The effect of H1N1 vaccination on serum miRNA expression in children: a tale of caution for microRNA microarray studies

To describe vaccine associated changes in the expression of microRNAs 21 days after vaccination in children receiving one of two pandemic influenza (H1N1) vaccines. Serum samples were obtained from children aged 6 months to 12 years enrolled in an open label randomised control trial of two pandemic influenza (H1N1) vaccines, in which participants received either ASO3B adjuvanted split virion or a whole virion non-adjuvanted vaccine. 44 samples from a discovery cohort of 22 children were assayed. The microarray results revealed 19 microRNAs were differentially expressed after vaccination after adjustment for multiple testing. The microarray detected ubiquitous expression of several microRNAs which could not be validated by RT-qPCR, many of which have little evidence of existence in publicly available RNA sequencing data. Real time PCR (RT-qPCR) confirmed downregulation of miR-142-3p in the discovery cohort. These findings were not replicated in the subsequent validation cohort (n=22).