A diversity of serine phage integrases mediate site-specific recombination in mammalian cells.

This study evaluated the ability of five serine phage integrases, from phages A118, U153, Bxb1, phiFC1, and phiRV1, to mediate recombination in mammalian cells. Two types of recombination were investigated, including the ability of an integrase to mediate recombination between its own phage att sites in the context of a mammalian cell and the ability of an integrase to perform genomic integration pairing a phage att site with an endogenous mammalian sequence. We demonstrated that the A118 integrase mediated precise intra-molecular recombination of a plasmid containing its attB and attP sites at a frequency of approximately 50% in human cells.

Enhancement of plasmid-mediated gene therapy for muscular dystrophy by directed plasmid integration.

Plasmid-mediated gene therapy can restore dystrophin expression in skeletal muscle in the mdx mouse, a model of Duchenne muscular dystrophy. However, sufficient long-term expression and distribution of dystrophin remain a hurdle for translating this technology into a viable treatment for Duchenne muscular dystrophy. To improve plasmid-mediated gene therapy for muscle diseases, we studied the effects of targeted plasmid integration using a phage integrase (phiC31) that can mediate the integration of suitably modified plasmids into the mammalian genome.

Interleukin-1-mediated inhibition of cytomegalovirus replication is due to increased IFN-beta production.

Previous studies have demonstrated that the intercellular spread of cytomegalovirus (CMV) is reduced in marrow stromal cells that either secrete interleukin-1 (IL-1) or are treated with exogenous IL-1. Here, we report that IL-1-treated marrow stromal cells and fibroblasts, when infected with CMV, produce decreased amounts of infectious progeny virus. CMV-infected cells treated with IL-1 contained more interferon-beta (IFN-beta) mRNA at 24 h postinfection compared with untreated, infected cells.

Complementation of vaccinia virus lacking the double-stranded RNA-binding protein gene E3L by human cytomegalovirus.

The cellular response to viral infection often includes activation of pathways that shut off protein synthesis and thereby inhibit viral replication. In order to enable efficient replication, many viruses carry genes such as the E3L gene of vaccinia virus that counteract these host antiviral pathways. Vaccinia virus from which the E3L gene has been deleted (VVDeltaE3L) is highly sensitive to interferon and exhibits a restricted host range, replicating very inefficiently in many cell types, including human fibroblast and U373MG cells.