Purification and characterization of particles containing RNA-dependent DNA polymerase, in the allantoic fluid of uninfected leukosis virus-free chicken eggs.

The allantoic fluid of embryonated chicken eggs regularly contains particle-associated RNA-dependent DNA polymerase, as shown by its reaction with homopolymeric and heteropolymeric RNA and by the characterization of the products. The purification of the particles is described. The purified particles are different from the known avian RNA tumor viruses in their protein composition and their sedimentation constant. They do not exhibit biological properties typical for RNA tumour viruses, such as helper activity, interfering properties or infectivity and do not show endogenous DNA synthesis. The particles are discussed as non-viral elements.