Attenuated and Protease-Profile Modified Sendai Virus Vectors as a New Tool for Virotherapy of Solid Tumors

Peer reviewe

Attenuated and Protease-Profile Modified Sendai Virus Vectors as a New Tool for Virotherapy of Solid Tumors

Multiple types of oncolytic viruses are currently under investigation in clinical trials. To optimize therapeutic outcomes it is believed that the plethora of different tumor types will require a diversity of different virus types. Sendai virus (SeV), a murine parainfluenza virus, displays a broad host range, enters cells within minutes and already has been applied safely as a gene transfer vector in gene therapy patients. However, SeV spreading naturally is abrogated in human cells due to a lack of virus activating proteases. To enable oncolytic applications of SeV we here engineered a set of novel recombinant vectors by a two-step approach: (i) introduction of an ubiquitously recognized cleavage-motive into SeV fusion protein now enabling continuous spreading in human tissues, and (ii) profound attenuation of these rSeV by the knockout of viral immune modulating accessory proteins. When employing human hepatoma cell lines, newly generated SeV variants now reached high titers and induced a profound tumor cell lysis. In contrast, virus release from untransformed human fibroblasts or primary human hepatocytes was found to be reduced by about three log steps in a time course experiment which enables the cumulation of kinetic differences of the distinct phases of viral replication such as primary target cell infection, target cell replication, and progeny virus particle release. In a hepatoma xenograft animal model we found a tumor-specific spreading of our novel recombinant SeV vectors without evidence of biodistribution into non-malignant tissues. In conclusion, we successfully developed novel tumor-selective oncolytic rSeV vectors, constituting a new tool for virotherapy of solid tumors being ready for further preclinical and clinical development to address distinct tumor types

Evaluation of a novel immunogenic vaccine platform based on a genome replication-deficient Sendai vector

We developed a novel vaccine platform based on a paramyxoviral, genome replication-deficient Sendai virus vector that can express heterologous genes inserted into the genome. To validate the novel approach in vivo, we generated a combined vaccine candidate against human respiratory syncytial virus (RSV) and human parainfluenza virus type 3 (PIV3). The present study compares two different methods of displaying heterologous antigens: (i) the RSV fusion (F) protein, encoded as a secretable version in an additional transcription unit, serves as an antigen only after being expressed in infected cells; (ii) PIV3 fusion (F) and hemagglutinin-neuraminidase (HN) genes, replacing Sendai counterparts in the vector genome, are also expressed as structural components on the surface of vaccine particles. The efficacy of this prototype vaccine was assessed in a mouse model after mucosal administration. The vaccine candidate was able to elicit specific mucosal, humoral and T cell-mediated immune responses against RSV and PIV3. However, PIV3 antigen display on the vaccine particles' surface induced higher antibody titers than the RSV antigen, being expressed only after cell infection. Consequently, this construct induced an adequate neutralizing antibody response only to PIV3. Finally, replicating virus particles were not detected in the lungs of immunized mice, confirming the genome stability and replication deficiency of this vaccine vector in vivo. Both factors can contribute substantially to the safety profile of vaccine candidates. In conclusion, this replication-deficient Sendai vector represents an efficient platform that can be used for vaccine developments against various viral pathogens. (C) 2013 Elsevier Ltd. All rights reserved

Evaluation of a novel immunogenic vaccine platform based on a genome replication-deficient Sendai vector.

We developed a novel vaccine platform based on a paramyxoviral, genome replication-deficient Sendaivirus vector that can express heterologous genes inserted into the genome. To validate the novel approachin vivo, we generated a combined vaccine candidate against human respiratory syncytial virus (RSV)and human parainfluenza virus type 3 (PIV3). The present study compares two different methods ofdisplaying heterologous antigens: (i) the RSV fusion (F) protein, encoded as a secretable version in anadditional transcription unit, serves as an antigen only after being expressed in infected cells; (ii) PIV3fusion (F) and hemagglutinin-neuraminidase (HN) genes, replacing Sendai counterparts in the vectorgenome, are also expressed as structural components on the surface of vaccine particles. The efficacyof this prototype vaccine was assessed in a mouse model after mucosal administration. The vaccinecandidate was able to elicit specific mucosal, humoral and T cell-mediated immune responses againstRSV and PIV3. However, PIV3 antigen display on the vaccine particles’ surface induced higher antibodytiters than the RSV antigen, being expressed only after cell infection. Consequently, this construct inducedan adequate neutralizing antibody response only to PIV3. Finally, replicating virus particles were notdetected in the lungs of immunized mice, confirming the genome stability and replication deficiencyof this vaccine vector in vivo. Both factors can contribute substantially to the safety profile of vaccinecandidates. In conclusion, this replication-deficient Sendai vector represents an efficient platform thatcan be used for vaccine developments against various viral pathogens