Release of particle associated RNA dependent DNA polymerases by primary chicken and quail embryo cells

These results show that primary chick embryo cells in culture release a particle bound RNA dependent DNA polymerase into the culture fluid. The enzyme is also found in the allantoic fluid of embryonated chicken eggs. This phenomenon is not restricted to the chicken system because primary quail embryo cells which are not known to express the so far known endogenous viruses release a particle bound RNA dependent DNA polymerase as well. In both cases this enzymes may be part of an hitherto unknown endogenous viral system. However, since the expression of the chicken- and quail-enzyme goes through a sharp peak during embryogenesis one may speculate on a physiological role for the newly described enzymes during development.