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Open Access Research article

Reduced Dicer expression in the cord blood of infants admitted with severe respiratory syncytial virus disease

Christopher S Inchley12*, Tonje Sonerud13, Hans O Fjærli12 and Britt Nakstad12

Author Affiliations

1 Department of Pediatrics, Akershus University Hospital, Lørenskog, Norway

2 Institute of Clinical Medicine, Akershus University Hospital, University of Oslo, Lørenskog, Norway

3 EpiGen Institute, Akershus University hospital, Lørenskog, Norway

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BMC Infectious Diseases 2011, 11:59  doi:10.1186/1471-2334-11-59

Published: 8 March 2011

Abstract

Background

Respiratory syncytial virus (RSV) is one of the most important causes of pediatric hospital admissions in the developed world. The ribonuclease Dicer is an important regulator of gene expression and cellular function via RNA interference, and may also have anti-viral functions. A previous microarray analysis of the cord blood of 5 patients with RSV disease suggested downregulation of Dicer. In order to further investigate whether reduced Dicer expression can predispose newborns to RSV disease, we have analyzed the gene expression of Dicer in the cord blood of 37 infants with confirmed RSV disease.

Methods

The cord blood of 2108 newborns was collected. 51 had a positive nasopharyngeal aspirate for RSV <1 year, and were grouped according to disease severity. 37 had sufficient cord blood RNA of good quality. Dicer gene expression was assessed by qPCR analysis of cord blood using a TaqMan low-density array and compared to control infants who did not present with RSV disease using the Mann-Whitney test.

Results

There was significant downregulation of Dicer in the severe disease group: relative quantity 0.69 (95% CI: 0.56 - 0.87), p = 0.002. There was no significant downregulation in the mild disease group.

Conclusions

We demonstrate reduced Dicer expression in the cord blood of infants with severe RSV disease, prior to RSV exposure. We theorize that this may predispose to RSV disease by disruption of leukocyte gene regulation or direct anti-viral RNA interference mechanisms.