1.
New vaccine
technology: Hopes
and fears
Erwin van den Born, 27 October 2022
OS2022, Marseille

2.
Introduction
Erwin van den Born, PhD
Sr R&D Project Leader
MSD Animal Health, Boxmeer, The Netherlands
Responsible for the development of vaccines against viral diseases in pigs, since 2010
Experience with ASFV, CSFV, FMDV, PPV, PRV and PRRSV
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3.
COVID-19
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NL
US
AUS
Rapid response by the scientific community,
pharmaceutical industry, and regulatory agencies
First approval of a mRNA vaccines for use in humans
Fear and scepticism among some

4.
What do new vaccine technologies bring?
Hopes
Better and longer protection
Enhance mucosal immunity
Better safety – fewer side effects
Easier to administer
More stable
Cheaper
Quicker response to emergencies
DIVA – differentiation of infected and vaccinated animals (‘marker’)
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Fears
GMO vaccines
Integration in the genome (DNA vaccines and DNA viruses e.g.
adenovirus vectors)
Recombination with circulating strains and reversion to virulence (live
attenuated vaccines)
Persistent replication of vectors or live attenuated strains and DNA
vaccines (DNA up to 2 years)
Vaccine contamination with adventitious agents
Long-term negative effect on vaccinated individuals (e.g. auto-
immunity)
The presence of antibiotic resistant genes

5.
Vaccine technologies
Vaccine types
Nucleic acid (mRNA or DNA)
Subunit (incl. virus-like particles)
Live attenuated
Inactivated
Peptide
Vectors (see list)
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Vectors (replication compotent and replication
defective):
Replication deficient adenovirus (e.g. human Ad5 or Ad24)
Replication competent adenovirus
Vaccinia (MVA)
Alphavirus vector, such as VEEV (‘self replicating RNA’)
Vesicular stomatitis virus (VSV)
Canarypox
Measles virus (MV)
Herpesvirus

6.
Why are new vaccine technologies needed?
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Vaccine technology generations:
First generation
• The classical inactivated (‘killed’)
• Modified-live vaccines (MLV)
Second generation
• Subunit
• Conjugated/recombinant antigens
• Synthetic proteins
Third generation
• Nucleic acid (DNA and RNA) vaccines
• Viral-vector platforms
• Live or inactivated chimeric vaccines
Why are 2nd and 3rd generation vaccines being
developed:
Successes with 1st generation vaccines, but also limitations:
• Efficacy of inactivated vaccines can be suboptimal
• Safety concerns around MLV vaccines
• Slow response to new outbreaks.

7.
Virus Genes Genome
size (kb)
Virion size
(nm)
Proteins
in virion
ASFV 170 180 200 50
Coronavirus 10 30 120 5
PRRSV 10 15 60 8
PPV 2 5 22 2
PCV2 5 2 17 1
Complexity of porcine
viruses
Bacteria
The challenge with 2nd and 3rd gen vaccines –
Which protein provides protection?

8.
Successful application of 2nd and 3rd gen vaccine technologies
–examples 1
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Example subunit vaccine
FMDV P1-2A-3C cassette in baculovirus expression
system yields immunogenic virus-like particles
Strain Vaccine Dose
VN titers
(log10)
Protection
Asia1/Shamir
VLP 5 µg 2.1 5/5
classic 5 µg 2.1 4/5
SAT2/SAU/6/00
VLP 10 µg 2.4 5/5
classic 10 µg 2.5 5/5
Example nucleic acid vaccine
SARS-CoV2 Spike gene in mRNA vector (or viral vector).
Mimicking spike presentation in CoV infection.
Joubert et al., 2021, BJOG

9.
• SAME platform is used for ALL vaccines
• Attenuated Venezuelan equine encephalitis virus (strain TC-83)
• Broad, balanced immune response
• On market in US
• Farm-specific vaccine (e.g. strains selected by veterinarian)
• Can target diseases not addressed by conventional vaccines
• Multivalent formulations
• No need to culture pathogen
• No or very limited anti-vector immunity
Swine influenza
H3N2
challenge
experiment:
Successful application of 2nd and 3rd gen vaccine technologies
–examples 2

10.
Existing immunity and booster capabilities
Booster capabilities can be limited for:
- Modified live vaccines
- Vector vaccines (e.g. Adenovirus vectors)
Potentially powerful combinations:
- 2 vaccine technologies: e.g. DNA vaccine and vector
- 2 different routes of administration

11.
Characteristics of a succesful vaccine
Important for veterinary vaccines are the costs of goods
- Rough sales price for different species:
- Dog: € 10
- Pig: € 1
- Chick: € 0.01
- If I’m correct, the cost price of a mRNA vaccine was around € 10.- pre-covid, now around € 2-3 🡪 only an option for companion animals?!
Production considerations:
- Live attenuated and vectors are relatively cheap to produce
- Stability:
- Loss of gene insert: from pre-master seed to production seed is easily 5 passages
- Loss of attenuating mutation(s) during passaging/production
- Advantage of platform vaccines, such as nucleic acid vaccine: 1 production process for all targets is a great advantage for manufacturer. If
chemically synthesized, less risk of adventitious agents
- Cost of containment: mostly BSL2 facilities; sometimes BSL3

12.
Adjuvant technologies: beyond the classic adjuvants
such as oil-in-water or water-in-oil types
- Molecular adjuvants.
- Usually plasmid-encoded signaling molecules such as cytokines and
chemokines, but also pattern recognition receptor (PRR) ligands.
Molecular adjuvants are co-delivered with the antigen.
- Safety concern: use of co-stimulatory molecules may lead to unintended
adverse effects such as generalized immune suppression, chronic
inflammation or autoimmunity.
- Delivery of nucleic acid vaccines: Delivery of mRNA to cytoplasm and DNA
to nucleus. Efficacy of mRNA vaccines can be enhanced by complexing
agents such as lipid- and polymer-based nanoparticles.
- VLPs loaded with antigens/peptides: next slide
Schoenmaker et al., 2021, International Journal of Pharmaceutics

13.
Virus-like particles as vehicles for heterologous antigens
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Kumar et al., 2020 BioPharm International

14.
Vaccine application technologies
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Poultry: spray vaccination of 1-day old chickens Swine: needle-free intradermal vaccination with the IDAL
Why different application routes:
- Ease of use and human safety (e.g. needleless)
- Animal welfare
- Speed and cost
- Better immunity: e.g. a mucosal response benefits from oral or nasal delivery
- Etc

15.
Vaccine application technology in fishery
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Skala
www.thefishsite.com

16.
Regulatory landscape
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A trend towards platform technologies (EMA)
• ‘Plug and play’ (vectors, mRNA/DNA, baculovirus expression)
• Multi-strain dossier
Nucleic acid vaccines
• DNA vaccines: The FDA and WHO advise integration studies
as part of the preclinical safety program
• What is the master seed of a mRNA or DNA vaccine?
Combining technologies
• 2 different vaccine technologies or other combinations could
make vaccine production and the registration process
challenging.
Stages of vaccine development and approval stages
European Medicines Agency (EMA)

17.
Conclusions
Vaccine technologies evolve to develop safe, efficacious, stable,
and cost-effective vaccines for existing and emerging infectious
pathogens.
Need for awareness of the risks and limitations of certain
technologies
In veterinary health, numerous novel technologies have already
been employed. The human health field is generally more
cautious and hesitant.
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18.
Thank you