Placental Histopathology and Clinical Presentation of Severe Congenital Zika Syndrome in a Human Immunodeficiency Virus-Exposed Uninfected Infant

Abstract

In the large Zika virus (ZIKV) epidemic that occurred in Brazil in 2015, the intrauterine fetal exposure to ZIKV was associated with a significant risk of developing microcephaly and neurological disorders in the infected infants. ZIKV-associated disease has since been reported in 24 countries in the Americas. At present, definitive evidence is lacking regarding the intrauterine co-exposure to ZIKV and other viral infections and whether the coinfection impacts the risk of acquiring either infection or disease severity. Here, we provide evidence of intrauterine exposure to both ZIKV and human immunodeficiency virus (HIV) infections, causing congenital Zika syndrome in an HIV-exposed uninfected infant. Clinical, imaging and laboratory examinations of the pregnant woman and the newborn were performed. Histopathology, ZIKV/HIV-specific immunoassays, and ultrastructural evaluation of the placenta were performed. The Zika-asymptomatic, HIV-positive pregnant woman underwent ultrasounds revealing fetal cerebral ventriculomegaly, microcephaly, and brain atrophy. Her baby girl was born small for gestational age and with the neurological sequelae of congenital Zika syndrome. The evaluation of the abnormally large term placenta revealed severe damage to the maternal decidua and chorionic villi, cells positive for ZIKV-specific antigens but not for HIV antigens, and intracellular membranous clusters of virus-like particles approximately 25 nm in diameter. The rapid progression and severity of the congenital Zika syndrome may be related to the uncontrolled HIV disease in the mother. The poor inflammatory response observed in the placenta may have reduced the inherent risk of mother-to-child transmission of HIV.

Keywords: Zika virus; congenital Zika syndrome; histopathology; human immunodeficiency virus; microcephaly; placenta.

Figure 1

Cranial computed tomography (CT) images of the baby born after Zika virus infection in pregnancy. (A) Sagittal localizer CT image of the markedly abnormal skull shape, (B) axial CT images showing microcephaly, cerebral atrophy, and multiple dense intracranial periventricular calcifications located in the subcortical white matter at the gray matter–white matter interface, and (C) ocular calcification.

Figure 2

Histopathological analysis of the placenta. (A–C) Placenta of a non-ZIKV patient stained with H&E and presenting normal features: maternal decidua (Dec), decidual cells (DC), chorionic villi (CV), syncytiotrophoblasts (STB), cytotrophoblasts (CTB), extracellular matrix (EM), and blood vessels (BV). (D–J,N) Sections of ZIKV-infected placental tissue stained with H&E, showing abnormalities in the decidua, including edema (E), fibrosis (F), fibrinoid necrosis (FN), mononuclear inflammatory infiltrate (Inf), macrophages (Mø), endothelial thickening (Th), cellular degeneration [arrowhead in panel (D)], calcification (Ca), and other pathological features in CV, such as perivascular inflammatory infiltrate (PInf), vascular congestion (VC), hemorrhage (He), and inordinate proliferative STB [arrowheads in panel (N)]. (K) Placental sections from a non-ZIKV and (L) a ZIKV-infected patient stained with PAS, evidencing highlighting the EM. (M) The percent EM area was quantified in both cases; asterisks indicate statistically significant differences between samples: *P < 0.05. (O) Immunofluorescence analysis of proliferating cell nuclear antigen expression in the STB of a ZIKV-infected and (P) a non-ZIKV patient.

Figure 3

Detection of ZIKV in the placenta. (A,D,E) The E and NS1 antigens of ZIKV were not detected by immunohistochemistry in the control placenta. (B,C) Detection of ZIKV E protein in decidual cells (DC) by immunohistochemistry in the infected placenta. (F–H) The NS1 protein of ZIKV was also detected by immunochemistry in the endothelium (En), DC, syncytiotrophoblasts (STB), cytotrophoblasts (CTB), and Hofbauer cells (Hf). (I,J) Co-localization by immunofluorescence of the NS1 protein (fluorescent green) and CD11b for identification of leukocytes (fluorescent red). Nuclei were stained using DAPI (fluorescent blue). (I) ZIKV NS1 antigen was not detected in the control placenta. (J) Cells presenting dual staining (green and red) were observed in the ZIKV-infected placenta.

Figure 4

Electron microscopy analysis of ultrathin placental sections showed virus-like particles. (A–C) Electron microscopy of ultrathin sections of one non-ZIKV case exhibited regular endothelial cells (En), syncytiotrophoblasts (STB), and CTB organelles, such as mitochondria (M) and endoplasmic reticulum (ER). (D–F) Electron micrographs of ZIKV-infected placenta showing thickening of the basement membrane (Th) of the endothelium (En), dispersed chromatin in syncytiotrophoblast nuclei (N) gathered in the vicinity of the nuclear membrane, and rarefied cytoplasm with absent organelles (arrowhead); mitochondria (M) in cytotrophoblasts were smaller, with fewer cristae, and the ER exhibited dilated cisterns. (G) Cytotrophoblast of a ZIKV-infected patient with a cluster of virions in the cytoplasm. (H) In the same area, at a higher magnitude, we observed these virus-like particles located near disrupted ER. (I) Measurement using the scale bar showed that the particles have a diameter of approximately 25 nm, consistent with ZIKV.