Vaccinia Virus Enzyme Shown to Chemically Bond RNA Building Blocks to DNA Primers

Moss and Rosenblum, publishing in the Journal of Virology in 1974, studied an enzyme purified from vaccinia virus (a virus related to smallpox) that adds adenine-containing RNA building blocks onto short nucleic acid chains. This is a biochemistry paper, not a medical or skin study — the model is purified virus components tested in test-tube reactions, not cells or animals.

The enzyme, called poly(A) polymerase, builds chains of polyriboadenylate, a repeating RNA unit. The researchers found its activity increased when they added certain "primer" molecules: a synthetic DNA-RNA hybrid pair called poly(dA:dT), and a synthetic RNA called poly(C). Using chemical and enzymatic tests — including breaking down the reaction products with DNA- and RNA-cutting enzymes, and tracking a radioactive phosphorus label — they showed the new RNA chains became directly, covalently bonded to these primer molecules rather than just sitting near them.

The team also found evidence, from how the enzyme behaved when passed through a DNA-binding purification column, that one single enzyme likely handles bonding to both DNA-based and RNA-based primers, though their most purified enzyme samples still separated into two distinct protein bands on a gel. The study describes enzyme chemistry only; it says nothing about effects in living organisms or any therapeutic use.