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The absence of an adequate animal model for studies has limited the understanding of congenital Zika syndrome (CZS) in humans during the outbreak in America. In this study, we used squirrel monkeys ( Saimiri collinsi ), a neotropical primate (which mimics the stages of human pregnancy), as a model of Zika virus (ZIKV) infection. Seven pregnant female squirrel monkeys were experimentally infected at three different gestational stages, and we were able reproduce a broad range of clinical manifestations of ZIKV lesions observed in newborn humans. Histopathological and immunohistochemical analyses of early-infected newborns (2/4) revealed damage to various areas of the brain and ZIKV antigens in the cytoplasm of neurons and glial cells, indicative of CZS. The changes caused by ZIKV infection were intrauterine developmental delay, ventriculomegaly, simplified brain gyri, vascular impairment and neuroprogenitor cell dysfunction. Our data show that the ZIKV infection outcome in squirrel monkeys is similar to that in humans, indicating that this model can be used to help answer questions about the effect of ZIKV infection on neuroembryonic development and the morphological changes induced by CZS.

During the Zika virus (ZIKV) outbreak in Brazil (2015–2016), the clinical manifestations associated with its infection were complex and included miscarriage and congenital malformations, not previously described. In this study, we evaluated the prenatal conditions of pregnant female squirrel monkeys ( Saimiri collinsi ) infected during different gestational thirds (GTs) and assessed all clinical aspects, diagnostic imaging, viremia and the immune response. In our study, 75% of the infected animals in the 1st GT group had significant clinical manifestations, such as miscarriage and prolonged viremia associated with a late immune response. Consequently, their neonates showed fetal neuropathology, such as cerebral hemorrhage, lissencephaly or malformations of the brain grooves, ventriculomegaly, and craniofacial malformations. Thus, our study demonstrated the relevance of pregnant squirrel monkeys as a model for the study of ZIKV infection in neonates due to the broad clinical manifestations presented, including the typical congenital Zika syndrome manifestations described in humans.

To investigate the association between miscarriage and ZIKV and CHIKV infection. The study population consisted of pregnant women who had miscarriages between 2015, 2016 and 2017, comprising a total of 30 women who were treated at the Santa Casa de Misericórdia do Pará Foundation (FSCMPA). The processed samples came from already paraffinized material containing placental and fetal remains, where they were tested with hematoxylin–eosin and immunohistochemistry for ZIKV and CHIKV. Regarding the sociodemographic, clinical and obstetric characteristics of the patients, they correspond to the age group between 20 and 29 years of age; of brown color; women who had abortions for the first time; miscarriages occurring in the first trimester of pregnancy; women belonging to the metropolitan region of Belém; diagnosed with incomplete abortion and who had undergone uterine curettage procedure. Regarding the histopathologic and immunohistochemical findings, an inflammatory infiltrate rich in neutrophils and lymphocytes, among others, was found in the endometrial fragments and chorionic membranes. In addition, placental areas consisting of edema, necrosis and hemorrhage were found. The study identified ZIKV and CHIKV in 40% (n = 12) of samples from spontaneous abortion specimens, and CHIKV was the most prevalent virus in the study, representing 36.11% of the total specimens, with reddish granular material in the cytoplasm of decidua cells and placental villi suggesting that the viruses may be present in these regions of the placenta.

Viruses of the Lyssavirus genus are classified into several genotypes (GT1 to GT7), of which only GT1 (classic rabies virus—RABV) has a cosmopolitan distribution and circulates in Brazil. GT1 is subdivided into several antigenic variants (AgV) maintained in independent cycles with a narrow host range and distinct geographic distributions, namely, AgV1 and AgV2 found in dogs, AgV3 in the vampire bats Desmodus rotundus , and AgV4 and AgV6 in bats non-hematophagous Tadarida brasiliensis and Lasiurus cinereus , a common variant of marmoset ( Callithrix jacchus ), and crab-eating fox ( Cerdocyon thous ). In this study, we performed phylogenetic analysis to identify at the antigenic variant level; six RABV genomes derived from the Rabies Surveillance in the north and northeast regions of Brazil. The analysis resulted in the formation of 11 monophyletic clusters, each corresponding to a particular variant, with high bootstrap support values. The samples were positioned inside the AgV3, AgV6, and Callithrix variant clades. This is the first report of the AgV6 variant found in northern Brazil, which provides valuable information for rabies surveillance in the country. The possibility of viral spillover has been much debated, as it deals with the risk of shifting transmission from a primary to a secondary host. However, more genomic surveillance studies should be performed, with a greater number and diversity of samples to better understand the transmission dynamics of each variant to detect changes in its geographic distribution and spillover events.