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Zika virus is an emerging infectious disease that is spreading rapidly through the Americas. A major concern is the association with birth defects, especially microcephaly. This report shows evidence of Zika virus in the fetal brain. ZIKV, an emerging mosquito-borne flavivirus, was initially isolated from a rhesus monkey in the Zika forest in Uganda in 1947. 1 It is transmitted by various species of aedes mosquitoes. After the first human ZIKV infection, sporadic cases were reported in Southeast Asia and sub-Saharan Africa. 2 ZIKV was responsible for the outbreak in Yap Island of Micronesia in 2007 and for major epidemics in French Polynesia, New Caledonia, the Cook Islands, and Easter Island in 2013 and 2014. 3 , 4 In 2015, there was a dramatic increase in reports of ZIKV infection in the Americas. Brazil is the most affected country, with . . .

Brazilian Zika virus causes birth defects in mice Zika virus infection has been linked to an increase in the number of infants born with microcephaly in Brazil, but direct experimental proof that Zika virus causes birth defects was lacking. Here Alysson Muotri and colleagues show that the Brazilian Zika virus strain can cross the placenta and cause intrauterine growth restriction, including signs of microcephaly, in the SJL strain of mice. They also show that the virus can infect human brain organoids, inducing cell death by apoptosis and disrupting cortical layers. Zika virus (ZIKV) is an arbovirus belonging to the genus Flavivirus (family Flaviviridae ) and was first described in 1947 in Uganda following blood analyses of sentinel Rhesus monkeys 1 . Until the twentieth century, the African and Asian lineages of the virus did not cause meaningful infections in humans. However, in 2007, vectored by Aedes aegypti mosquitoes, ZIKV caused the first noteworthy epidemic on the Yap Island in Micronesia 2 . Patients experienced fever, skin rash, arthralgia and conjunctivitis 2 . From 2013 to 2015, the Asian lineage of the virus caused further massive outbreaks in New Caledonia and French Polynesia. In 2013, ZIKV reached Brazil, later spreading to other countries in South and Central America 3 . In Brazil, the virus has been linked to congenital malformations, including microcephaly and other severe neurological diseases, such as Guillain–Barré syndrome 4 , 5 . Despite clinical evidence, direct experimental proof showing that the Brazilian ZIKV (ZIKV BR ) strain causes birth defects remains absent 6 . Here we demonstrate that ZIKV BR infects fetuses, causing intrauterine growth restriction, including signs of microcephaly, in mice. Moreover, the virus infects human cortical progenitor cells, leading to an increase in cell death. We also report that the infection of human brain organoids results in a reduction of proliferative zones and disrupted cortical layers. These results indicate that ZIKV BR crosses the placenta and causes microcephaly by targeting cortical progenitor cells, inducing cell death by apoptosis and autophagy, and impairing neurodevelopment. Our data reinforce the growing body of evidence linking the ZIKV BR outbreak to the alarming number of cases of congenital brain malformations. Our model can be used to determine the efficiency of therapeutic approaches to counteracting the harmful impact of ZIKV BR in human neurodevelopment.

The rapid spread of Zika virus (ZIKV) and its association with abnormal brain development constitute a global health emergency. Congenital ZIKV infection produces a range of mild to severe pathologies, including microcephaly. To understand the pathophysiology of ZIKV infection, we used models of the developing brain that faithfully recapitulate the tissue architecture in early to midgestation. We identify the brain cell populations that are most susceptible to ZIKV infection in primary human tissue, provide evidence for a mechanism of viral entry, and show that a commonly used antibiotic protects cultured brain cells by reducing viral proliferation. In the brain, ZIKV preferentially infected neural stem cells, astrocytes, oligodendrocyte precursor cells, and microglia, whereas neurons were less susceptible to infection. These findings suggest mechanisms for microcephaly and other pathologic features of infants with congenital ZIKV infection that are not explained by neural stem cell infection alone, such as calcifications in the cortical plate. Furthermore, we find that blocking the glia-enriched putative viral entry receptor AXL reduced ZIKV infection of astrocytes in vitro, and genetic knockdown of AXL in a glial cell line nearly abolished infection. Finally, we evaluate 2,177 compounds, focusing on drugs safe in pregnancy. We show that the macrolide antibiotic azithromycin reduced viral proliferation and virus-induced cytopathic effects in glial cell lines and human astrocytes. Our characterization of infection in the developing human brain clarifies the pathogenesis of congenital ZIKV infection and provides the basis for investigating possible therapeutic strategies to safely alleviate or prevent the most severe consequences of the epidemic.

