Hepatitis C Vaccines

Michael HoughtonUniversity of Alberta

Incidence of HCV Infection

• WHO estimates 2-3 million new infections occurring globally p.a.

• USA CDC estimates ~ 20,000 new infections p.a.– Mostly in IDUs ( ~ 70% )

• Canadian PHA estimates 2,000-12,000 new infections p.a.

Adaptive HCV-specific immune responses correlate with recovery from acute HCV

infection

Cellular & Humoral immune responsesHCV-specific T cells & Neutralising

antibodies

Depletion of CD4+ T cells in convalescent chimpanzees leads to viral persistence following re-challenge

A Grakoui et al. Science 2003;302:659-662

Published by AAAS

Prophylactic HCV “T cell vaccine” in phase 2 efficacy testing

(A.Folgori et al. (Okairos & NIH))

• Prime/boost immunisation regimen using a chimpanzee adenovirus & modified vaccinia ankora expressing HCV genotype1b non-structural (NS) 3,4 & 5 genes – NS proteins encode large number of CD4+ and CD8+ epitopes– Both replication-defective viral vectors– Relies on multi-specific CD4+ & CD8+ T cell responses without any

neutralising antibody• Prototype vaccine tested in 5 chimpanzees

– Evidence for amelioration of acute hepatitis and acute viremia in vaccinees after experimental challenge with heterologous 1a virus

• But no significant difference in carrier rates• Efficacy data anticipated in 2016

– Earliest approval estimated ~ 2019

HuMAb HCV1 ( aa 412-423 ) protects chimpanzees from initial infection with HCV ( T.Morin et al 2012 )

A vaccine based on recombinant gpE1/gpE2 envelope glycoproteins

( M.Houghton Immunol Rev 2011 )

• Native heterodimer complex comprising both full-length envelope glycoproteins gpE1 (33KDa) + gpE2 (72KDa)

• Produced in CHO or HeLa cell-lines• gpE1/gpE2 retained in lumen of endoplasmic

reticulum via C-terminal transmembrane anchor regions

• Purified to homogeneity under native conditions

Oligomeric recombinant gpE1/gpE2 purified from CHO cells

(R.Ralston et al)

Prophylactic efficacy in non-human primate model

Adapted from Houghton, Immunological Review 2011

Viral challenge Group Total Acute infections Chronic infection (%)

gpE1/gpE2Unimmunized

HomologousHCV-1

1210

710

2(17)7(10)

P=0.003

HeterologousH77

gpE1/gpE2Unimmunized

1914

1914

3(16)8(57)

P=0.02

Total gpE1/gpE2Unimmunized

3124

2624

5(16)15(63)

P=<0.001

Phase I trial conducted by Chiron & NIH( S. Frey et al Vaccine 2010 ; R.Ray et al JID 2010 )

• The investigational E1E2/MF59 vaccine – Exhibits satisfactory safety and tolerability– Elicits anti-E1E2 (EIA) titers which are in the same

range as in vaccinated chimps– But protection in chimps did not always correlate with

elicited anti-E1E2 titers– Induces very strong lymphoproliferative responses to

E1E2

• 20ug E1E2 antigen dose administered on months 0,1 & 6 elicits optimal immunogenicity

Can antibodies elicited by a rec. gpE1/gpE2 vaccine neutralise viral infectivity ?

If so, is neutralisation strain-specific or broadly cross-neutralising ?

