CORDIS

The WHO has announced that Ebola is now one of the most dangerous diseases to threaten the human race on a global scale. The severity of the 2014-2015 outbreak of Ebola in Western Africa has reached historic proportions and underscores the vulnerability of populations worldwide to pathogens. Despite the promising ring vaccination approach of Merck in Congo in 2018, no vaccines or antiviral drugs are currently approved for prevention or treatment of Ebola infections in humans. However, the severity of the recent Ebola outbreak in West Africa and failure of the health care system to fully contain the infection point out the need for the rapid development of safe and effective preventive vaccines. PEVIA consortium aims to develop and to bring to the clinics (Phase Ia in Europe and Phase Ib in Africa) an innovative pan-Ebola preventive vaccine, safe and effective against multiple Ebola virus strains and readily deployable in endemic regions. PEVIA’s cutting-edge strategy is based on two complementary and synergistic approaches including: i/ a near native recombinant Ebola glycoprotein (GP)-based vaccine to generate robust anti-EBOV neutralizing antibodies and long-term humoral responses, and ii/ a long synthetic peptides (LSP) based vaccine containing multiple overlapping CD4+ and CD8+ T-cell epitopes derived from ZEbola GP and Nucleoprotein (NP), to generate strong and long-lasting cellular responses. PEVIA consortium also aims to provide innovative functional analysis tools and in vitro methods to help with preclinical and clinical development of new Ebola and Filovirus vaccine candidates as well as novel diagnostic tests that can be readily deployed in the field.

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

PEVIA’s strategy aims to improve vaccine efficacy against various strains of a mutating virus to give a long lasting protection against multiple exposures to Ebola virus. PEVIA’s vaccines are expected to overcome the issues of stability, storage, deployment and use in endemic regions for large-scale vaccination in the event of a future Ebola outbreak. PEVIA’s innovative approach and functional analysis tools thus aim to increase the readiness to respond to future outbreaks of Ebola and other filoviral hemorrhagic fevers and to expand the scientific knowledge regarding the correlates of immune protection against Ebola infections in human. PEVIA project thus expects to have a significant impact on global health, both at the individual and the public health levels. The knowledge accumulated by the consortium may further be extended to develop effective vaccines against other virus infections. Finally, PEVIA technologies will be disseminated worldwide for a better management of Ebola infections and will help to strengthen European competitiveness and industrial leadership in the field of vaccine research and innovation.