Nonhuman Primate Model to Assess Fetal Zika Virus Infection Complications

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ABSTRACT Infection with Zika virus (ZIKV) has been very recently implicated in an increase in the incidence of microcephaly in Brazil, however the actual impact of the presence of ZIKV in the fetus on neural development, including microcephaly, is poorly understood. While ongoing epidemiology will likely strengthen pregnancy outcome associations with ZIKV and possibly reveal the dynamics of maternal infection that influence pregnancy outcome, direct interrogation of factors that drive fetal outcomes will not be possible in human clinical settings. The nonhuman primate offers an outstanding opportunity to gain insight into these pathophysiological processes in fetal infection with ZIKV. Our overall goal is to establish a fetal ZIKV infection model by amniotic fluid delivery to study its effects on fetal growth and CNS development. By directly infecting the fetus with the virus, we will bypass the potential bottleneck of transplacental transmission, which may be a rate-limiting step in studying fetal outcomes, since in most circumstances the placenta prevents, and does not facilitate, transmission of pathogens to the fetus. Thus, direct introduction of the virus into the amniotic fluid will be a more efficient approach for defining pathological events directly in the fetal compartment. We propose two Specific Aims to address our goal. Specific Aim 1. To determine whether the macaque fetus is sensitive to ZIKV infection, we will bypass the potential placental barrier and directly inoculate the amniotic fluid, monitoring fetal well-being and development with virological, immunological, ultrasound and MRI analyses. Specific Aim 2. To define the ontogeny and tissue tropism of fetal infection, we will sequentially collect fetal tissues following intrauterine infection to map viral tropism and fetal pathogenesis, focusing on comprehensive fetal histopathology. The development and validation of this model will establish a rapid screen for the impact of fetal infection on the central nervous system as well as overall fetal development. Direct validation of the nonhuman primate model to study fetal neuropathology, growth restriction, and possibly fetal demise will be an incredibly valuable step forward in building the nonhuman primate platform to obtain a mechanistic understanding of the severe neuropathology seen in the outbreak in Brazil. A predictable fetal outcome will allow selective titration of the dose-related neurological impact as judged by histopathology, so that the model will also reveal more subtle neurobehavioral insults than microcephaly, likely to be an extreme outcome.