1. A PRIME-BOOST VACCINATION STRATEGY IN CATTLE TO PREVENT SEROTYPE O FMDV INFECTION USING A “SINGLE-CYCLE” ALPHAVIRUS VECTOR AND EMPTY CAPSID PARTICLES
Maria Gullberg1, Louise Lohse1, Anette Bøtner1, Gerald M. McInerney2, Alison Burman3, Terry Jackson3, Charlotta Polacek1 and Graham J. Belsham1
1DTU National Veterinary Institute, Technical University of Denmark, Lindholm, Kalvehave, Denmark
2Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Stockholm, Sweden.
3The Pirbright Institute, Pirbright, Woking, Surrey, U.K

2. Summary ●Single cycle alphavirus vector (rSFV-FMDV) expresses FMDV empty capsid particles ● Single vaccination of cattle with rSFV-FMDV induces anti-FMDV antibodies but not protection ● Vaccination with rSFV-FMDV primes an anti-FMDV immune response ● Vaccination with rSFV-FMDV followed by empty capsids induces protection ● No viremia observed post-challenge in cattle

3. Why recombinant FMDV vaccines?
Challenge:
Current FMDV vaccines are not optimal
Chemically inactivated virus has to be grown under high containment
Short duration of immunity
Aim:
Develop an improved, safe, vaccine based on expression of self-assembling empty capsid particles within cells
- No serotype cross protection
- Short vaccine protection time
- Vaccine stability
- Airborne
- Some animal species high shedders, poor indicator animals
2 "New FMDV vaccine approach"
(aims: ... etc. as in this slide) 3

4. FMDV particle formation
3B1-3
Lab
VP A Lb
VP2 VP3 VP1 2B 2C 3A 3C D
FMDV
VP0
(Empty capsid particle proteins)
VP VP VP1
Encapsidation of RNA
(Virus particle proteins)
VP VP VP VP1
Empty capsid particle
Virus particle
Belsham & Bøtner, 2015

5. rSFV-FMDV design
FMDV cDNA
SFV vector

6. SFV split helper system
Vaccine
Expression of
foreign protein
Smerdou and Liljeström, 1999 6

7. Expression of FMDV capsid proteins by rSFV-FMDV vectors
Antigen ELISA WB
Abs 450nm
Sucrose
gradient
Gullberg et al., 2016

8. Single inoculation of cattle with rSFV-FMDV vectors and FMDV challenge
Ab ELISA
Temperature
Viremia
Outcome
Control
FMD
rSFV-P1-2A
FMD
rSFV-P1-2A-mIRES3C
FMD

9. Anti-FMDV antibody titres (ELISA)
Group
Animal
PVD 14
PVD 21
PVD 27
PVD 30
1 Control C1 - 20 1 C2
2 rSFV-P1-2A C3
320 2 C4 C5 5
>640
3 rSFV-P1-2A-mIRES-3C C6 10 3 C7 C8
Low titre anti-FMDV response induced by rSFV-FMDV alone.
Much stronger anti-FMDV response post challenge (on PVD 21) in rSFV-FMDV inoculated animals
Gullberg et al., 2016

10. Prime-boost strategy Use of: 1) rSFV-P1-2A-mIRES-3C
2) Purified ”empty capsid” (EC) particles (expressed from vaccinia virus vectors, Porta et al., 2013).
Plan (3 groups)
1) Control (no inoculation)
2) Inoculate with rSFV-P1-2A-mIRES-3C (PVD 0), then boost with ECs (on PVD 14)
3) Inoculate with ECs (PVD 0), then boost with rSFV-P1-2A-mIRES-3C (on PVD 14)
Challenge with FMDV on PVD 28

11. Protection against FMDV challenge
FMDV RNA
Temperature
Control
FMD
rSFV + ECs
No disease
ECs + rSFV
FMD
Gullberg et al., 2016

12. Anti-FMDV responses in cattle
Ab ELISA
VNT titre
VNT titres
Pre-boost
Control
Pre-challenge
rSFV + EC
EC + rSFV
Post-challenge
Gullberg et al., 2016

13. Conclusions rSFV-FMDV vectors can express FMDV empty capsids in cells
Single inoculation with rSFV-FMDVs induces low titre anti-FMDV responses BUT primes antibody induction
Prime-boost strategy using rSFV-FMDV vector followed by ECs generates strong anti-FMDV response that blocks FMDV dissemination in cattle following challenge
The prime-boost strategy using rSFV-FMDV vectors and ECs has properties at least as good as current vaccine and can be made outside of high containment
Duration of immunity, minimum dose required etc. … to be determined