Authors: Lauren Woolfe, Future Science Group
Respiratory syncytial virus (RSV) can cause transient viremia and extrapulmonary dissemination, and recently the virus has been identified in fetal cord blood, suggesting it could be acquired in utero. Using Zika as an example, in this study researchers attempted to demonstrate whether RSV can cross the placental barrier.
Researchers from the Lerner Research Institute and MetroHealth Medical Center (both OH, USA), used donated placentas to isolate three major cell lines: cytotrophoblasts, stoma fibroblasts and Hofbauer cells (HBCs).
The research, published in PLoS ONE, explains how these cells were infected with recombinant RSV, which had been tagged with red fluorescent protein, and analyzed by fluorescence microscopy, Western blot and quantitative PCR.
The team determined that both fibroblasts and HBCs supported RSV replication, while cytotrophoblast cells expressed viral glycoprotein and supported limited viral replication.
“These cells don’t die when they’re infected by the virus, which is the problem” commented corresponding author Giovanni Piedimonte (Lerner Research Institute). “When they move into the fetus, they are like bombs packed with virus. They don’t disseminate the virus around by exploding, which is the typical way, but rather transfer the virus through intercellular channels.”
The researchers used multiplex cytokine assays and ELISA to determine that within the supernatant of infected HBCs, there was a significant increase in Th1 pro-inflammatory cytokines. The team therefore suggests that RSV impact the fetus not only by direct invasion but also by the production of inflammatory mediators..
“This is the first evidence that a common cold virus can infect the human placenta,” stated Piedimonte. “It supports our theory that when a woman develops a cold during pregnancy, the virus causing the maternal infection can spread to the fetus and cause a pulmonary infection even before birth.”
The researchers also suggest this exposure to RSV infection may increase the risk of the fetus developing childhood asthma.
Armed with this new knowledge on RSV vertical transmission, the team believe that this research may provide new strategies to develop prophylactic and therapeutic interventions, which could limit the potential neonatal complications from placental RSV exposure.
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Sources: Bokun V, Moore JJ, Moore R et al. Respiratory syncytial virus exhibits differential tropism for distinct human placental cell types with Hofbauer cells acting as a permissive reservoir for infection. PLOS ONE. 14(12), e0225767 (2019); https://news.tulane.edu/news/study-finds-common-cold-virus-can-infect-placenta