Vaccinees elicit broad cross-neutralizing antibodies( J.Law et al Plos One 2013 )

1 5 7

No

rma

lize

d N

eu

tral

iza

tion

(%

)

Binding

GAGs LDLR SR-B1 CD81

Post-binding

H+

Endosomal acidification, fusion, uncoating

Tight Junction

CLDN1

OCLN

HCV entry is a complex process involving several entry receptors and factors

Kong et. al., Science 2013Khan et al Nature 2014

Cross-neutralizing HCV monoclonal antibodies

Most isolated cross-neutralizing monoclonal antibodies are directed to gpE2 and can bind soluble gpE2

HVR1 TM

384 718 746

CD81CD81 CD81 CD81

396-424 433-447 523-540 611-616

Antibody AR3B ML 396-424 436-447 523-540 AP33 JB 412-423 HC84.26 SF

434-446 616

1:7 MP 523-540

Neutralising epitopes tend to cluster around CD81-binding regions Some Mabs are capable of binding to linear peptides (highlighted in red)

Two newly discovered antibodies have been shown to bind to the E1E2 complex (Mansun Law et al 2013 )

TM

192 383

gpE1

gpE2

HVR1 TM

384 718 746

CD81CD81 CD81 CD81

201-206

639-698

201 206YHVTND

657R

692 698DL

639R

Antibody AR4A: Y TND AR5A: Y TND

Antibody AR4A: R D L D AR5A: R R L D

658D

Can goats immunised with the clinical E1E2 vaccine elicit antibodies that compete with discrete cross-neutralising Mabs ?

( Jason Wong et al J Virol 2014)

Antisera from goats immunized with HCV1 E1E2 competes with cross-neutralizing Mabs recognizing diverse epitopes

Immunized goat antisera effectively competes for the binding of anti-E1 mAbs

(J.Wong et al JVI 2014 )

1:51:400 Wong et al., JVI 2014

*Results of Pre samples from five vaccinees were combined and the average is shown (V Pre)

Antisera from humans immunized with recombinant E1E2 competes for the binding of cross neutralizing anti-E2 and anti-E1E2 mAbs

Genotype effect?

Determining the composition of the vaccine cocktail (Collaboration with Joe Marcotrigiano lab)

E1E2 (G1a)-G714-G757

E2 (G2a)-G766-G773

E2 (G1a)-G786-G799

1a antigen 2a antigen

Genotype-specific neutralization N

eutr

aliz

atio

n (

%)

1a antigen 2a antigen

Antigen: E1E2 sE2 sE2 E1E2 sE2 sE2

Challenge virus: (1a) H77c/JFH1 (2a) J6/JFH1 Pre-

Add

IFA

Simmond P., JGV 2004

Simmonds et al., Hepatology 2005

HCV % difference

Genotypes 31-33

Subtypes 20-25

Designing the right cocktail for a global HCV vaccine

Serotype?

Future

• A 2nd-generation gpE1/gpE2 vaccine being developed for clinical testing in 2017– Contains modified gpE1/gpE2 antigen– Vaccine cocktail elicits neutralising antibodies

against all global HCV genotypes– New scaleable 2-step purification process from

CHO cell-lines– Significant improvements over prototype

gpE1/gpE2 vaccine

University of Alberta : John Law Jason Wong Mike Logan Darren Hockman Amir LandiChao Chen Janelle Johnson Wendy Magee

Funding support:Canada Excellence Research Chair (Houghton)Alberta Innovates-Health Solutions

Chiron Corp

• Qui-Lim Choo George Kuo

• Robert Ralston Sergio Abrignani Steve Coates Yui-lian Fong Kevin Crawford Mark Wininger Christine Dong

Acknowledgements

Joseph Marcotrigiano (Rutgers University)

Lorne Tyrrell (University of Alberta)

Judith Gottwein & Jens Bukh (University of Copenhagen)

Charles Rice (Rockefeller University)

Sharon Frey, Robert Belshe (Washington University, St Louis)

Tim Tellinghuisen (Scripps Florida)

Ralf Bartenschlager (Heidelberg University)

Arash Grakoui (Emory University)

Frank Chisari (Scripps)

Mansun Law (Scripps)

Arvind Patel (MRC)

Mats Persson (Karolinska Institutet)

Steven Foung (Stanford University)

National Institute of Allergy and Infectious DiseasesNovartis