Overview of biological effects of addition of DNA molecules to cells.

Injected DNA proceeds with certain probabilities through the following steps: degradation by serum nucleases, adsorption to cells, uptake into cells, ligation to other DNA, mutation, expression of unintegrated DNA, integration, expression of integrated DNA, and activation of or inactivation of cellular genes. The maximal probability per DNA molecule of each of these steps is estimated based on experimental results in cell culture with transfection of DNA and with infection by retroviruses. A maximum cumulative probability of having a harmful effects is calculated to be less than 10(-16) to 10(-19) per DNA molecule from a cell without activated proto-oncogenes or active viral oncogenes.

In vivo study of genetically simplified bovine leukemia virus derivatives that lack tax and rex.

Genetically simplified derivatives of complex retroviruses that replicate in animal models are useful tools to study the role of the complex regulatory genes in virus infection and pathogenesis and were proposed as a novel approach toward the development of vaccines against complex retroviruses. Previously we developed genetically simple derivatives of bovine leukemia virus (BLV) that can replicate in tissue culture independently of the BLV regulatory proteins, Tax and Rex, and the RIII and GIV open reading frames (K. Boris-Lawrie and H.

The recombination rate is not increased when retroviral RNA is missing an encapsidation sequence.

Retroviruses, as a result of the presence of two identical RNA molecules in their virions, recombine at a high rate. When nonhomologous RNA is present in the dimer RNA molecules, nonhomologous recombination occurs, although the rate is only 0.1% of the rate of homologous recombination.

Lower in vivo mutation rate of human immunodeficiency virus type 1 than that predicted from the fidelity of purified reverse transcriptase.

The level of genetic variation of human immunodeficiency virus type 1 (HIV-1), a member of the lentivirus genus of the Retroviridae family, is high relative to that of retroviruses in some other genera. The high error rates of purified HIV-1 reverse transcriptase in cell-free systems suggest an explanation for this high genetic variation. To test whether the in vivo rate of mutation during reverse transcription of HIV-1 is as high as predicted by cell-free studies, and therefore higher than that rates of mutation of retroviruses in other genera, we developed an in vivo assay for detecting forward mutations in HIV-1, using the lacZ alpha peptide gene as a reporter for mutations.