Ribonucleic acid is abbreviated as RNA. The monomer units of nucleotides of nucleic acid are made up of ribose sugar, adenine, guanine, cytosine, uracil and phosphoric acid is called RNA. In 1963 P.J. Gomatos & I. Tamm discovered the existence of double-stranded RNA molecules in Reovirus. Rice dwarf virus contains double-stranded RNA.