Disclosed herein are virus-like particle (VLP)-based monovalent vaccine compositions. The compositions may comprise a spherical retroviral Group-specific Antigen (Gag) protein core and a single Ebola glycoprotein selected from either a Zaire (EBOV) glycoprotein or a Sudan (SUDV) glycoprotein. The Ebola glycoprotein may be incorporated into the surface of the spherical Gag core, wherein said VLP-based vaccine presents a single Ebola glycoprotein antigen.

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.

The present invention relates to a virus-derived particle comprising one or more Cas protein(s), as well as to kits and methods using the same for altering a target nucleic acid.

The present invention relates to a method of quantifying the amount of Mock Virus Particles (MVP) removed from a solution as a result of processing that solution through a purification technique. This method involves the steps of adding MVP to a solution, processing the solution through a purification technique, quantifying the amount of MVP removed from the solution. The present invention also relates to a kit that can be used in conjunction with the method. This kit will comprise at least one stock solution of MVP and at least one quantification solution.

A vaccine for use in the prophylaxis and/or treatment of a disease

The present invention relates to an adenoviral vector capable of encoding a virus-like particle (VLP), said VLP displaying an inactive immune-suppressive domain (ISD). The vaccine of the invention shows an improved immune response from either of both of the response pathways initiated by CD4 T cells or CD8 T cells.