In November, 2015, an epidemic of microcephaly was reported in Brazil, which was later attributed to congenital Zika virus infection. 7830 suspected cases had been reported to the Brazilian Ministry of Health by June 4, 2016, but little is known about their characteristics. We aimed to describe these newborn babies in terms of clinical findings, anthropometry, and survival. We reviewed all 1501 liveborn infants for whom investigation by medical teams at State level had been completed as of Feb 27, 2016, and classified suspected cases into five categories based on neuroimaging and laboratory results for Zika virus and other relevant infections. Definite cases had laboratory evidence of Zika virus infection; highly probable cases presented specific neuroimaging findings, and negative laboratory results for other congenital infections; moderately probable cases had specific imaging findings but other infections could not be ruled out; somewhat probable cases had imaging findings, but these were not reported in detail by the local teams; all other newborn babies were classified as discarded cases. Head circumference by gestational age was assessed with InterGrowth standards. First week mortality and history of rash were provided by the State medical teams. Between Nov 19, 2015, and Feb 27, 2015, investigations were completed for 1501 suspected cases reported to the Brazilian Ministry of Health, of whom 899 were discarded. Of the remainder 602 cases, 76 were definite, 54 highly probable, 181 moderately probable, and 291 somewhat probable of congenital Zika virus syndrome. Clinical, anthropometric, and survival differences were small among the four groups. Compared with these four groups, the 899 discarded cases had larger head circumferences (mean Z scores −1·54 vs −3·13, difference 1·58 [95% CI 1·45–1·72]); lower first-week mortality (14 per 1000 vs 51 per 1000; rate ratio 0·28 [95% CI 0·14–0·56]); and were less likely to have a history of rash during pregnancy (20·7% vs 61·4%, ratio 0·34 [95% CI 0·27–0·42]). Rashes in the third trimester of pregnancy were associated with brain abnormalities despite normal sized heads. One in five definite or probable cases presented head circumferences in the normal range (above −2 SD below the median of the InterGrowth standard) and for one third of definite and probable cases there was no history of a rash during pregnancy. The peak of the epidemic occurred in late November, 2015. Zika virus congenital syndrome is a new teratogenic disease. Because many definite or probable cases present normal head circumference values and their mothers do not report having a rash, screening criteria must be revised in order to detect all affected newborn babies. Brazilian Ministry of Health, Pan American Health Organization, and Wellcome Trust.

The microcephaly epidemic, which started in Brazil in 2015, was declared a Public Health Emergency of International Concern by WHO in 2016. We report the preliminary results of a case-control study investigating the association between microcephaly and Zika virus infection during pregnancy. We did this case-control study in eight public hospitals in Recife, Brazil. Cases were neonates with microcephaly. Two controls (neonates without microcephaly), matched by expected date of delivery and area of residence, were selected for each case. Serum samples of cases and controls and cerebrospinal fluid samples of cases were tested for Zika virus-specific IgM and by quantitative RT-PCR. Laboratory-confirmed Zika virus infection during pregnancy was defined as detection of Zika virus-specific IgM or a positive RT-PCR result in neonates. Maternal serum samples were tested by plaque reduction neutralisation assay for Zika virus and dengue virus. We estimated crude odds ratios (ORs) and 95% CIs using a median unbiased estimator for binary data in an unconditional logistic regression model. We estimated ORs separately for cases with and without radiological evidence of brain abnormalities. Between Jan 15, 2016, and May 2, 2016, we prospectively recruited 32 cases and 62 controls. 24 (80%) of 30 mothers of cases had Zika virus infection compared with 39 (64%) of 61 mothers of controls (p=0·12). 13 (41%) of 32 cases and none of 62 controls had laboratory-confirmed Zika virus infection; crude overall OR 55·5 (95% CI 8·6–∞); OR 113·3 (95% CI 14·5–∞) for seven cases with brain abnormalities; and OR 24·7 (95% CI 2·9–∞) for four cases without brain abnormalities. Our data suggest that the microcephaly epidemic is a result of congenital Zika virus infection. We await further data from this ongoing study to assess other potential risk factors and to confirm the strength of association in a larger sample size. Brazilian Ministry of Health, Pan American Health Organization, and Enhancing Research Activity in Epidemic Situations.

Since the emergence of Zika virus (ZIKV), reports of microcephaly have increased considerably in Brazil; however, causality between the viral epidemic and malformations in fetal brains needs further confirmation. We examined the effects of ZIKV infection in human neural stem cells growing as neurospheres and brain organoids. Using immunocytochemistry and electron microscopy, we showed that ZIKV targets human brain cells, reducing their viability and growth as neurospheres and brain organoids. These results suggest that ZIKV abrogates neurogenesis during human brain development.

New animal models of Zika virus (ZIKV) infection are imperative to accelerating efforts to treat or prevent disease in humans. Adams Waldorf et al . now report that ZIKV infection of a pregnant female pigtailed macaque caused brain lesions in the developing fetus, suggesting that this model may be useful for understanding ZIKV-associated congenital abnormalities in humans. We describe the development of fetal brain lesions after Zika virus (ZIKV) inoculation in a pregnant pigtail macaque. Periventricular lesions developed within 10 d and evolved asymmetrically in the occipital–parietal lobes. Fetal autopsy revealed ZIKV in the brain and significant cerebral white matter hypoplasia, periventricular white matter gliosis, and axonal and ependymal injury. Our observation of ZIKV-associated fetal brain lesions in a nonhuman primate provides a model for therapeutic evaluation.

