VOA常速英语:Dengue Severity Depends on Prior Infection, Genetic Variation

短语讲解：

1. The first infection may result in only mild symptoms, and the body produces antibodies that will protect against the particular variety that infected them.

result in导致,结果是
例句：The quarrel resulted in his mother leaving the house.
争吵导致了他母亲离家出走。
protect against保护, 保卫
例句：You need warm clothes to protect you against the cold.
你需要暖和的衣服来御寒。

2. "Those antibodies don't necessarily work against another version of the virus, and those antibodies actually help the other version of the virus to infect the cells that it wants to infect," explained researcher Matthew Henn, of the Broad Institute in Cambridge, Massachusetts.

work against对…产生不利的作用和影响
例句：Some people work against this plan.
有些人竭力反对这一计划。

3. For example, the vaccine may have to be modified to account for subtypes of the virus that dominate in a particular area.

account for说明〔解释〕…原因，证明
例句：His illness accounts for his absence.
他因为生病, 所以才缺席。