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Development of a vaccine candidate against CrimeanCongo Haemorrhagic Fever (CCHF) virus Dr Stuart Dowall Project Team Leader Virology and Pathogenesis group Background Crimean-Congo Haemorrhagic Fever (CCHF) virus: • Severe human infection. • Fatality rate 30% (9-50%). • No FDA or European approved vaccine or treatment. • Transmission by tick bite or contact with infected blood/body fluids. • 2 ACDP hazard group 4 pathogen. Preclinical development the PHE CCHF vaccine Development of a vaccineofagainst CCHF virus PHE pipeline fund PLF 1516/108/MR Why is it important to PHE? 1. Spread of vector across Europe. 3 Development of a vaccine against CCHF virus 2. Increased incidence in tourism areas. Why is it important to PHE? 3. Threat is national and international 4. Increases PHE international profile 4 Development of a vaccine against CCHF virus 5. Threat to armed forces. Why is it important to PHE? 6. Potential bioweapon 7. Maintain emergency response capability so expertise available. • Negative sense RNA genome giving high rate of mutations. • Segmented genome allows genetic reassortment of viruses. • Existence of an animal reservoir. • Highly pathogenic (requiring Containment Level 4 facilities). • Large risk of nosocomial spread within hospitals. 5 Development of a vaccine against CCHF virus Lack of treatments against CCHF No vaccines or antiviral drugs are approved for CCHF by FDA or EMA. Bulgarian vaccine candidate has major disadvantages: • Requires live CCHF virus • Crude preparation (non-standardised homogenisation of mouse brain) • No efficacy studies, no interest to generate data package since 70s • Is not acceptable to FDA/MHRA/EMA approval Alternative approach badly needed for a modern CCHF vaccine that can meet regulatory approval and is proven to be effective. 6 Development of a vaccine against CCHF virus Development of the vaccine candidate Our approach: We have used Modified Vaccinia Ankara (MVA) as a viral vector to induce immune responses against an inserted CCHF protein antigen. Properties of MVA that make it attractive: • • • • • • • Human safety history: >100,000 doses in 1970s with no adverse effects. Human cells non-permissive. Induction of humoral and cellular immunity. Industrial GMP established. Thermostable. Production of recombinant proteins. Clear commercial opportunities • Vaxgene, Baxter, Bavarian Nordic, Emergent all in clinical trials with MVA-based vaccines. • Approximately extra 100,000 people vaccinated with no adverse signs. • Inexpensive, low cost approach 7 Development of a vaccine against CCHF virus Development of the vaccine candidate Antigen sequence Glycoprotein GFP for selection of recombinant viruses L R N-terminal tPA for secretion & Nab induction L C-terminal V5 for in vitro antibody recognition R Transfer plasmid L R MVA genome MVA L 8 Development of a vaccine against CCHF virus R MVA permissive cell GFP+ plaque purification Confirmation of antigen expression Anti-V5 antibody (expected size of GP-V5 fusion protein = 76.6kDa, positive control protein = 62kDa) 9 Development of a vaccine against CCHF virus Anti-CCHF rabbit polyclonal sera (similar post-translational cleavages in MVA-GP to native protein) The vaccine induces cellular immunity… IFN-g ELISPOT assay Media Solid bars = 129Sv/Ev mice; hatched bars = A129 mice Summed antigen responses Individual peptide pools Similar responses in 129Sv/Ev and A129 mice were detected. Immunogenicity was not evenly distributed across the antigen. Responses were specific to the glycoprotein, and similar between mouse strains. 10 Development of a vaccine against CCHF virus GP peptides …and humoral immunity. ELISA studies Western blot The MVA-GP vaccine induced significant CCHF glycoprotein-specific antibodies. 11 Development of a vaccine against CCHF virus Boost Prime Day 0 CCHF Challenge 7 14 21 28 Analysis 35 42 Efficacy studies 100% protection from lethal challenge First demonstration of CCHF vaccine efficacy 12 Development of a vaccine against CCHF virus Viral loads RT-PCR for CCHFv gene expression (normalised to mouse HPRT gene expression). Blood Spleen Liver Day 32 = 4 days post-challenge Day 42 = 14 days post-challenge (end of study) Viral load was significantly lower in MVA-GP vaccinated mice than in control groups. 13 Development of a vaccine against CCHF virus Spleen Liver Histology H&E staining MVA-1974 Immunised A129 mice, 4 days post-challenge Marked lymphocyte loss with prominent apoptotic bodies, and infiltration by macrophages. Marked, multifocally extensive hepatocyte necrosis (arrows). A single infiltration of macrophages in the white pulp (asterisk) (scored minimal). Scattered, multifocal areas of hepatocellular necrosis with a mixed inflammatory cell infiltrate (arrows) (scored moderate). MVA-GP 14 Development of a vaccine against CCHF virus Spleen Liver Histology Immunostaining MVA-1974 Immunised A129 mice, 4 days post-challenge A few, scattered cells with cytoplasmic staining within the parenchyma. Frequent, diffuse, positively stained hepatocytes. Normal parenchyma. A few, positively stained cells within an inflammatory cell focus. MVA-GP 15 Development of a vaccine against CCHF virus Next steps Isolate splenocytes (T-cells) and sera (antibody) from immunised mice Immunise mice with MVA-GP Adoptively transfer splenocytes into naïve mice Passively transfer sera into naïve mice Challenge with CCHF virus Determine survival effects 16 Development of a vaccine against CCHF virus Market sizing Market Segment $M/Annum Adult 6.0 Travel 7.6 Military (Range) 19.5 - 43.5 Total 33.1 – 57.1 • CCHF represents a niche market • Main opportunity in military based on a range of between $33.1 – $57.1 million • Market only likely to be capable of supporting a single manufacturer and heavily reliant on military 17 Development of a vaccine against CCHF virus Summary 18 • CCHF is a real and growing threat – most widespread VHF across Europe/Asia Africa. • PHE’s vaccine candidate is promising with efficacy proof of concept in mouse model. • Next step is to confirm mechanism of action (passive/adoptive transfer studies). Development of a vaccine against CCHF virus