An RNA-dependent DNA polymerase, different from the known viral reverse transcriptases, in the chicken system.

The properties of an RNA-dependent DNA polymerase (an RNA-dependent DNA nucleotidyltransferase), which occurs ubiquitously in the allantoic fluid of uninfected, leukosis-virus-free eggs, are described. It is shown that the enzyme can synthesize faithful transcripts from natural RNA (globin mRNA). By biochemical and immunological methods, the enzyme can be clearly distinguished from the reverse transcriptases of the known chicken RNA tumor viruses and therefore seems to be a member of a so far unknown class of chicken polymerases.