Trans-placental transmission of the respiratory syncytial virus

Abstract

Background: Respiratory syncytial virus (RSV) causes annual epidemics of respiratory disease that effects the whole population. This observation suggests RSV is able to prevent the induction of effective long term immune responses leading to poor herd immunity. U Studies demonstrating latent RSV in dendritic cells (DC) and a recent rodent study suggesting that the virus may readily cross the placenta suggest that the viru may use novel strategies to prevent an effective memory response. Unravelling this story may be vital if effective prevntative strategies are to be developed. Aim: This study aimed to identify the presence of RSV in cord blood samples to confirm RSV trans-placental transmission in humans. Methods: Human cord blood mononucleocytes (CBM) were isolated from samples collected immediately after delivery by means of venipuncture of placental vessels using Ficoll-Hypaque gradient centrifugation and cryopreserved. RNA lysis buffer containing 1% β-mecaptoethanol was added to thawed CBM cell pellets. Total RNA was extracted and used as a template for cDNA synthesis using random primers and M-MLV reverse transcriptase. The presence of RSV was measured using a commercially available TaqMan real-time PCR kit designed to detect all species of RSV on a digital droplet (dd) PCR platform. Results: RSV was identified in 9 of 15 (60%) CBM samples analysed by ddPCR Conclusions: The data supports the suggestion that human RSV may be acquired antenatally, suggesting antenatal infection may play a role in the impaired memory responses observed postnatally. Hobson L, Everard ML. Persistent of RSV in human DCs. Clin Exp Immunol 2008 Piedimonte et l. Vertical transmission of respiratory syncytial virus . PLoS One. 2013; 8: e61309.