Manufacturing and Characterization of a Recombinant Adeno-Associated Virus Type 8 Reference Standard Material

International audienceGene therapy approaches using recombinant adeno-associated virus serotype 2 (rAAV2) and serotype 8 (rAAV8) have achieved significant clinical benefits. The generation of rAAV Reference Standard Materials (RSM) is key to providing points of reference for particle titer, vector genome titer, and infectious titer for gene transfer vectors. Following the example of the rAAV2RSM, here we have generated and characterized a novel RSM based on rAAV serotype 8. The rAAV8RSM was produced using transient transfection, and the purification was based on density gradient ultracentrifugation. The rAAV8RSM was distributed for characterization along with standard assay protocols to 16 laboratories worldwide. Mean titers and 95% confidence interval

Raver1 is an integral component of muscle contractile elements

Raver1, a ubiquitously expressed protein, was originally identified as a ligand for metavinculin, the muscle-specific isoform of the microfilament-associated protein vinculin. The protein resides primarily in the nucleus, where it colocalises and may interact with polypyrimidine-tract-binding protein, which is involved in alternative splicing processes. During skeletal muscle differentiation, raver1 translocates to the cytoplasm and eventually targets the Z-line of sarcomeres. Here, it colocalises with metavinculin, vinculin and alpha-actinin, all of which have biochemically been identified as raver1 ligands. To obtain more information about the potential role of raver1 in muscle structure and function, we have investigated its distribution and fine localisation in mouse striated and smooth muscle, by using three monoclonal antibodies that recognise epitopes in different regions of the raver1 protein. Our immunofluorescence and immunoelectron-microscopic results indicate that the cytoplasmic accumulation of raver1 is not confined to skeletal muscle but also occurs in heart and smooth muscle. Unlike vinculin and metavinculin, cytoplasmic raver1 is not restricted to costameres but additionally represents an integral part of the sarcomere. In isolated myofibrils and in ultrathin sections of skeletal muscle, raver1 has been found concentrated at the I-Z-I band. A minor fraction of raver1 is present in the nuclei of all three types of muscle. These data indicate that, during muscle differentiation, raver1 might link gene expression with structural functions of the contractile machinery of muscle