Integrative analysis of microRNA expression profiles in primary alveolar macrophages after infection with PRRSV strains of different virulence

Porcine Reproductive and Respiratory Syndrome Virus (PRRSV), known as the causative agent of PRRS, is considered strain variation of different virulence. A class of small regulatory RNAs, termed microRNAs (miRNAs) was associated with gene regulation at the post-transcriptional level. It has been well established that miRNAs play many complex roles during viral infections. To indentify the impact of PRRSV strains of different virulence infections on the cellular miRNAome, we chose vJX143 and vJXM100 as research objects to perform deep sequencing and construct microRNA expression profiles from PRRSV-infected primary alveolar macrophages (PAMs). The present study has revealed the common and distinct PAM miRNA signatures associated with different virulent PRRSV infections and demonstrated that the relative expression level of miR-10b could be a potential biomarker for indicating different PRRSV strains.

vJX143 (at passage 3) was a highly pathogenic PRRSV strain isolated from the serum of a dying piglet in 2006. vJXM100 was a vJX143-derived attenuated PRRSV strain from MARC-145 passages. PAMs were infected with vJX143 and vJXM100 separately and total RNA containing the miRNA species were extracted from infected and mock-infected cells. Deep sequencing was performed by BGI Tech. The data were mapped to the known miRNAs of all organisms listed in the current miRBase and Sus scrofa genome. The relative expression levels of selected miRNAs were detected by quantitative real-time PCR.

The results showed that a large and diverse group of miRNAs are expressed in three samples and that the expression of a subset of these miRNAs is altered in PRRSV infected macrophages. Twenty-eight annotated miRNAs had p values of < 0.05 and an absolute fold change ≥ 2, which indicated they were differentially expressed after vJX143 infection, while 58 miRNAs were differentially expressed after vJXM100 infection. Interestingly, miR-10b, which was proved an important regulator of many pathological processes, showed significant differentially expressed between vJX143 and vJXM100.

Our results provide a new insight into the differences of miRNAs response to different virulent PRRSV infection, and suggest a possible miRNA molecular signature associated with different PRRSV strains.

Disclosure of Interest: None Declared.