Zika Virus Infection at Different Pregnancy Stages: Anatomopathological Findings, Target Cells and Viral Persistence in Placental Tissues

Lucia de Noronha; Camila Zanluca; Marion Burger; Andreia Akemi Suzukawa; Marina Azevedo; Patricia Z. Rebutini; Iolanda Maria Novadzki; Laurina Setsuko Tanabe; Mayra Marinho Presibella; Claudia Nunes Duarte dos Santos

This report describes the evaluation of the 24 cases of ZIKV infection confirmed in pregnant women at different gestational periods (Table 1) . Serological analysis was performed in the 15 cases for which serum samples were available; nine of these cases presented with both anti-ZIKV IgM and anti-DENV IgG, and one had only anti-DENV IgG. The presence of these IgG antibodies suggests a past Flavivirus infection. None of the anti-ZIKV IgM-positive samples crossreacted in the anti-DENV IgM ELISA (Table 1, cases LRV/16 1318 cases LRV/16 , 16 1317 cases LRV/16 , 16 870, 16 1065 cases LRV/16 , 16 1068 cases LRV/16 , 16 1029 cases LRV/16 , 16 1004 . Neither ZIKV RNA nor anti-ZIKV IgM were detected in samples of amniotic fluid, newborn cerebrospinal fluid (CSF) or ocular/oral swabs in the cases described in this article. Of the five newborn serum samples available, one presented anti-ZIKV IgM, indicating transplacental infection, although no congenital disorder was observed at the time of delivery in this case (Table 1 , case LRV/16 1065). The anatomopathological findings for the FFPE placental tissue specimens are compiled in Tables 1 and 2. Of note, although our panel includes samples from women who had ZIKV infection at different stages of pregnancy, all placental samples were obtained at the time of delivery except for one, which was from a spontaneous abortion at 12 weeks of gestation (first trimester placenta, case LRV/15 572). Additional information about this case has been published (Noronha et al., 2016) . This ZIKV-positive first trimester human placental sample (LRV/15 572) exhibited chronic villitis and TORCH-like features that are shown in Table 2 and Figure 1A .