In order to track the assembly of murine leukemia virus (MLV), we used fluorescence microscopy to visualize particles containing Gag molecules fused to fluorescent proteins (FPs). Gag-FP chimeras budded from cells to produce fluorescent spots, which passed through the same pore-size filters and sedimented at the same velocity as authentic MLV. N-terminal myristylation of Gag-FPs was necessary for particle formation unless wild-type Gag was coexpressed. By labeling nonmyristylated Gag with yellow FP and wild-type Gag with cyan FP, we could quantitate the coincorporation of two proteins into single particles. This experiment showed that nonmyristylated Gag was incorporated into mixed particles at approximately 50% the efficiency of wild-type Gag. Mutations that inhibit Gag-Gag interactions (K. Alin and S. P. Goff, Virology 216:418-424, 1996; K. Alin and S. P. Goff, Virology 222:339-351, 1996) were then introduced into the capsid (CA) region of Gag-FPs. The mutations P150L and R119C/P133L inhibited fluorescent particle formation by these Gag-FPs, but Gag-FPs containing these mutations could be efficiently incorporated into particles when coexpressed with wild-type Gag. When these mutations were introduced into nonmyristylated Gag-FPs, no incorporation into particles in the presence of wild-type Gag was detected. These data suggest that two independent mechanisms, CA interactions and membrane association following myristylation, cooperate in MLV Gag assembly and budding.
The present study involving adenovirus-mediated gene transfer to dog eyes provides an essential basis for gene therapy treatment of uveal melanoma-bearing patients.
This present study evaluates the potential of adenovirus-mediated gene transfer (AMGT) to the prostate of normal laboratory beagles. Many morphological and histological similarities can be noted between dog and human prostate. Moreover, dogs can spontaneously develop prostate cancer with a clinical and biological outcome identical to that in man. Firstly we showed the capacity of human adenovirus to infect canine prostatic cells in vitro. Secondly, we injected transrectally in the dogs' prostates 2610 9 plaque forming units of a ®rst generation recombinant adenovirus vector harboring the reporter gene b-galactosidase (AdRSVbgal). Seven days after the adenoviral delivery, we observed expression of the transgene in both prostates, and exclusively in epithelial cells. Despite a cellular and a humoral immune response, the infusion appeared safe, since the dogs had no fever and presented no urinary symptoms. This study constitutes the ®rst evaluation of AMGT in dog prostate and provides a basis for gene therapy treatment of prostate carcinoma-bearing patients.
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