Viruses with Ambisense RNA Genomes

Abstract

Viruses are grouped on the basis of the type of their genetic information (RNA or DNA), its form (single-stranded, or double-stranded), and the procedures employed for virus replication [1]. A variety of strategies of replication are used by viruses to reproduce in cells. For the single-stranded RNA genome viruses (other than members of the Retroviridae which have a DNA intermediate in the replication cycle), the strategy involves either (a) the synthesis of proteins by translation of the viral RNA (and in some cases derivatives of that sequence that are made during the replication process), i.e., the viral-sense RNAs function as mRNA species (positive-stranded viruses); or (b) the transcription of viral-complementary mRNA species from the genome, i.e., viral RNAs do not function as mRNA species (negative-stranded viruses). For all the negative-stranded viruses, the synthesis of mRNA species at the onset of infection is achieved by viral-coded enzymes that are present in the infecting virus particles. Double-stranded RNA viruses (e.g., members of the Reoviridae) also use a virion polymerase to copy into mRNA one strand of each duplex of genomic RNA.