Circulating microRNA profiles of Hendra virus infection in horses.

Hendra virus (HeV) is an emerging zoonotic pathogen harbored by Australian mainland flying foxes. HeV infection can cause lethal disease in humans and horses, and to date all cases of human HeV disease have resulted from contact with infected horses. Currently, diagnosis of acute HeV infections in horses relies on the productive phase of infection when virus shedding may occur. An assay that identifies infected horses during the preclinical phase of infection would reduce the risk of zoonotic viral transmission during management of HeV outbreaks. Having previously shown that the host microRNA (miR)-146a is upregulated in the blood of HeV-infected horses days prior to the detection of viremia, we have profiled miRNAs at the transcriptome-wide level to comprehensively assess differences between infected and uninfected horses. Next-generation sequencing and the miRDeep2 algorithm identified 742 mature miRNA transcripts corresponding to 593 miRNAs in whole blood of six horses (three HeV-infected, three uninfected). Thirty seven miRNAs were differentially expressed in infected horses, two of which were validated by qRT-PCR. This study describes a methodology for the transcriptome-wide profiling of miRNAs in whole blood and supports the notion that measuring host miRNA expression levels may aid infectious disease diagnosis in the future.