RNA and Protein Determinants Mediate Differential Binding of miRNAs by a Viral Suppressor of RNA Silencing Thus Modulating Antiviral Immune Responses in Plants.

Many plant viruses express suppressor proteins (VSRs) that can inhibit RNA silencing, a central component of antiviral plant immunity. The most common activity of VSRs is the high-affinity binding of virus-derived siRNAs and thus their sequestration from the silencing process. Since siRNAs share large homologies with miRNAs, VSRs like the p19 may also bind miRNAs and in this way modulate cellular gene expression at the post-transcriptional level.

Antiviral Drug Targets of Single-Stranded RNA Viruses Causing Chronic Human Diseases.

Ribonucleic acid (RNA) viruses associated with chronic diseases in humans are major threats to public health causing high mortality globally. The high mutation rate of RNA viruses helps them to escape the immune response and also is responsible for the development of drug resistance. Chronic infections caused by human immunodeficiency virus (HIV) and hepatitis viruses (HBV and HCV) lead to acquired immunodeficiency syndrome (AIDS) and hepatocellular carcinoma respectively, which are one of the major causes of human deaths.

A Viral Suppressor Modulates the Plant Immune Response Early in Infection by Regulating MicroRNA Activity.

Many viral suppressors (VSRs) counteract antiviral RNA silencing, a central component of the plant's immune response by sequestration of virus-derived antiviral small interfering RNAs (siRNAs). Here, we addressed how VSRs affect the activities of cellular microRNAs (miRNAs) during a viral infection by characterizing the interactions of two unrelated VSRs, the p19 and the 2b, with miRNA 162 (miR162), miR168, and miR403. These miRNAs regulate the expression of the important silencing factors Dicer-like protein 1 (DCL1) and Argonaute proteins 1 and 2 (AGO1 and AGO2), respectively.