An effective Zika virus (ZIKV) vaccine will require long-term durable protection. Several ZIKV vaccine candidates have demonstrated protective efficacy in nonhuman primates, but these studies have typically involved ZIKV challenge shortly after vaccination at peak immunity. We show that a single immunization with an adenovirus vector–based vaccine, as well as two immunizations with a purified inactivated virus vaccine, afforded robust protection against ZIKV challenge in rhesus monkeys at 1 year after vaccination. In contrast, two immunizations with an optimized DNA vaccine, which provided complete protection at peak immunity, resulted in reduced protective efficacy at 1 year that was associated with declining neutralizing antibody titers to subprotective levels. These data define a microneutralization log titer of 2.0 to 2.1 as the threshold required for durable protection against ZIKV challenge in this model. Moreover, our findings demonstrate that protection against ZIKV challenge in rhesus monkeys is possible for at least 1 year with a single-shot vaccine.

有效的寨卡病毒（ZIKV）疫苗需要长期持久的保护。几种 ZIKV 候选疫苗已在非人灵长类动物中表现出保护功效，但这些研究通常涉及在免疫高峰期接种疫苗后不久进行 ZIKV 攻击。我们证明，使用基于腺病毒载体的疫苗进行单次免疫，以及使用纯化的灭活病毒疫苗进行两次免疫，在接种疫苗一年后为恒河猴提供了针对 ZIKV 攻击的强大保护。相比之下，使用优化 DNA 疫苗进行的两次免疫在免疫峰值时提供了完全保护，但在 1 年后导致保护功效降低，这与中和抗体滴度下降至亚保护水平有关。这些数据将 2.0 至 2.1 的微中和对数滴度定义为该模型中针对 ZIKV 挑战提供持久保护所需的阈值。此外，我们的研究结果表明，单次注射疫苗可以在至少 1 年时间内对恒河猴提供针对 ZIKV 攻击的保护。