Hepatitis C Vaccines
Michael Houghton
University 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 responses
HCV-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
Viral challenge Group
Total
Acute infections
Chronic infection (%)
Homologous gpE1/gpE2
HCV-1
Unimmunized
12
10
7
10
2(17)
7(10)
P=0.003
HeterologousgpE1/gpE2
H77
Unimmunized
19
14
19
14
3(16)
8(57)
P=0.02
Total
31
24
26
24
5(16)
15(63)
gpE1/gpE2
Unimmunized
P=<0.001
Adapted from Houghton, Immunological Review 2011
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 crossneutralising ?
Normalized Neutralization (%)
Vaccinees elicit broad cross-neutralizing antibodies
( J.Law et al Plos One 2013 )
1
5
7
HCV entry is a complex process involving several entry
receptors and factors
Binding
GAGs
LDLR
Post-binding
SR-B1
CD81
H+
CLDN1
OCLN
Tight Junction
Endosomal acidification,
fusion, uncoating
Cross-neutralizing HCV monoclonal antibodies
Kong et. al., Science 2013
Khan et al Nature 2014
Most isolated cross-neutralizing monoclonal antibodies
are directed to gpE2 and can bind soluble gpE2
396-424
433-447
523-540
611-616
384
718
TM
HVR1
CD81
Antibody
AR3B ML 396-424
AP33 JB 412-423
HC84.26
SF
1:7 MP
746
CD81
436-447
CD81
CD81
523-540
434-446
616
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 )
gpE1
201-206
192
383
TM
Antibody
AR4A:
AR5A:
201
206
YHVTND
Y TND
Y TND
gpE2
639-698
384
718
TM
HVR1
CD81
Antibody
AR4A:
AR5A:
746
CD81
CD81
CD81
639 657 658 692 698
R R D L
D
R D L
D
R R
L
D
Can goats immunised with the clinical E1E2 vaccine
elicit antibodies that compete with discrete crossneutralising Mabs ?
( Jason Wong et al J Virol 2014)
Antisera from goats immunized with HCV1 E1E2 competes with crossneutralizing Mabs recognizing diverse epitopes
Immunized goat antisera effectively competes for the
binding of anti-E1 mAbs
(J.Wong et al JVI 2014 )
1:400
1:5
Wong et al., JVI 2014
Antisera from humans immunized with recombinant E1E2
competes for the binding of cross neutralizing anti-E2 and antiE1E2 mAbs
*Results of Pre samples from five vaccinees were combined and the
average is shown (V Pre)
Determining the composition of the vaccine cocktail
(Collaboration with Joe Marcotrigiano lab)
Genotype effect?
E1E2 (G1a)
-G714
-G757
E2 (G1a)
-G786
-G799
E2 (G2a)
-G766
-G773
Genotype-specific neutralization
Neutralization (%)
Challenge virus:
100
(1a) H77c/JFH1
100
(2a) J6/JFH1
PreAdd
IFA
50
0
Antigen:
50
757
786
773
E1E2
sE2
sE2
1a antigen
2a antigen
0
757
E1E2
1a antigen
786
sE2
773
sE2
2a antigen
Designing the right cocktail for a global HCV vaccine
Serotype?
HCV
% difference
Genotypes
31-33
Subtypes
20-25
Simmonds et al., Hepatology 2005
Simmond P., JGV 2004
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 Landi
Chao 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 Diseases
Novartis