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Poly-8-bromoriboadenylic acid was synthesized by the bromination of adenosine-5'-monophosphate to yield 8-bromoadenosine-5'-monophosphate which on conversion to the 5'-diphosphate form was polymerized by polynucleotide phosphorylase (PNPase). The polymer formed a 1:1 hybrid with polyribouridylic acid and the hybrid was found to protect chick embryos against Wesselsbron virus (H10964).

Poly-5-dimethylaminouridylic acid, (poly(Me2N5U)) has been synthesized by the conversion of 5-bromouridine-5'-monophosphate to 5-dimethylaminouridine-5'-monophosphate which was later made into the 5'-diphosphate and subsequently polymerized by PNPase. The polymer formed a 1:1 hybrid with poly(A) with the ability to induce the production of interferon in chick embryoes as certain doses of the hybrid protected chick embryoes against wesselsbron virus (H 10964).

Poly(A):poly(U) (polyadenylic acid:polyuridylic acid hybrid); poly(O8A):poly(U) (poly-8-oxy-adenylic acid:polyuridylic acid hybrid); poly(A):poly(MeNH5U) (polyadenylic acid-5-methylamino uridylic acid hybrid) and poly(O8A):poly(MeNH5U) (poly-8-oxyadenylic acid:poly-5-methylamino uridylic acid hybrid) were studied in chick embryos to compare the protection offered against Semliki forest virus (the Nigerian strain) AN 49809. The modified polymers showed a higher activity index but were more toxic than the unmodified analogue.

A ribonuclease has been extracted from bat liver and purified. From polyacrylamide gel electrophoresis, it was found that there is only one molecular weight unit in this enzyme and this has a molecular weight of about 28,000. This enzyme was found to hydrolyse both purine and pyrimidine polynucleotides (e.g. polyadenylic acid and polycytidylic acid respectively). Hydrolysis of polyadenylic acid was found to be faster than that of polycytidylic acid.

Poly(8-oxyinosinic acid) (poly O8I), was synthesized by polymerizing 8-oxyinosine diphosphate using the enzyme polynucleotide phosphorylase (PNPase). The polymer formed a 1 : 1 hybrid with polycytidylic acid (poly C). The hybrid was found to induce the production of interferon in the brain of white albino mice and protected mice against Wesselsbron virus (H 10964).