RNA Viruses: RNA Roles in Pathogenesis, Coreplication and Viral Load

Poltronieri, Palmiro; Sun, Binlian; Mallardo, Massimo

Considering tumour-associated viruses (oncoviruses), it is estimated that 20% of all cancers are linked to infectious agents. Studies of oncogenic DNA viruses have contributed to the understanding of key molecular mechanisms of tumorigenesis and viral oncogenicity [10] . Virally encoded oncoproteins such as adenovirus E1A and human papillomavirus (HPV) E7 can bind an array of cellular proteins to override proliferation arrest. Adenovirus VA1 noncoding RNA can inhibit small interfering RNA and microRNA biogenesis, both by inhibiting nuclear export of shRNA or pre-miRNA precursors, competing for the Exportin 5 nuclear export factor, and inhibiting Dicer function by direct binding to Dicer [10] . Recently, many viral-encoded miRNAs have been discovered, especially abundant in viruses transcribed from double-stranded DNA genomes. Several virus-encoded miRNAs have unique aspects to their biogenesis, such as the location within the precursor transcript.