View Abstract

A2855 - Respiratory Syncytial Virus Infects Placental Cells and Villus Explants In Vitro
Author Block: V. Bokun1, T. J. Harford1, F. Rezaee2, F. Esper3, B. Yen-Lieberman1, J. J. Moore4, G. Piedimonte2; 1Cleveland Clinic Lerner Research Institute, Cleveland, OH, United States, 2Pediatrics, Cleveland Clinic, Cleveland, OH, United States, 3Pediatrics, Cleveland Clinic Children's, Cleveland, OH, United States, 4MetroHealth Medical Center, Cleveland, OH, United States.
RATIONALE:
Respiratory Syncytial Virus (RSV) infects most infants by the age of two, often causing severe symptoms requiring hospitalization. Using a rat model, we have previously demonstrated modulated neurotrophic pathways of developing fetal lungs and elevated postnatal airway hyper-reactivity in response to vertically transmitted RSV. Additionally, a recently published case report describing respiratory distress syndrome in a newborn with confirmed RSV at birth warrants an investigation of whether placenta could be an extra—pulmonary infection site and therefore a route of vertical transmission of RSV in humans. In this study, we aimed to investigate whether RSV can invade and replicate in choriocarcinoma (BeWo) cells, placental villus explants, and placental macrophages (Hofbauer cells).
METHODS:
Human choriocarcinoma cells (BeWo) were obtained from ATCC and infected with RSV-A2 expressing the red fluorescent protein (rrRSV), allowing for visualization of ongoing infection using fluorescence microscopy. Viral RNA expression was analyzed by qRT-PCR. Using placental tissues obtained after elective caesarean sections, placental villus explants and placental macrophage (Hofbauer) cells were isolated and cultured. Hofbauer cells were then infected with RSV at an MOI of 1.0, whereas villus explants were infected with 1.0x10^6 PFU per one explant (2mmx2mmx2mm). Levels of RSV viral RNA over a time course were assessed by qRT-PCR. Infected villus explant homogenates and Hofbauer cell supernatants were added to naïve cells to test whether infection can be transmitted by viable viral particles.
RESULTS:
Choriocarcinoma cells were infected with rrRSV in a time- and dose-dependent manner, as evidenced by increasing production of RFP and viral RNA expression, as well as transmission of infectivity to naïve cells. Analysis of RSV viral RNA expression within placental villus explants revealed a steady expression over a time-course of 3 days. Hofbauer cells also supported replication of the virus, as evidenced by increasing fluorescence and viral RNA expression. Both the supernatant of the infected tissue homogenate, and Hofbauer cell supernatants transmitted infection onto naïve epithelial cells successfully, indicating presence of viable virus. Additionally, the cells exhibited marked cytopathic effect with syncytia formation upon RSV infection.
CONCLUSION:
Our data provide evidence that placental tissues and cells could be a target of RSV after maternal viremia, and therefore a possible route to the developing fetus.