Use of reconstituted Sendai virus envelopes for fusion-mediated microinjection of double-stranded RNA: inhibition of protein synthesis in interferon-treated cells

Interaction of reconstituted Sendai viral envelopes with sperm cells: reconstituted Sendai virus envelope-induced fusion-mediated introduction of foreign material into bull sperm cells

Reconstituted Sendai virus envelopes (RSVE), i.e. membrane vesicles bearing the viral envelope glycoproteins and phospholipids, are able to fuse with bull sperm cells. This was inferred from the increase in the degree of fluorescence dequenching (DQ) obtained following incubation of fluorescently labeled (R18 labeled) RSVE with bull sperm cells and from electron microscopy studies of RSVE-sperm interaction. Only a low degree of DQ was observed, under the same conditions, with non-fusogenic fluorescently labeled RSVE. This, and electron microscopy results, show that binding and membrane fusion events occur between RSVE and sperm cells. In addition, DQ was observed following incubation of RSVE that had been pre-loaded with the self-quenched fluorochrome Calcein, with bull sperm cells, indicating fusion-mediated injection of the dye from the RSVE space into the sperm cells.

Targeting of poly(rI)-poly(rC) by fusogenic (F protein) immunoliposomes

The aim of this study is to investigate the intracellular delivery of polynucleotides by fusogenic immunoliposomes. We have studied the internalization of poly(rI)-poly(rC) (polyIC) by liposomes into murine L929 cells. The liposomes were prepared by incorporating Sendaï virus fusogenic F protein into the lipid bilayer and targeted by a monoclonal antibody (mAb) bound to the liposomes via protein A (Staphylococcus aureus). The immunoliposomes ensured a sufficient yield of polyIC internalization, which was estimated by its ability to induce antiviral activity. In the absence of RNase treatment free and encapsulated polyIC had the same inducing effect, but in the presence of nuclease only the encapsulated polyIC, and not free polyIC, maintained its antiviral effect. The fusion process making possible the internalization of polyIC was confirmed by the fact that the polyIC effect was mainly inhibited by an anti-F protein mAb which inhibited erythrocyte hemolysis by the virus.

Cellular response to double-stranded RNA

The study of double-stranded RNA (dsRNA) encompasses a variety of fields. Basic research in this area has contributed to a greater mechanistic understanding of gene induction, tumor cell growth arrest, the establishment of antiviral states, and immunomodulation. Because of the possible clinical value of these molecules, physicians are now exploring the use of synthetic dsRNA to treat patients with cancer, HIV-1 disease, and immune dysfunction. Continued studies of the mechanisms of action of dsRNA are likely to suggest an even wider scope of clinical applications.

Evaluation of reconstituted Sendai virus envelopes as intra-articular drug vectors: effects on normal and experimentally arthritic rabbit knee joints

Fusogenic vesicles reconstituted from the envelopes of Sendai virus particles were injected into rabbit knee joints (both normal and experimentally arthritic) to evaluate the in-vivo biocompatibility of these putative drug carriers. The reconstituted Sendai virus envelopes (RSVE) were greater than 80% retained within the arthritic knee joints after 24 h and studies with 125I- and fluorescein-labelled RSVE both showed association of the vesicles with the synovia of arthritic and healthy joints. However, RSVE were found to cause inflammation after intra-articular injection, as judged by joint swelling and histological assessment, and these effects were exacerbated by successive administrations. RSVE-entrapped methotrexate, whether free or conjugated to human serum albumin, was ineffective in preventing the irritancy of RSVE or in reducing the chronic inflammation in joints affected by an experimentally induced arthritis.