Pirbright and ISZLER. EuFMD Open Session 2018

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1 A universal test to quantitate protective antigen during production of foot-and-mouth disease vaccines Amin Asfor, Nathalie Howe, Santina Grazioli, Emiliano Brocchi and Toby Tuthill Pirbright and ISZLER EuFMD Open Session 2018

2 Foot-and-mouth disease virus (FMDV) Picornavirus family, related to poliovirus and rhinovirus Seven serotypes High levels of antigenic variation within serotypes Capsid protein VP4: internal and highly conserved Vaccine produced by chemical inactivation

3 The problem: vaccine integrity Intact antigen protective response 146S Dissociated subunits reduced immunogenicity altered antigenicity 12S

4 Existing approaches to measure vaccine integrity Virus particles separated by ultracentrifugation in sucrose gradients Use of 146S-specific antibodies epitope? specificity? Y Laborious, low throughput Virus serotype/strain specific

5 Existing approaches to measure vaccine integrity Virus particles separated by ultracentrifugation in sucrose gradients Use of 146S-specific antibodies Biologicals Oct;18(4): Quantification of intact 146S foot-and-mouth disease antigen for vaccine production by a double antibody sandwich ELISA using monoclonal antibodies. Van Maanen C 1, Terpstra C Laborious, low throughput

6 Fundamental research on picornavirus uncoating and membrane penetration Poliovirus Receptor Altered binding particle? Empty particle

7 RFU VP4 multimerises to form a sizeselective membrane pore PV VP4 Dye Release VP4 Liposomes only DE3 cells + liposomes Mellitin PV VP4 + liposomes 1µm mellitin + liposomes Controls Time (min) Time Hogle Lab, Harvard Medical School

8 How can the inside of a virus capsid contain targets for antibodies? The picornavirus capsid is a dynamic structure. Internal components that exit from the particle during cell entry are transiently exposed at the capsid surface under normal physiological conditions.

9 VP4 N terminus is very highly conserved among all FMDV serotypes Type O1 Manisa-AAT O1 M Type AA22/IRQ24/64 type C ACO Type Asia 1 ABF type SAT 1 ADI Type SAT 2 AGZ VP GAGQSSPATGSQNQSGNTGSIINNYYMQQYQNSMDTQLGDNATSGGSNEGSTDTTSTHTT -...I......I......I...N...I...N...I...N VP Type O1 Manisa-AAT O1 M NTQNNDWFSKLASSAFSGLFGALLADKKTEETTLLEDRILTTRNGHTTSTTQSSVGVTYG Type AA22/IRQ24/64... type C ACO F. Type Asia 1 ABF T...R...T...A... type SAT 1 ADI Q...V...SH.T...I... Type SAT 2 AGZ Q..I...H.T...F. Type O1 Manisa-AAT O1 M Type AA22/IRQ24/64 type C ACO Type Asia 1 ABF type SAT 1 ADI Type SAT 2 AGZ YATAEDFVSGPNTSGLETRVAQAERFFKTHLFDWVTSDPFGRCHLLELPTDHKGVYGSLT.S.Q..H...V...K...TPDKA..HLEK...H.V...ST...H...MA...P.QN..HM.KVV..HEP...G.V..V...A...T...K...TPNLA..H.YY...SE...M..SSDK..P...N...E...HK...TLEQK..TT.V...I..Q.V..D.DS.RP...Q...EK...TSDK...TLYV...K...I..K..

10 O D n m A broadly cross-reactive antibody. ELISA IF A s ia 1 A C O S A T 1 S A T 2 S A T 3 n e g a tiv e Microscopy by Stephen Berryman

11 O D recognizes an epitope in VP4 Western Blot KD - Asia 1 A C O SAT1 SAT2 SAT VP0 VP Peptide ELISA V P 4 N -1 5 V P 4 N -3 0 V P 4 N -4 5 V P 4 C -1 5 V P 4 C -4 5 V P 2 N -1 5 V P 2 N -3 0 V P 2 N -4 5 VP4 peptides p e p t id e s 1 u g /m l VP2 peptides

12 VP4 is exposed at the capsid surface but absent from dissociated subunits VP4 + VP4 - VP4 (VP4 epitope exposed) (VP4 lost upon dissociation)

13 O D (4 9 0 n m ) A universal ELISA for intact antigen Sample Heated (dissociates all antigen) Not-Heated (preserves all antigen) Capture with recombinant integrin Detect with VP4 specific antibody S S (heated) (not heated) A O IR A N S A T 1 S A T 2 S A T 3 C 1 0 u l o f v iru s ly s a te p e r w e ll-5 B 6 1 in in te g rin 1 in 7 5

14 O D ( n m ) O D n m A universal ELISA for intact antigen 1.5 A serotype 5 B S Concentration of capsid material v iru s d ilu tio n 5 B S M S VP4 antibody sample not heated M S VP4 antibody sample heated M170 existing 146S specific antibody 1.5 M S 5 B S O O 1 M a n is a A A

15 Summary Capsid dissociation is a major problem for vaccine antigen Capsid breathing allows internal conserved sequences (VP4) to form epitopes at the capsid surface Dissociated pentamers do not contain VP4 A VP4 specific monoclonal antibody can recognize all FMDV serotypes and has specificity for intact capsid A potential universal test for vaccine antigen Further work/test validation ongoing

16 Acknowledgements Pirbright Stephen Berryman Julian Seago Don King and WRLFMD EuFMD Keith Sumption BI Jose Coco-Martin Genomia Fund & BBSRC Impact Acceleration Award Continued development of a validated test

17 A universal test to quantitate protective antigen during production of foot-and-mouth disease vaccines Amin Asfor, Nathalie Howe, Santina Grazioli, Emiliano Brocchi and Toby Tuthill Pirbright and ISZLER EuFMD Open Session 2018