Dr Stuart Dowall

Project Team Leader

Virology and Pathogenesis group

Development of a vaccine candidate against Crimean-Congo Haemorrhagic Fever (CCHF)

virus

Background

Preclinical development of the PHE CCHF vaccine PHE pipeline fund PLF 1516/108/MR

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.

• ACDP hazard group 4 pathogen.

2 Development of a vaccine against CCHF virus

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1. Spread of vector across Europe. 2. Increased incidence in tourism areas.

Why is it important to PHE?

Development of a vaccine against CCHF virus

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3. Threat is national and international

Why is it important to PHE?

5. Threat to armed forces.

4. Increases PHE international profile

Development of a vaccine against CCHF virus

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6. Potential bioweapon

Why is it important to PHE?

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.

Development of a vaccine against CCHF virus

Lack of treatments against CCHFNo 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

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Alternative approach badly needed for a modern CCHF vaccine that can meet regulatory approval and is proven to be effective.

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

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Antigen sequence

N-terminal tPA for secretion& Nab induction

GFP for selection of recombinant viruses

Glycoprotein

L RTransferplasmid

L R

L RMVA genome

L R

MVA permissive cell

MVA

GFP+ plaquepurification

C-terminal V5 for in vitro antibody recognition

Development of a vaccine against CCHF virus

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Confirmation of antigen expression

MVA-G

P

posit

ive co

ntro

l

Anti-V5 antibody(expected size of GP-V5 fusion protein = 76.6kDa,

positive control protein = 62kDa)

MVA-1

974

CCHF+ SW

13

SW13

cells

MVA-G

P

Anti-CCHF rabbit polyclonal sera(similar post-translational cleavages in

MVA-GP to native protein)

Development of a vaccine against CCHF virus

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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.

Media

GP peptides

The vaccine induces cellular immunity…IFN- ELISPOT assay

Solid bars = 129Sv/Ev mice; hatched bars = A129 mice

Summed antigen responses Individual peptide pools

Development of a vaccine against CCHF virus

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…and humoral immunity.ELISA studies

The MVA-GP vaccine induced significant CCHF glycoprotein-specific antibodies.

Uninfe

cted

SW13

cells

CCHFv-inf

ecte

d SW

13 ce

lls

Western blot

Development of a vaccine against CCHF virus

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Day 0 7 14 21 28 35 42

Prime BoostCCHF

Challenge Analysis

Efficacy studies

100% protection from lethal challenge First demonstration of CCHF

vaccine efficacy

Development of a vaccine against CCHF virus

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RT-PCR for CCHFv gene expression (normalised to mouse HPRT gene expression).

Day 32 = 4 days post-challengeDay 42 = 14 days post-challenge (end of study)

Viral load was significantly lower in MVA-GP vaccinated mice than in control groups.

Viral loads

Blood LiverSpleen

Development of a vaccine against CCHF virus

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HistologyLiverSpleen

MVA-1974

MVA-GP

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).

H&E staining

Immunised A129 mice, 4 days post-challenge

Development of a vaccine against CCHF virus

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HistologyLiverSpleen

MVA-1974

MVA-GP

Immunostaining

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.

Development of a vaccine against CCHF virus

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Immunise mice with MVA-GP Isolate splenocytes (T-cells) and sera (antibody)from immunised mice

Adoptively transfer splenocytes into naïve mice

Passively transfer sera into naïve mice

Challenge with CCHF virus

Determine survival effects

Next steps

Development of a vaccine against CCHF virus

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

Market sizing

17 Development of a vaccine against CCHF virus

Summary

• 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).

18 Development of a vaccine against CCHF virus