Monoclonal Zika-virus-neutralizing human antibodies can protect against maternal–fetal transmission, infection and disease. Anti-Zika antibody blocks viral replication This paper reports the isolation of human monoclonal antibodies from the B cells of eight subjects who had recovered from Zika virus infection. The authors determine the immune specificity and epitope recognition patterns of the antibodies and demonstrate that one of the pan-ZIKV neutralizing antibodies, termed ZIKV-117, can protect mice both post-infection and pre-infection, and provide fetal protection in a pregnancy model. Zika virus (ZIKV) is an emerging mosquito-transmitted flavivirus that can cause severe disease, including congenital birth defects during pregnancy 1 . To develop candidate therapeutic agents against ZIKV, we isolated a panel of human monoclonal antibodies from subjects that were previously infected with ZIKV. We show that a subset of antibodies recognize diverse epitopes on the envelope (E) protein and exhibit potent neutralizing activity. One of the most inhibitory antibodies, ZIKV-117, broadly neutralized infection of ZIKV strains corresponding to African and Asian-American lineages. Epitope mapping studies revealed that ZIKV-117 recognized a unique quaternary epitope on the E protein dimer–dimer interface. We evaluated the therapeutic efficacy of ZIKV-117 in pregnant and non-pregnant mice. Monoclonal antibody treatment markedly reduced tissue pathology, placental and fetal infection, and mortality in mice. Thus, neutralizing human antibodies can protect against maternal–fetal transmission, infection and disease, and reveal important determinants for structure-based rational vaccine design efforts.

Zika virus is an arthropod-borne virus that is a member of the family Flaviviridae transmitted mainly by mosquitoes of the genus Aedes. Although usually asymptomatic, infection can result in a mild and self-limiting illness characterised by fever, rash, arthralgia, and conjunctivitis. An increase in the number of children born with microcephaly was noted in 2015 in regions of Brazil with high transmission of Zika virus. More recently, evidence has been accumulating supporting a link between Zika virus and microcephaly. Here, we describe findings from three fatal cases and two spontaneous abortions associated with Zika virus infection. In this case series, formalin-fixed paraffin-embedded tissue samples from five cases, including two newborn babies with microcephaly and severe arthrogryposis who died shortly after birth, one 2-month-old baby, and two placentas from spontaneous abortions, from Brazil were submitted to the Infectious Diseases Pathology Branch at the US Centers for Disease Control and Prevention (Atlanta, GA, USA) between December, 2015, and March, 2016. Specimens were assessed by histopathological examination, immunohistochemical assays using a mouse anti-Zika virus antibody, and RT-PCR assays targeting the NS5 and envelope genes. Amplicons of RT-PCR positive cases were sequenced for characterisation of strains. Viral antigens were localised to glial cells and neurons and associated with microcalcifications in all three fatal cases with microcephaly. Antigens were also seen in chorionic villi of one of the first trimester placentas. Tissues from all five cases were positive for Zika virus RNA by RT-PCR, and sequence analyses showed highest identities with Zika virus strains isolated from Brazil during 2015. These findings provide strong evidence of a link between Zika virus infection and different congenital central nervous system malformations, including microcephaly as well as arthrogryposis and spontaneous abortions. None.

A major concern associated with ZIKV infection is the increased incidence of microcephaly with frequent calcifications in infants born from infected mothers. To date, postmortem analysis of the central nervous system (CNS) in congenital infection is limited to individual reports or small series. We report a comprehensive neuropathological study in ten newborn babies infected with ZIKV during pregnancy, including the spinal cords and dorsal root ganglia (DRG), and also muscle, pituitaries, eye, systemic organs, and placentas. Using in situ hybridization (ISH) and electron microscopy, we investigated the role of direct viral infection in the pathogenesis of the lesions. Nine women had Zika symptoms between the 4th and 18th and one in the 28th gestational week. Two babies were born at 32, one at 34 and 36 weeks each and six at term. The cephalic perimeter was reduced in four, and normal or enlarged in six patients, although the brain weights were lower than expected. All had arthrogryposis, except the patient infected at 28 weeks gestation. We defined three patterns of CNS lesions, with different patterns of destructive, calcification, hypoplasia, and migration disturbances. Ventriculomegaly was severe in the first pattern due to midbrain damage with aqueduct stenosis/distortion. The second pattern had small brains and mild/moderate (ex-vacuo) ventriculomegaly. The third pattern, a well-formed brain with mild calcification, coincided with late infection. The absence of descending fibres resulted in hypoplastic basis pontis, pyramids, and cortico-spinal tracts. Spinal motor cell loss explained the intrauterine akinesia, arthrogryposis, and neurogenic muscle atrophy. DRG, dorsal nerve roots, and columns were normal. Lympho-histiocytic inflammation was mild. ISH showed meningeal, germinal matrix, and neocortical infection, consistent with neural progenitors death leading to proliferation and migration disorders. A secondary ischemic process may explain the destructive lesions. In conclusion, we characterized the destructive and malformative consequences of ZIKV in the nervous system, as reflected in the topography and severity of lesions, anatomic localization of the virus, and timing of infection during gestation. Our findings indicate a developmental vulnerability of the immature CNS, and shed light on possible mechanisms of brain injury of this newly recognized public health threat.