A method for producing long double stranded RNA comprising; (a) purifying: - a first composition comprising a virus-like particle comprising a capsid, which capsid exhibits resistance to hydrolysis catalyzed by at least one hydrolase acting on peptide bonds when the capsids are contacted with the hydrolase and said capsid enclosing at least one heterologous cargo molecule said heterologous cargo molecule comprising a long single stranded sense RNA having more than 30 nucleotides, the cargo molecule further comprising a capsid specific packing sequence and - a second composition comprising a comprising a capsid, which capsid exhibits resistance to hydrolysis catalyzed by at least one hydrolase acting on peptide bonds when the capsids are contacted with the hydrolase and said capsid enclosing at least one heterologous cargo molecule said heterologous cargo molecule comprising an long antisense single stranded RNA complementary to the sense RNA of the first composition said antisense single stranded RNA having more than 30 nucleotides, the cargo molecule further comprising a capsid specific packing sequence, (b) mixing equal amounts of each composition; (c) isolating the heterologous cargo molecules thereof; (d) annealing the complementary heterologous cargo molecules to form a double stranded RNA molecule; (e) isolating the double stranded RNA molecule. (a) purifying: - a first composition comprising a virus-like particle comprising a capsid, which capsid exhibits resistance to hydrolysis catalyzed by at least one hydrolase acting on peptide bonds when the capsids are contacted with the hydrolase and said capsid enclosing at least one heterologous cargo molecule said heterologous cargo molecule comprising a long single stranded sense RNA having more than 30 nucleotides, the cargo molecule further comprising a capsid specific packing sequence and - a second composition comprising a comprising a capsid, which capsid exhibits resistance to hydrolysis catalyzed by at least one hydrolase acting on peptide bonds when the capsids are contacted with the hydrolase and said capsid enclosing at least one heterologous cargo molecule said heterologous cargo molecule comprising an long antisense single stranded RNA complementary to the sense RNA of the first composition said antisense single stranded RNA having more than 30 nucleotides, the cargo molecule further comprising a capsid specific packing sequence, - a first composition comprising a virus-like particle comprising a capsid, which capsid exhibits resistance to hydrolysis catalyzed by at least one hydrolase acting on peptide bonds when the capsids are contacted with the hydrolase and said capsid enclosing at least one heterologous cargo molecule said heterologous cargo molecule comprising a long single stranded sense RNA having more than 30 nucleotides, the cargo molecule further comprising a capsid specific packing sequence and - a second composition comprising a comprising a capsid, which capsid exhibits resistance to hydrolysis catalyzed by at least one hydrolase acting on peptide bonds when the capsids are contacted with the hydrolase and said capsid enclosing at least one heterologous cargo molecule said heterologous cargo molecule comprising an long antisense single stranded RNA complementary to the sense RNA of the first composition said antisense single stranded RNA having more than 30 nucleotides, the cargo molecule further comprising a capsid specific packing sequence, (b) mixing equal amounts of each composition; (c) isolating the heterologous cargo molecules thereof; (d) annealing the complementary heterologous cargo molecules to form a double stranded RNA molecule; (e) isolating the double stranded RNA molecule.