Since PEVIA kick-off meeting (Paris-October 4th, 2017), major achievements have been made by the PEVIA Consortium, as described below:
WP1: Partner 3 (ExcellGene Pr F. Wurm) and Partner 5 (CHUV Pr F. Spertini) developed and provided numerous Ebola GP protein variants for evaluation by partners. The screening efforts with initially 16 different molecular structures were done with GP1/2 preparations purified via His-tag affinity chromatography. Analytical work indicated a strong preference for constructs that assemble the protein monomers into CHO secreted molecular trimers. Additional structures, without His-tags, verified the superiority of trimer-based molecules and one was chosen for stable cell line and process development. Clonal recombinant cell lines were established from over 650 candidates. Two highly producing CHO cell lines are being prepared for cGMP-based Master Cell Bank generation.
WP2: Partner 4.1 (CEA Team 1-Dr B. Maillere) and Partner 10 (VAXEAL-Dr A. Bouzidi & Dr J. Kerzerho) have taken an important step in the identification of new relevant promiscuous CD4 and CD8 T-cell epitopes in ZEBOV GP and NP for the design of optimal pan-Ebola LSP-based vaccine candidates for pre-clinical and clinical studies. Using HLA-peptide binding prediction programs, they first screened the entire sequences of the ZEBOV GP and NP, leading to the selection and lab scale synthesis of two libraries of peptides predicted to contain potential promiscuous CD4 and CD8 T-cell epitopes covering a large array of HLA molecules present in both Caucasian and African populations. New CD4 and CD8 T-cell epitopes in ZEBOV GP and NP were identified and were ranked on the basis of their responder frequency and T cell response intensity. A selection of the CD4 and CD8 T cell epitopes was used to design the NP and GP sets of long synthetic peptides (LSP)
WP3: Partner 6 (IPMC–Dr F. Anjuère) has successfully selected the optimal mouse strain for immunological studies. In the same time, partner 6 has also contributed together with Partners 4 (CEA-Team 2) and 5 (CHUV) to the selection of the optimal recombinant GP antigen, among several monomeric and trimeric antigens produced by Partner 3 (ExcellGene). Using the best recombinant GP antigen provided by Partner 3 (ExcellGene) and mouse strain specific NP- and GP-based LSP designed by Partner 4 (CEA, Team 1) and provided by Partner 10 (Vaxeal), Partner 6 has also performed the in vivo studies for the selection of the optimal adjuvant for GP-based and LSP-based vaccine candidates for preclinical studies. In parallel, Partner 14 (ISS-Dr Eliana Coccia) has started in vitro studies to validate the best adjuvant for human studies.
WP4: Partner 6 (IPMC–Dr F. Anjuère) has successfully developed standardized ELISpot B assays for the detection of GP-specific antibody secreting cells (ASC) of IgG and IgA isotypes induced by GP-Ebola vaccine candidates. Partner 3 (ExcellGene–WP1) provided the trimeric mutant GP antigen selected and partner 7 (Oligovax) provided GLP batches of its adjuvant) for in vivo pre-clinical studies.
WP5: Partner 4.2 (CEA-Team 2–Dr L. Bellanger) and Partner 9 (CHRU Lille–Dr D. Hober). Based on previous upstream process (USP) optimization, Partner 4.2 produced the first purified and characterized batches of retroviral pseudotypes expressing the envelope glycoprotein of four different subtypes of Ebola. Thereafter, Partner 4.2 scaled up production of ZEBOV pseudotypes to Cell Factory (CF). Partner 9 has developed the bioassay for detecting anti-EBOV enhancing antibodies in mouse system. Using these original tools, Partner 4.2 and Partner 9 have already evaluated the neutralizing and enhancing activity of immune sera provided by Partner 6, and thus contributed to the selection of the best adjuvanted antigens.
WP6: Partner 8 (BNITM–Dr C. Munoz) The laboratory mouse, main model for immunology studies, is resistant to filovirus infection. To circumvent this problem, mouse-adapted Ebola virus (EBOV) strains or immunodeficient mice are used for EBOV pathogenesis studies. These models are not adapted to PEVIA goals due to the poor recapitulation of human disease (mouse-adapted EBOV) and the lack of competent immunity (immunodeficient mice), respectively. The BNITM team has developed and evaluated two mouse models susceptible to wild-type EBOV yet retaining immune competence.
WP10: Partner 10 (VAXEAL–Dr A. Bouzidi & Dr J. Kerzerho) and Partner 1 (AP-HP–Pr O. Launay) have successfully managed the technical, financial and administrative aspects of the PEVIA project.
Two Consortium Meetings were held in Roma (November 2018 and June 2019).
