疗过程中，并没有有效的血清标志物能预测变异的早期发生。

However, there is no useful serum marker that can predict early emergence of mutants during LAM therapy.

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