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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:
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Severe human infection.
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Fatality rate 30% (9-50%).
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No FDA or European approved vaccine or treatment.
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Transmission by tick bite or contact with
infected blood/body fluids.
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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.
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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
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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.
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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.
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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:
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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
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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
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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)
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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.
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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.
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Development of a vaccine against CCHF virus
Boost
Prime
Day
0
CCHF
Challenge
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14
21
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Analysis
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Efficacy studies
100% protection from lethal challenge
 First demonstration of CCHF
vaccine efficacy
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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.
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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
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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
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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
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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
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Development of a vaccine against CCHF virus
Summary
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CCHF is a real and growing threat – most widespread VHF across
Europe/Asia Africa.
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PHE’s vaccine candidate is promising with efficacy proof of concept in
mouse model.
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Next step is to confirm mechanism of action (passive/adoptive transfer
studies).
Development of a vaccine against CCHF virus