Selexis S.a.

University of Lausanne

Spinomix S.a.

Selexs S.a.

Debiopharm International, S.a.

Nicolas Mermod

Philippe Chatellard

David Calabrese

Philipp Bucher

Pierre Alain Girod

Stefania Puttini

Damien Saugy

Duc-Quang Nguyen

Markus O Imhof

Sandra Bosshard

Pierre-Olivier Duroy

Philippe Le Mercier

Amar Rida

Markus Imhof

Jacques Schrenzel

Patrice Francois

Kaja Kostyrko

Pierre-Alain Giro

Montse Buceta

Valerie Le Fourn

Deborah Ley

Niamh Harraghy

Emanuel Schmid-Siegert

Alexandre Regamey

Pierre-Alain Girod

Monique Zahn-Zabal

Vladimir Lazarevic

Lucille Pourcel

Valérie Le Fourn

Déborah Ley

Type-C endogenous retroviruses (ERVs) embedded in Chinese hamster ovary (CHO) cells were altered to modify the release of retroviral and/or retroviral-like particles in the culture supernatant. Although evidence for the infectivity of these particles is missing, their presence has raised safety concerns. 173 type-C ERV sequences that clustered into functionally conserved groups were identified. Transcripts from one type-C ERV group were identified to be full-length with intact open reading frames, and to have corresponding viral RNA genomes that were loaded into retroviral-like particles. Also, sequence analysis of the genomic RNA from viral particles indicated that they may result from few expressed ERV sequences. Disclosed herein is the disruption/alteration of the gag gene of the expressed ERV group using CRISPR-Cas9 genome editing. Comparison of CRISPR-derived mutations at the DNA and mRNA level led to the identification of a single ERV locus responsible for the release of viral RNA-loaded particles from CHO cells. Clones bearing a Gag loss-of-function mutation in this particular ERV locus showed a reduction of viral RNA-containing particles in the cell supernatant by over 250-fold. Notably, ERV mutagenesis did not compromise cell growth, cell size or recombinant protein production. Provided herein is a new strategy and cells, in particular engineered CHO cells, to mitigate potential contaminations from CHO endogenous retroviruses during biopharmaceutical manufacturing.

Characterization and inactivation of endogenous retroviruses in chinese hamster ovary cells

Disclosed are constructs and methods for expressing DNAs of interest in particular in non-primate eukaryotic host cells that display advantages with regard quantity and quality of expression including high stability of expression and, if appropriate, transport of the expression product out of the cell.

Enhanced transgene expression and processing

Disclosed are mammalian cells and mammalian cell lines that have a reduced load of remnants of past viral/retroviral infections and methods of producing and using the same.

Eukaryotic cells for protein manufacturing and methods of making them

The present invention relates to purified and isolated DNA sequences having protein production increasing activity and more specifically to the use of matrix attachment regions (MARs) for increasing protein production activity in a eukaryotic cell. Also disclosed is a method for the identification of said active regions, in particular MAR nucleotide sequences, and the use of these characterized active MAR sequences in a new multiple transfection method.

High efficiency gene transfer and expression in mammalian cells by a multiple transfection procedure of MAR sequences

A method for separating target molecules or particles from a fibrinogen containing sample comprises: (a) trapping the said target molecules or particles in a fibrin network by converting at least partially the fibrinogen contained in the sample into fibrin; (b) retracting the said fibrin network to form a fibrin clot; (c) separating the said fibrin clot from the surrounding sample medium.

Method for separating target molecules or particles from fibrinogen-containing samples including blood components

The present invention relates to compositions and methods for transfecting eukaryotic cells with nucleic acid vectors. In particular, the invention relates to the uses of Matrix Attachment Region (MAR) elements to increase stable and transient transfection efficiency.

Matrix attachment regions and methods for use thereof

The present invention provides a system for controlled transgene transcription using chimeric activator and repressor proteins functioning in a novel regulatory network. The target transgene is actively silenced in non-inducing conditions by a novel class of chimeric proteins consisting of the DNA-binding tetracycline repressor fused to distinct multimerized eukaryotic transcriptional repression domains. In the presence of a tetracycline &ldquo;inducer&rdquo;, the repressor does not bind to the promoters for both the target gene and for another regulatory gene encoding a transactivator (e.g., GAL4-VP16). Under these inducing conditions, the transactivator activates expression of the target transgene and of its own gene, in an additional autoregulatory positive feedback loop.

Potent genetic switch allowing regulated gene expression in eukaryotic cells

The present invention provides a system for controlled transgene transcription using chimeric activator and repressor proteins functioning in a novel regulatory network. The target transgene is actively silenced in non-inducing conditions by a novel class of chimeric proteins consisting of the DNA-binding tetracycline repressor fused to distinct multimerized eukaryotic transcriptional repression domains. In the presence of a tetracycline 'inducer', the repressor does not bind to the promoters for both the target gene and for another regulatory gene encoding a transactivator (e.g., GAL4-VP16). Under these inducing conditions, the transactivator activates expression of the target transgene and of its own gene, in an additional autoregulatory positive feedback loop.

Potent genetic switch allowing regulated gene expression in eukaryotic

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Buchillon, Switzerland

Nicolas Mermod